Method and device for voltage detection and charging of electric battery

[0001] 1. Field of the Invention

[0002] The present invention is related to battery chargers in general, and more specifically to a method and device for rated voltage detection and charging of an electric battery.

[0003] 2. Description of the Prior Art

[0004] Conventional methods for battery charging are cumbersome, time-consuming, and error-prone. Current battery chargers capable of charging batteries of different voltages, require users to manually select a rated (or nominal) voltage of the battery to be charged in order for the battery to be properly charged, and not damaged by the charging process. If a user selects a wrong battery rated voltage, the battery may not be properly charged, and the battery and/or the charger may be permanently damaged.

[0005] Manual selection of the battery voltage, however, is subject to the user actually knowing the proper battery voltage rating, and correctly selecting the voltage rating on the battery charger itself. Because rechargeable batteries can have different voltage ratings, even among batteries with the same form factor, the voltage rating of a specific battery may not be obvious to a user. Furthermore, physically selecting a voltage rating on a battery charger may be hampered by environmental conditions, such as darkness or moisture, or deterioration of the controls on the battery charger itself.

[0006] With this in mind, a need exists to develop a charger that automatically detects the voltage of an electric battery that advances the art.

[0007] The present invention provides a novel device and method for rated voltage detection and charging of electric batteries, such as lead-acid batteries commonly used in cars, trucks and other motor vehicles.

[0008] According to one aspect of the present invention, a method is provided for rated voltage detection and charging of an electric battery. The rated voltage detection and charging method of the present invention comprises the following steps. First, the rated voltage detection and charging device is connected to a power source. Then, a terminal voltage of the electric battery is measured. The electric battery has a rated voltage, which could be either a first rated voltage or a second rated voltage, wherein the first rated voltage is less than said second rated voltage. Next, the measured terminal voltage is compared to a number of threshold voltages between a minimum threshold DC voltage V_MIN and a maximum threshold DC voltage V_MAX. In the following step, a condition of the battery is determined based on a comparison of the terminal voltage to the threshold voltages. The condition of the battery is ready to charge or fault. If the determined condition of the battery is ready to charge, it is determined that the rated voltage of the battery is the second rated voltage. However, if the determined condition of the battery is neither ready to charge nor fault, then a pre-charge process is conducted. Following the pre-charge process, the rated voltage of the electric battery is determined based on a response to the pre-charge process. Next, the electric battery is charged according to the rated voltage determined in the preceding step.

[0009] According to another aspect of the invention, a device is provided for detecting a rated voltage of an electric battery and subsequent charging thereof. The rated voltage detection and charging device of the present invention comprises a battery charging unit and a voltage detection unit operatively connected to the battery charging unit. The voltage detection unit includes a microprocessor in communication with the battery charging unit and configured to determine a condition of the electric battery based on a comparison of a terminal voltage of the battery to a number of threshold voltages between a minimum threshold DC voltage V_MIN and a maximum threshold DC voltage V_MAX and a rated voltage of the electric battery based on a response to a pre-charge process. The condition of the electric battery is ready to charge or fault. The rated voltage of the electric battery is either a first rated voltage or a second rated voltage, wherein the first rated voltage is less than the second rated voltage. The pre-charge process is conducted if the determined condition of the electric battery is neither ready to charge nor fault. The voltage detection unit is further provided to activate the battery charging unit for charging the battery according to the determined rated voltage.

[0021] The preferred embodiments of the present invention will now be described with the reference to accompanying drawings.

[0022] FIG. 1 of the drawings depicts a device, generally denoted by reference numeral 10, for rated voltage detection and charging of electric batteries, such as lead-acid batteries commonly used in cars, trucks and other motor vehicles, according to a first exemplary embodiment of the present invention.

[0023] The detection and charging device 10 comprises a battery charging unit 12, a voltage detection unit 14 operatively (electrically) connected the battery charging unit 12, positive and negative battery terminal clamps (electrical connectors) 16 and 17, respectively, connected to the battery charging unit 12 through positive and negative battery booster cables 18 and 19, respectively, and an electrical connector (AC input) 20 provided for selectively connecting the battery charging unit 12 of the device 10 to an AC (alternating current) power source, such as a conventional 120 volt circuit. The pair of the clamps 16 and 17 is provided for selectively conducting charging current from the battery charging unit to an electric battery 22. Conventionally, the positive clamp 16 is provided to be connected to a positive battery terminal 23, while the negative clamp 17 is provided to be connected to a negative battery terminal 24 of the electric battery 22. As further illustrated in FIG. 1, the battery charging unit 12 and the voltage detection unit 14 are housed within a casing 11.

[0024] The voltage detection unit 14 is provided to accomplish the following functions: 1) determine a condition of the battery 22 (which could be “ready-to-charge” or “fault”) based on a comparison of a terminal voltage V_T of the electric battery 22 to a number of threshold voltages between a minimum threshold DC voltage V_MIN and a maximum threshold DC voltage V_MAX, conduct a pre-charge process if the determined condition of the battery 22 is neither “ready-to-charge” nor “fault”, determine a rated (or nominal) voltage of the battery 22 based on a response to the pre-charge process, and activate the battery charging unit 12 for charging the battery 22 according to the determined rated voltage. The rated voltage of the battery 22 is one of a first rated voltage and a second rated voltage.

[0025] Those skilled in the art would understand that the rated (or nominal) voltage is one of the most important characteristics of an electric battery. Conventionally, in the lead-acid batteries, the rated voltage is a multiple of the 2 V individual cell voltage. It is well known in the art that the rated voltage is a voltage at which an electric battery is designed to operate, or, in other terms, the rated voltage is a voltage at which an electric battery capacity is rated. Typical rated voltage for motor vehicle electrical system batteries is 12 V for passenger cars and 24 V for commercial vehicles. In the past, the rated voltage for motor vehicle electrical system batteries used to be 6 V. Thus, many classic and/or collectors cars still use the electric batteries rated at 6 V.

[0026] The voltage detection/charging device 10, according to the present invention, is provided to determine a condition of the battery 22 based on a comparison of the terminal voltage V_T of the electric battery 22 to a number of threshold voltages between a minimum threshold DC voltage V_MIN and a maximum threshold DC voltage V_MAX, conduct a pre-charge process if a certain condition of the battery 22 is met, determine a rated voltage of the battery 22 based on a response to the pre-charge process, and activate the battery charging unit 12 for charging the battery 22 according to the determined rated voltage. According to the preferred embodiment of the present invention, the voltage detection and charging device 10 is provided to detect the rated voltage and charge the electric batteries with at least two different rated voltages, such as, for example, 6 V and 12 V or 12 V and 24 V.

[0027] FIGS. 2, 3A and 3B illustrate a device 10₁ for rated voltage detection and charging of electric batteries according to a first exemplary embodiment of the present invention. The detection and charging device (or detection/charging device) 10₁ is provided for automatic voltage detection for batteries rated 6 or 12 volt. As illustrated in FIGS. 2-4, the detection/charging device 10₁ comprises a casing 11₁ housing a battery charging unit 12₁ and a voltage detection unit 14₁ operatively (electrically) connected the battery charging unit 12₁, and includes a control panel 15₁ provided with a number of control lights and push buttons. The voltage detection unit 14₁ of the detection/charging device 10₁ can be configured to automatically control some or all of the operation thereof. Various charging characteristics may be specified. As one example, different charging rates may be selected depending on a size of the battery 22 to be tested or charged.

[0028] The control panel 15₁ of the detection/charging device 10₁ includes a power on/off push button 26, a charge rate select (“Select 2/4/6 AMP”) push button 28₁, a Stand-by (or “Power”) LED light 31₁, a “Charged” LED light 32₁, a “Charging” LED light 34₁ and a “Wrong Connection” (or “Bad Connection”) LED light 36₁. The control panel 15₁ of the detection/charging device 10₁ further includes 2 AMP, 4 AMP and 6 AMP LED lights 38₁, 40₁ and 42₁, respectively. Also, the control panel 15₁ of the detection/charging device 10₁ includes a “Bad Battery” LED light 44₁, and “6 Volt” and “12 Volt” LED lights 46₁ and 48₁, respectively.

[0029] The detection/charging device 10₁ has three charge rate settings for 12 Volt batteries: 2 A (Trickle Charge), 4 A (Medium Charge) and 6 A (Quick Charge) and one charge rate setting for 6 Volt batteries: 2 A (Trickle Charge), specified through the charge rate select push button 28₁ depending on a size of the battery 22 to be tested and/or charged:

[0030] 2 Amp (Trickle Charge) (for both 6 and 12V batteries): smaller batteries, as in lawn mowers, snowmobiles, motorcycles, etc.;

[0031] 4 Amp (Medium Charge) (for 12V batteries only): mid-sized batteries, as in small cars; and

[0032] 6 Amp (Quick Charge) (for 12V batteries only): large batteries, as in midsize to large automobiles and SUV's.

[0033] It will be appreciated that the specific charge rate setting is selected by repeatedly pressing the “Select 2/4/6 AMP” push button 28₁ until the corresponding 2 AMP, 4 AMP or 6 AMP LED light, 38₁, 40₁ or 42₁, is illuminated.

[0034] FIGS. 3A and 3B illustrate an electric circuit diagram of the voltage detection/charging device 10₁. As noted above, the detection/charging device 10₁ is configured to automatically control some or all of the operation of the battery charging unit 12₁. Alternatively, different charging rates, such as low, medium and high, may be manually selected.

[0035] The voltage detection unit 14₁ of the detection/charging device 10₁ is provided to monitor the battery status (i.e. configured to monitor various characteristics of the battery 22), such as the battery voltage and battery current. The voltage detection unit 14₁ may monitor characteristics of the battery in real time, and report the condition and/or characteristics of the battery 22 on the control panel 15₁. By continuously monitoring one or more characteristics of the battery 22, the detection/charging device 10₁ may also control for various charging errors, such as short circuit, overload, overheat, reverse connection, etc. The battery charging unit 12₁ provided to charge the battery 22 produces a full waved rectified voltage. The battery charging unit 12₁ includes the AC input 20, a bridge type rectifier 21 configured to convert the AC voltage to full wave DC voltage, and a transformer 30. The transformer 30 is selectively connected to the terminals 23, 24 of the battery 22 through the positive and negative battery booster cables 18 and 19. In the case of standard U.S. household current the frequency of the voltage is 60 Hz.

[0036] The voltage detection unit 14₁ includes an electronic control unit (ECU) in the form of a microprocessor (MCU) 50, shown in FIG. 3B. The microprocessor 50 is configured to control proper operation and fault detection of the detection/charging device 10₁ and to monitor a plurality of characteristics of the battery 22, including a terminal voltage V_T of the electric battery 22 and a current supplied by the battery 22. Those skilled in the art would understand that the term “terminal voltage” is conventionally known in the art as a voltage measured at battery terminals. The terminal voltage of a battery can be measured as an indication of state of charge of the battery. Moreover, the microprocessor (MCU) 50 further controls charging current, charging voltage, charging time, LED light status, etc.

[0037] The voltage detection unit 14₁ also includes an integrated circuit (IC) 54 provided to control a MOSFET 55 and the output of the transformer 30, an optocoupler 56, a relay 58 and a 95° C. thermal protector 60.

[0038] The voltage detection/charging device 10₁ is provided to determine a condition of the battery 22 based on a comparison of the terminal voltage V_T of the electric battery 22 to a number of threshold voltages between a minimum threshold DC voltage V_MIN and a maximum threshold DC voltage V_MAX, conduct a pre-charge process if a certain condition of the battery 22 is met, determine a rated voltage of the battery 22 based on a response to the pre-charge process, and activate the battery charging unit 12₁ for charging the battery 22 according to the determined rated voltage. According to the first exemplary embodiment of the present invention, the voltage detection/charging device 10₁ is provided to detect the rated voltage and charge the electric batteries with two different rated voltages: 6V and 12V.

[0039] FIG. 4 is a flowchart illustrates a method 100 for rated voltage detection and charging of the electric battery in accordance with the first exemplary embodiment of the present invention, which can be implemented by the voltage detection/charging device 10₁. The first exemplary embodiment of the present invention relates to the device for voltage detection and charging of the electric batteries having two different rated voltages: 6 V (a first rated voltage) and 12 V (a second rated voltage).

[0040] In a first step 102, the voltage detection/charging device 10₁ is connected the AC power source, such as a conventional 120 volt, 60 Hz circuit, through the electrical connector (AC input) 20. Moreover, in the first step 102, the voltage detection/charging device 10₁ is connected to the electric battery 22 via the battery terminal clamps 16, 17 of the battery booster cables 18, 19.

[0041] After the initial step 102, the voltage detection/charging device 10₁ goes on to a step 104 of detecting the rated voltage of the battery 22 by, first, measuring the terminal voltage V_T of the electric battery 22, then comparing the terminal DC voltage to a number of threshold voltages between a minimum threshold DC voltage V_MIN and a maximum threshold DC voltage V_MAX. Obviously, the maximum threshold DC voltage V_MAX is larger than the minimum threshold DC voltage V_MIN (i.e., V_MAX>V_MIN). Preferably, according to the first exemplary embodiment of the present invention, the minimum threshold DC voltage V_MIN is 0.5 VDC (volts of direct current), while the maximum threshold DC voltage V_MAX is 15 VDC. The threshold voltages, besides the minimum threshold DC voltage V_MIN and the maximum threshold DC voltage V_MAX, are: a first threshold DC voltage V₁ (1.5 VDC according to the first exemplary embodiment of the present invention), a second threshold DC voltage V₂ (6.9 VDC according to the first exemplary embodiment of the present invention), and a third threshold DC voltage V₃ (13.8 VDC according to the first exemplary embodiment of the present invention).

[0042] Next, a condition of the electric battery 22 is determined by the microprocessor 50 of the voltage detection unit 14₁ based on a comparison of the terminal voltage V_T to the threshold voltages. The condition of the electric battery 22 determined by the voltage detection unit 14₁ is one of “12V and ready-to-charge” 106 and “fault”. In turn, the “fault” condition of the battery 22 may be “bad connection” 108 and “bad battery” (110a and 110b, or [110]). The term “bad battery” means that the electric battery cannot function as intended (for intended purposes). According to the first exemplary embodiment of the present invention, the “bad connection” condition 108 is determined by the voltage detection unit 14₁ when the terminal voltage V_T of the battery 22 is less than the minimum threshold DC voltage V_MIN (i.e., when V_T<V_MIN) (the step 104a). In other words, according to the first exemplary embodiment of the present invention, the “bad connection” condition 108 is determined by the voltage detection unit 14₁ when the terminal voltage V_T of the battery 22 is less than 0.5 VDC (i.e., when V_T<0.5 VDC). If the “bad connection” condition 108 is determined, the “Bad Connection” LED light 36₁ is illuminated.

[0043] The “bad battery” condition [110] is determined when the terminal voltage V_T of the electric battery 22 is equal or more than the minimum threshold DC voltage V_MIN and equal or less than the first threshold DC voltage V₁ (i.e., when V_MIN≦V_T≦V₁) (step 104b, condition 110a), or when the terminal voltage of the battery is more than the maximum threshold DC voltage V_MAX (i.e., when V_T>V_MAX) (step 104c, condition 110b). In other words, according to the first exemplary embodiment of the present invention, the “bad battery” condition [110] is determined by the voltage detection unit 14₁ when the terminal voltage V_T of the battery 22 is between equal or more than 0.5 VDC and equal or less than 1.5 VDC (i.e., when 0.5 VDC≦V_T≦1.5 VDC) (step 104b, condition 110a), or when the terminal voltage of the battery is more than 15 VDC (i.e., when V_T>15 VDC) (step 104c, condition 110b). If the “bad battery” condition [110] is determined, the “Bad Battery” LED light 44₁ is illuminated.

[0044] The “12V and ready-to-charge” condition 106 is determined by the microprocessor 50 when the terminal voltage V_T of the electric battery 22 is equal or more than the second threshold DC voltage V₂ and equal or less than the third threshold DC voltage V₃ (i.e., when V₂≦V_T≦V₃) (step 104d). In other words, according to the first exemplary embodiment of the present invention, the “12V and ready-to-charge” condition is determined by the voltage detection unit 14₁ when the terminal voltage V_T of the battery 22 is equal or more than 6.9 VDC and equal or less than 13.8 VDC (i.e., when 6.9 VDC≦V_T≦13.8 VDC, or when the terminal voltage V_T is in the range 6.9 VDC-13.8 VDC) (step 104d). Moreover, when the microprocessor 50 of the voltage detection unit 14₁ determines that a battery condition is “12V and ready-to-charge” (i.e., when the terminal voltage V_T is in the range 6.9 VDC-13.8 VDC), then the microprocessor 50 determines that the electric battery 22 is rated at 12 V. Consequently, the “12 V” LED lamp 48₁ is illuminated on the control panel 15₁ of the voltage detection/charging device 10₁, and charging of the electric battery 22 is initiated at the step 112 by pressing the power push button 26 by the user and, consequently, by the battery charging unit 12₁ at a charging DC voltage equal to 14.6 VDC according to the first exemplary embodiment of the present invention.

[0045] However, if the condition of the electric battery 22 determined by the microprocessor 50 is neither “ready-to-charge” nor “fault”, both the “6 Volt” and “12 Volt” LED lights 46₁ and 48₁ will flash, thus indicating that a pre-charge process needs to be conducted. In response, the user presses the power button 26 (the step 114) to initiate the pre-charge process. In other words, the step of conducting the pre-charge process is initiated when the terminal voltage V_T of the electric battery 22 is more than the first threshold DC voltage V₁ and less than the second threshold DC voltage V₂ (the step 104e). According to the first exemplary embodiment of the present invention, the step of conducting a pre-charge process is initiated when the terminal voltage V_T of the electric battery 22 is more than 1.6 VDC and less than 6.8 (i.e., when 1.5 VDC<V_T<6.9 VDC, or when the terminal voltage V_T is in the range 1.6 VDC-6.8 VDC).

[0046] During the step 116 of the pre-charge process, the electric battery 22 is pre-charged for a first predetermined period of time by a pre-charge DC current I_PRE at a pre-charge DC voltage V_PRE, which is less than V_MAX and higher than V_MIN. As noted above, according to the first exemplary embodiment of the present invention, the pre-charge current I_PRE is 6 A. Specifically, the voltage detection/charging device 10₁ of the first exemplary embodiment of the present invention includes the three LED lights 38₁, 40₁ and 42₁ provided on the control panel 15₁ of the voltage detection/charging device 10₁ for displaying three different charge rate settings: 2 A, 4 A and 6 A, respectively. The 2 A charge rate setting is provided for smaller batteries rated 6 V or 12 V, such as batteries for lawn mowers, snowmobiles, motorcycles, etc. The 4 A charge rate setting is provided for mid-sized batteries rated 12 V, such as in small cars. The 6 A charge rate setting is provided for mid-sized batteries rated 12 V, such as in medium and full-sized cars, SUVs, trucks, etc. The user manually selects the charge rate setting prior to the pre-charge process by pressing the charge rate select (“Select 2/4/6 AMP”) button 28₁ depending on the size of the electric battery 22 and the desired rate of charging. In the exemplary embodiment of FIG. 4, the user selects the 6 AMP charge rate for quick charge with the pre-charge DC current I_PRE of 6 A. The pre-charge process is initiated by pressing the power button 26 on the control panel 15₁ of the voltage detection/charging device 10₁ depending on a size of the battery 22 to be tested and/or charged and the desired rate of charging. According to the first exemplary embodiment of the present invention, the pre-charge DC current I_PRE is 6 A and the pre-charge voltage V_PRE is 8 VDC, while the first predetermined period of time is 4 minutes.

[0047] Following the step 116 of pre-charging the battery at the pre-charge DC voltage V_PRE for the first predetermined period of time by the pre-charge DC current I_PRE, the pre-charge process ends with the step 118 of stopping the pre-charge process for a second predetermined period of time in order to allow the battery 22 to settle. According to the first exemplary embodiment of the present invention, the second predetermined period of time is 1 minute.

[0048] Next, a rated voltage of the electric battery 22 is determined (the step 120) by the microprocessor 50 of the voltage detection unit 14₁ based on a response to the pre-charge process, which includes the steps 114, 116 and 118. As noted above, the rated voltage of the electric battery 22 according to the first exemplary embodiment of the present invention could be 6 V (the first rated voltage) or 12 V (the second rated voltage). In turn, the step 120 of determining the rated voltage of the electric battery 22, executed following the pre-charge process (steps 114, 116 and 118), includes the following steps. First, the terminal voltage V_T of the electric battery 22 is measured by the voltage detection unit 14₁ following the pre-charge process. Then, the voltage detection unit 14₁ determines that the electric battery 22 has the first rated voltage (6 V) (the step 122) if the terminal voltage V_T of the electric battery 22 after the pre-charge process is less than the second threshold DC voltage V₂ (the step 121). In other words, if V_T<6.9 VDC (the step 121), then it is determined that the electric battery 22 is rated 6 V (the step 122). Consequently, the “6 V” LED lamp 46₁ is illuminated on the control panel 15₁ of the voltage detection/charging device 10₁.

[0049] Similarly, if the terminal voltage V_T of the electric battery 22 after the pre-charge process is equal or more than the second threshold DC voltage V₂ (the step 123), then the voltage detection unit 14₁ determines that the electric battery 22 has the second rated voltage (12 V) (the step 124). In other words, if V_T>6.8 VDC (the step 123), then it is determined that the electric battery 22 is rated 12 V (the step 124). Consequently, the “12 V” LED lamp 48₁ is illuminated on the control panel 15₁ of the voltage detection/charging device 10₁.

[0050] Subsequently, the electric battery 22 is charged by the battery charging unit 12₁ according to the determined voltage rating. More specifically, the electric battery 22 is charged at a first charging DC voltage V_CH1 by a first charging current I_CH1 (the step 126) until fully charged (the step 128) if the battery 22 is determined to have the first rated voltage (6 V) (in the step 122), and at a second charging DC voltage V_CH2 by a second charging current I_CH2 (the step 130) until fully charged (the step 132) if the battery 22 is determined to have the second rated voltage (12 V) (in the step 124). According to the first exemplary embodiment of the present invention, the first charging DC voltage V_CH1 is 7.3 VDC, the first charging current I_CH1 is 0.8 A, the second charging DC voltage V_CH2 is 14.6 VDC and the second charging current I_CH2 is 0.8 A.

[0051] When the battery 22 is fully charged at the step 128 or 132 (depending on the determined battery voltage rating), the full charge process ends with the step 134 or 136 of stopping the charging process for a third predetermined period of time in order to allow the battery 22 to settle. According to the first exemplary embodiment of the present invention, the third predetermined period of time is 2 minutes.

[0052] After the third predetermined period of time expires, the condition of the electric battery 22 is again determined by the microprocessor 50 based on a comparison of the terminal voltage V_T to the first rated voltage (6 V) (if the battery 22 is determined (in the step 122) to have the first rated voltage) in the step 138 or to the second rated voltage (12 V) (if the battery 22 is determined (in the step 124) to have the second rated voltage) in the step 140. The “bad battery” condition is determined by the voltage detection unit 14₁ when the terminal voltage V_T of the battery 22 is less than the first rated voltage (6 V) (i.e., when V_T<6 VDC) if the battery 22 is rated 6 V (the step 142). Similarly, the “bad battery” condition is determined by the voltage detection unit 14₁ when the terminal voltage V_T of the battery 22 is less than the second rated voltage (12 V) (i.e., when V_T<12 VDC) if the battery 22 is rated 12 V (the step 144).

[0053] FIGS. 5 and 6 illustrate a device 10₂ for rated voltage detection and charging of electric batteries according to a second exemplary embodiment of the present invention. Components, which are unchanged from the previous exemplary embodiment of the present invention, are labeled with the same reference characters. Components, which function in the same way as in the first exemplary embodiment of the present invention depicted in FIGS. 1-4 are designated by the same reference numerals to which the subscript 2 or 100 has been added, sometimes without being described in detail since similarities between the corresponding parts in the two embodiments will be readily perceived by the reader.

[0054] The detection and charging device (or detection/charging device) 10₂ is provided for automatic voltage detection for batteries rated 12 or 24 volt. As illustrated in FIG. 5, the detection/charging device 10₂ comprises a casing 11₂ housing a battery charging unit 12₂ and a voltage detection unit 14₂ operatively (electrically) connected the battery charging unit 12₂, and includes a control panel 15₂ provided with a number of control lights and push buttons. The voltage detection unit 14₂ of the detection/charging device 10₂ can be configured to automatically control some or all of the operation thereof. Various charging characteristics may be specified. As one example, different charging rates may be selected depending on a size of the battery 22 to be tested or charged.

[0055] The control panel 15₂ of the detection/charging device 10₂ includes a power on/off push button 26, a charge rate select (“Select 2/6/10 AMP”) push button 28₂, a Stand-by (or power) LED light 31₂, a “Charging” LED light 34₂ and a “Wrong Connection” (or “Bad Connection”) LED light 36₂. The control panel 15₂ of the detection/charging device 10₂ further includes a set of LED light indicating a battery charge level, specifically: a “Low Charge” LED light 32₂₀, a “50% Charge” LED light 32₂₁, a “75% Charge” LED light 32₂₂ and a “Full Charge” LED light 32₂₃. The control panel 15₂ of the detection/charging device 10₂ also includes 2 AMP, 6 AMP and 10 AMP LED lights 38₂, 40₂ and 42₂, respectively. Also, the control panel 15₂ of the detection/charging device 10₂ includes a “Bad Battery” LED light 44₂, and “12 Volt” and “24 Volt” LED lights 46₂ and 48₂, respectively.

[0056] The detection/charging device 10₂ has three charge rate settings for 12 and 24 Volt batteries: 2 A (Trickle Charge), 6 A (Medium Charge) and 6 10 (Quick Charge), specified through the charge rate select push button 28₂ depending on a size of the battery 22 to be tested and/or charged:

[0057] 2 Amp (Trickle Charge) (for both 12V and 24V batteries): smaller batteries, as in lawn mowers, snowmobiles, motorcycles, etc.;

[0058] 6 Amp (Medium Charge) (for both 12V and 24V batteries): mid-sized batteries, as in small cars; and

[0059] 10 Amp (Quick Charge) (for 12V batteries only): large batteries, as in midsize to large automobiles and SUV's.

[0060] FIG. 6 illustrates an electric circuit diagram of the voltage detection/charging device 10₂. As noted above, the detection/charging device 10₂ is configured to automatically control some or all of the operation of the battery charging unit 12₂. Alternatively, different charging rates, such as low, medium and high, may be manually selected.

[0061] The voltage detection unit 14₂ of the detection/charging device 10₂ is provided to monitor the battery status (i.e. configured to monitor various characteristics of the battery 22), such as the battery voltage and battery current. The voltage detection unit 14₂ may monitor characteristics of the battery in real time, and report the condition and/or characteristics of the battery 22 on the control panel 15₂. By continuously monitoring one or more characteristics of the battery 22, the detection/charging device 10₂ may also control for various charging errors, such as short circuit, overload, overheat, reverse connection, etc. The battery charging unit 12₂ provided to charge the battery 22 produces a full waved rectified voltage. The battery charging unit 12₂ includes the AC input 20, a bridge type rectifier 21 configured to convert the AC voltage to full wave DC voltage, a main transformer 30a and an auxiliary transformer 30b, and MOSFETs 55. The main transformer 30a is selectively connected to the terminals 23, 24 of the battery 22 through the positive and negative battery booster cables 18 and 19. In the case of standard U.S. household current the frequency of the voltage is 60 Hz. The auxiliary transformer 30b drives the MOSFETs 55 and controls the operation of the main transformer 30a.

[0062] The voltage detection unit 14₂ includes an electronic control unit (ECU) in the form of a microprocessor (MCU) 50, shown in FIG. 6. The microprocessor 50 is configured to control proper operation and fault detection of the detection/charging device 10₂ and to monitor a plurality of characteristics of the battery 22, including a terminal voltage V_T of the electric battery 22 and a current supplied by the battery 22. Those skilled in the art would understand that the term “terminal voltage” is conventionally known in the art as a voltage measured at battery terminals. The terminal voltage of a battery can be measured as an indication of state of charge of the battery. Moreover, the microprocessor (MCU) 50 further controls charging current, charging voltage, charging time, LED light status, etc.

[0063] The voltage detection unit 14₂ also includes an integrated circuit (IC) 54 provided to control the MOSFETs 55 and the output of the auxiliary transformer 30b, an optocoupler 56, and relays 58.

[0064] The voltage detection/charging device 10₂ is provided to determine a condition of the battery 22 based on a comparison of the terminal voltage V_T of the electric battery 22 to a number of threshold voltages between a minimum threshold DC voltage V_MIN and a maximum threshold DC voltage V_MAX, conduct a pre-charge process if a certain condition of the battery 22 is met, determine a rated voltage of the battery 22 based on a response to the pre-charge process, and activate the battery charging unit 12₂ for charging the battery 22 according to the determined rated voltage. According to the second exemplary embodiment of the present invention, the voltage detection/charging device 10₂ is provided to detect the rated voltage and charge the electric batteries with two different rated voltages: 12V and 24V.

[0065] FIG. 7 is a flowchart illustrates a method 200 for rated voltage detection and charging of the electric battery in accordance with the second exemplary embodiment of the present invention, which can be implemented by the voltage detection/charging device 10₂. The second exemplary embodiment of the present invention relates to the device for voltage detection and charging of the electric batteries having two different rated voltages: 12 V (a first rated voltage) and 24 V (a second rated voltage).

[0066] In a first step 202, the voltage detection/charging device 10₂ is connected the AC power source, such as a conventional 120 volt, 60 Hz circuit, through the electrical connector (AC input) 20. Moreover, in the first step 202, the voltage detection/charging device 10₂ is connected to the electric battery 22 via the battery terminal clamps 16, 17 of the battery booster cables 18, 19.

[0067] After the initial step 202, the voltage detection/charging device 10₂ goes on to a step 204 of detecting the rated voltage of the battery 22 by, first, measuring the terminal voltage V_T of the electric battery 22, then comparing the terminal DC voltage to a number of threshold voltages between a minimum threshold DC voltage V_MIN and a maximum threshold DC voltage V_MAX. Obviously, the maximum threshold DC voltage V_MAX is larger than the minimum threshold DC voltage V_MIN (i.e., V_MAX>V_MIN). Preferably, according to the second exemplary embodiment of the present invention, the minimum threshold DC voltage V_MIN is 0.5 VDC (volts of direct current), while the maximum threshold DC voltage V_MAX is 30 VDC. The threshold voltages, besides the minimum threshold DC voltage V_MIN and the maximum threshold DC voltage V_MAX, are: a first threshold DC voltage V₁ (1.5 VDC according to the second exemplary embodiment of the present invention), a second threshold DC voltage V₂ (13.8 VDC according to the second exemplary embodiment of the present invention), and a third threshold DC voltage V₃ (27.6 VDC according to the second exemplary embodiment of the present invention).

[0068] Next, a condition of the electric battery 22 is determined by the microprocessor 50 of the voltage detection unit 14₂ based on a comparison of the terminal voltage V_T to the threshold voltages. The condition of the electric battery 22 determined by the voltage detection unit 14₂ is one of “24V and ready-to-charge” 206 and “fault”. In turn, the “fault” condition of the battery 22 may be “bad connection” 208 and “bad battery” (210a and 210b, or [210]). The term “bad battery” means that the electric battery cannot function as intended (for intended purposes). According to the second exemplary embodiment of the present invention, the “bad connection” condition 208 is determined by the voltage detection unit 14₂ when the terminal voltage V_T of the battery 22 is less than the minimum threshold DC voltage V_MIN (i.e., when V_T<V_MIN) (the step 204a). In other words, according to the first exemplary embodiment of the present invention, the “bad connection” condition 208 is determined by the voltage detection unit 14₂ when the terminal voltage V_T of the battery 22 is less than 0.5 VDC (i.e., when V_T<0.5 VDC). If the “bad connection” condition 208 is determined, the “Bad Connection” LED light 36₂ is illuminated.

[0069] The “bad battery” condition [210] is determined when the terminal voltage V_T of the electric battery 22 is equal or more than the minimum threshold DC voltage V_MIN and equal or less than the first threshold DC voltage V₁ (i.e., when V_MIN≦V_T≦V₁) (step 204b, condition 210a), or when the terminal voltage of the battery is more than the maximum threshold DC voltage V_MAX (i.e., when V_T>V_MAX) (step 204c, condition 210b). In other words, according to the first exemplary embodiment of the present invention, the “bad battery” condition [210] is determined by the voltage detection unit 14₁ when the terminal voltage V_T of the battery 22 is between equal or more than 0.5 VDC and equal or less than 1.5 VDC (i.e., when 0.5 VDC≦V_T≦1.5 VDC) (step 204b, condition 210a), or when the terminal voltage of the battery is more than 30 VDC (i.e., when V_T>30 VDC) (step 204c, condition 210b). If the “bad battery” condition [210] is determined, the “Bad Battery” LED light 44₂ is illuminated.

[0070] The “24V and ready-to-charge” condition 206 is determined by the microprocessor 50 when the terminal voltage V_T of the electric battery 22 is equal or more than the second threshold DC voltage V₂ and equal or less than the third threshold DC voltage V₃ (i.e., when V₂≦V_T≦V₃) (step 204d). In other words, according to the second exemplary embodiment of the present invention, the “24V and ready-to-charge” condition (206) is determined by the voltage detection unit 14₂ when the terminal voltage V_T of the battery 22 is equal or more than 13.8 VDC and equal or less than 27.6 VDC (i.e., when 13.8 VDC≦V_T≦27.6 VDC, or when the terminal voltage V_T is in the range 13.8 VDC-27.6 VDC) (step 204d). Moreover, when the microprocessor 50 of the voltage detection unit 14₂ determines that a battery condition is “24V and ready-to-charge” (i.e., when the terminal voltage V_T is in the range 13.8 VDC-27.6 VDC), then the microprocessor 50 determines that the electric battery 22 is rated at 24 V. Consequently, the “24 V” LED lamp 48₂ is illuminated on the control panel 15₂ of the voltage detection/charging device 10₂, and charging of the electric battery 22 is initiated at the step 212 by pressing the power push button 26 by the user and, consequently, by the battery charging unit 12₂ at a charging DC voltage equal to 28.8 VDC according to the second exemplary embodiment of the present invention.

[0071] However, if the condition of the electric battery 22 determined by the microprocessor 50 is neither “ready-to-charge” nor “fault”, both the “12 Volt” and “24 Volt” LED lights 46₂ and 48₂ will flash, thus indicating that a pre-charge process needs to be conducted. In response, the user presses the power button 26 (the step 214) to initiate the pre-charge process. In other words, the step of conducting a pre-charge process is initiated when the terminal voltage V_T of the electric battery 22 is more than the first threshold DC voltage V₁ and less than the second threshold DC voltage V₂ (the step 204e). According to the second exemplary embodiment of the present invention, the step of conducting a pre-charge process is initiated when the terminal voltage V_T of the electric battery 22 is more than 1.6 VDC and less than 13.7 (i.e., when 1.5 VDC<V_T<13.8 VDC, or when the terminal voltage V_T is in the range 1.6 VDC-13.7 VDC).

[0072] During the step 216 of the pre-charge process, the electric battery 22 is pre-charged for a first predetermined period of time by a pre-charge DC current I_PRE at a pre-charge DC voltage V_PRE, which is less than V_MAX and higher than V_MIN. As noted above, according to the first exemplary embodiment of the present invention, the pre-charge current I_PRE is one of 2 A, 6 A and 10 A. Also, the voltage detection/charging device 10₂ of the second exemplary embodiment of the present invention is provided with 2 AMP, 6 AMP and 10 AMP LED lights 38₂, 40₂ and 42₂, respectively, provided on the control panel 15₂ of the voltage detection/charging device 10₂, for displaying three different charge rate settings: 2 A, 6 A and 10 A, respectively. The 2 A charge rate setting is provided for smaller batteries rated 12 V or 24 V, such as batteries for lawn mowers, snowmobiles, motorcycles, etc. The 6 A charge rate setting is provided for mid-sized batteries also rated 12 V or 24 V, such as in small cars. The 10 A charge rate setting is provided for mid-sized batteries rated 12 V, such as in medium and full-sized cars, SUVs, trucks, etc.

[0073] The user manually selects the charge rate setting prior to the pre-charge process by pressing the charge rate select (“Select 2/6/10 AMP”) button 28₂ depending on the size of the electric battery 22 and the desired rate of charging. In the second exemplary embodiment of the present invention of FIG. 7, the user selects the 10 AMP charge rate for quick charge with the pre-charge DC current I_PRE of 10 A. The pre-charge process is initiated by pressing the power button 26 on the control panel 15₂ of the voltage detection/charging device 10₂ depending on a size of the battery 22 to be tested and/or charged and the desired rate of charging. According to the second exemplary embodiment of the present invention, the pre-charge DC current I_PRE is 10 A and the pre-charge voltage V_PRE is 16 VDC, while the first predetermined period of time is 4 minutes.

[0074] Following the step 216 of pre-charging the battery at the pre-charge DC voltage V_PRE for the first predetermined period of time by the pre-charge DC current I_PRE, the pre-charge process ends with the step 218 of stopping the pre-charge process for a second predetermined period of time in order to allow the battery 22 to settle. According to the second exemplary embodiment of the present invention, the second predetermined period of time is 1 minute.

[0075] Next, a rated voltage of the electric battery 22 is determined (the step 220) by the microprocessor 50 of the voltage detection unit 14₂ based on a response to the pre-charge process, which includes the steps 214, 216 and 218. As noted above, the rated voltage of the electric battery 22 according to the second exemplary embodiment of the present invention could be 12 V (the first rated voltage) or 24 V (the second rated voltage). In turn, the step 220 of determining the rated voltage of the electric battery 22, executed following the pre-charge process (steps 214, 216 and 218), includes the following steps. First, the terminal voltage V_T of the electric battery 22 is measured by the voltage detection unit 14₂ following the pre-charge process. Then, the voltage detection unit 14₂ determines that the electric battery 22 has the first rated voltage (12 V) (the step 222) if the terminal voltage V_T of the electric battery 22 after the pre-charge process is less than the second threshold DC voltage V₂ (the step 221). In other words, if V_T<13.9 VDC (the step 221), then it is determined that the electric battery 22 is rated 12 V (the step 222). Consequently, the “12 V” LED lamp 46₂ is illuminated on the control panel 15₂ of the voltage detection/charging device 10₂.

[0076] Similarly, if the terminal voltage V_T of the electric battery 22 after the pre-charge process is equal or more than the second threshold DC voltage V₂ (the step 223), then the voltage detection unit 14₂ determines that the electric battery 22 has the second rated voltage (24 V) (the step 224). In other words, if V_T>13.8 VDC (the step 223), then it is determined that the electric battery 22 is rated 24 V (the step 224). Consequently, the “24 V” LED lamp 48₂ is illuminated on the control panel 15₂ of the voltage detection/charging device 10₂.

[0077] Subsequently, the electric battery 22 is charged by the battery charging unit 12₂ according to the determined voltage rating. More specifically, the electric battery 22 is charged at a first charging DC voltage V_CH1 by a first charging current I_CH1 (the step 226) until fully charged (the step 228) if the battery 22 is determined to have the first rated voltage (12 V) (in the step 222), and at a second charging DC voltage V_CH2 by a second charging current I_CH2 (the step 230) until fully charged (the step 232) if the battery 22 is determined to have the second rated voltage (24 V) (in the step 224). According to the second exemplary embodiment of the present invention, the first charging DC voltage V_CH1 is 14.6 VDC, the first charging current I_CH1 is 0.8 A, the second charging DC voltage V_CH2 is 28.8 VDC and the second charging current I_CH2 is 0.8 A.

[0078] When the battery 22 is fully charged at the step 228 or 232 (depending on the determined battery voltage rating), the full charge process ends with the step 234 or 236 of stopping the charging process for a third predetermined period of time in order to allow the battery 22 to settle. According to the first exemplary embodiment of the present invention, the third predetermined period of time is 2 minutes.

[0079] After the third predetermined period of time expires, the condition of the electric battery 22 is again determined by the microprocessor 50 based on a comparison of the terminal voltage V_T to the first rated voltage (12 V) (if the battery 22 is determined (in the step 222) to have the first rated voltage) in the step 238 or to the second rated voltage (24 V) (if the battery 22 is determined (in the step 224) to have the second rated voltage) in the step 240. The “bad battery” condition is determined by the voltage detection unit 14₂ when the terminal voltage V_T of the battery 22 is less than the first rated voltage (12 V) (i.e., when V_T<12 VDC) if the battery 22 is rated 12 V (the step 242). Similarly, the “bad battery” condition is determined by the voltage detection unit 14₂ when the terminal voltage V_T of the battery 22 is less than the second rated voltage (24 V) (i.e., when V_T<24 VDC) if the battery 22 is rated 24 V (the step 244).

[0080] FIGS. 8 and 9 illustrate a device 10₃ for rated voltage detection and charging of electric batteries according to a third exemplary embodiment of the present invention. Components, which are unchanged from the previous exemplary embodiments of the present invention, are labeled with the same reference characters. Components, which function in the same way as in the first exemplary embodiment of the present invention depicted in FIGS. 1-4 are designated by the same reference numerals to which the subscript 3 or 200 has been added, sometimes without being described in detail since similarities between the corresponding parts in the two embodiments will be readily perceived by the reader.

[0081] The detection and charging device (or detection/charging device) 10₃ is provided for automatic voltage detection for batteries rated 6 or 12 volt. As illustrated in FIGS. 8 and 9, the detection/charging device 10₃ comprises a casing 11₃ housing a battery charging unit 12₃ and a voltage detection unit 14₃ operatively (electrically) connected the battery charging unit 12₃, and includes a control panel 15₃ provided with a number of control lights. The voltage detection unit 14₃ of the detection/charging device 10₃ can be configured to automatically control some or all of the operation thereof. Various charging characteristics may be specified.

[0082] The control panel 15₃ of the detection/charging device 10₃ includes a “Power” LED light 31₃, a “Full Charge” LED light 32₃, a “Fault” LED light 44₃, and 6 Volt and 12 Volt LED lights 46₃ and 48₃, respectively. The detection/charging device 10₃ has only one charge rate setting for 6 and 12 Volt batteries: 2 A (Trickle Charge).

[0083] FIG. 9 illustrates an electric circuit diagram of the voltage detection/charging device 10₃. As noted above, the detection/charging device 10₃ is configured to automatically control some or all of the operation of the battery charging unit 12₃. The voltage detection unit 14₃ of the detection/charging device 10₃ is provided to monitor the battery status (i.e. configured to monitor various characteristics of the battery 22), such as the battery voltage and battery current. The voltage detection unit 14₃ may monitor characteristics of the battery in real time, and report the condition and/or characteristics of the battery 22 on the control panel 15₃. By continuously monitoring one or more characteristics of the battery 22, the detection/charging device 10₃ may also control for various charging errors, such as short circuit, overload, overheat, reverse connection, etc. The battery charging unit 12₃ provided to charge the battery 22 produces a full waved rectified voltage. The battery charging unit 12₃ includes the AC input 20, a bridge type rectifier 21 configured to convert the AC voltage to full wave DC voltage, and a transformer 230. The transformer 230 is selectively connected to the terminals 23, 24 of the battery 22 through the positive and negative battery booster cables 18 and 19. In the case of standard U.S. household current the frequency of the voltage is 60 Hz.

[0084] The voltage detection unit 14₃ includes an electronic control unit (ECU) in the form of a microprocessor (MCU) 50. The microprocessor 50 is configured to control proper operation and fault detection of the detection/charging device 10₃ and to monitor a plurality of characteristics of the battery 22, including a terminal voltage V_T of the electric battery 22 and a current supplied by the battery 22. Those skilled in the art would understand that the term “terminal voltage” is conventionally known in the art as a voltage measured at battery terminals. The terminal voltage of a battery can be measured as an indication of state of charge of the battery. Moreover, the microprocessor (MCU) 50 further controls charging current, charging voltage, charging time, LED light status, etc. The voltage detection unit 14₃ also includes an integrated circuit (IC) 54 provided to control a MOSFET 55 and the output of the transformer 30, an optocoupler 56, a relay 58 and a 95° C. thermal protector 60.

[0085] The voltage detection/charging device 10₃ is provided to determine a condition of the battery 22 based on a comparison of the terminal voltage V_T of the electric battery 22 to a number of threshold voltages between a minimum threshold DC voltage V_MIN and a maximum threshold DC voltage V_MAX, conduct a pre-charge process if a certain condition of the battery 22 is met, determine a rated voltage of the battery 22 based on a response to the pre-charge process, and activate the battery charging unit 12₃ for charging the battery 22 according to the determined rated voltage. According to the third exemplary embodiment of the present invention, the voltage detection/charging device 10₃ is provided to detect the rated voltage and charge the electric batteries with two different rated voltages: 6V and 12V.

[0086] FIG. 10 is a flowchart illustrates a method 300 for rated voltage detection and charging of the electric battery in accordance with the third exemplary embodiment of the present invention, which can be implemented by the voltage detection/charging device 10₃. The third exemplary embodiment of the present invention relates to the device for voltage detection and charging of the electric batteries having two different rated voltages: 6 V (a first rated voltage) and 12 V (a second rated voltage).

[0087] In a first step 302, the voltage detection/charging device 10₃ is connected the AC power source, such as a conventional 120 volt, 60 Hz circuit, through the electrical connector (AC input) 20. Moreover, in the first step 302, the voltage detection/charging device 10₃ is connected to the electric battery 22 via the battery terminal clamps 16, 17 of the battery booster cables 18, 19.

[0088] After the initial step 302, the voltage detection/charging device 10₃ goes on to a step 304 of detecting the rated voltage of the battery 22 by, first, measuring the terminal voltage V_T of the electric battery 22, then comparing the terminal DC voltage to a number of threshold voltages between a minimum threshold DC voltage V_MIN and a maximum threshold DC voltage V_MAX. Obviously, the maximum threshold DC voltage V_MAX is larger than the minimum threshold DC voltage V_MIN (i.e., V_MAX>V_MIN). Preferably, according to the third exemplary embodiment of the present invention, the minimum threshold DC voltage V_MIN is 0.5 VDC (volts of direct current), while the maximum threshold DC voltage V_MAX is 15 VDC. The threshold voltages, besides the minimum threshold DC voltage V_MIN and the maximum threshold DC voltage V_MAX, are: a first threshold DC voltage V₁ (1.5 VDC according to the first exemplary embodiment of the present invention), a second threshold DC voltage V₂ (6.9 VDC according to the first exemplary embodiment of the present invention), and a third threshold DC voltage V₃ (13.8 VDC according to the first exemplary embodiment of the present invention).

[0089] Next, a condition of the electric battery 22 is determined by the microprocessor 50 of the voltage detection unit 14₃ based on a comparison of the terminal voltage V_T to the threshold voltages. The condition of the electric battery 22 determined by the voltage detection unit 14₃ is one of “12V and ready-to-charge” 306 and “Fault” (310a, 310b and 310c, or [310]). The term “Fault” condition means that the connection between the voltage detection/charging device 10₃ and the electric battery 22 is bad, or that the electric battery 22 cannot function as intended (for intended purposes). According to the third exemplary embodiment of the present invention, the “Fault” condition [310] is determined by the voltage detection unit 14₃ when the terminal voltage V_T of the battery 22 is less than the minimum threshold DC voltage V_MIN (i.e., when V_T<V_MIN) (the step 304a). In other words, according to the third exemplary embodiment of the present invention, the “Fault” condition [310] is determined when the terminal voltage V_T of the battery 22 is less than 0.5 VDC (i.e., when V_T<0.5 VDC).

[0090] The “Fault” condition [310] is also determined when the terminal voltage V_T of the electric battery 22 is equal or more than the minimum threshold DC voltage V_MIN and equal or less than the first threshold DC voltage V₁ (i.e., when V_MIN≦V_T≦V₁) (step 304b, condition 310a), or when the terminal voltage of the battery 22 is more than the maximum threshold DC voltage V_MAX (i.e., when V_T>V_MAX) (step 304c, condition 310b). In other words, according to the third exemplary embodiment of the present invention, the “Fault” condition [310] is determined by the voltage detection unit 14₃ when the terminal voltage V_T of the battery 22 is less than 0.5 VDC (i.e., when V_T<0.5 VDC) (step 304a, condition 310c), when the terminal voltage V_T of the battery 22 is between equal or more than 0.5 VDC and equal or less than 1.5 VDC (i.e., when 0.5 VDC≦V_T≦1.5 VDC) (step 304b, condition 310a), or when the terminal voltage of the battery is more than 15 VDC (i.e., when V_T>15 VDC) (step 304c, condition 310b). If the “Fault” condition [310] is determined, the “Fault” LED light 44₃ is illuminated.

[0091] The “12V and ready-to-charge” condition 306 is determined by the microprocessor 50 when the terminal voltage V_T of the electric battery 22 is equal or more than the second threshold DC voltage V₂ and equal or less than the third threshold DC voltage V₃ (i.e., when V₂≦V_T≦V₃) (step 304d). In other words, according to the third exemplary embodiment of the present invention, the “12V and ready-to-charge” condition is determined by the voltage detection unit 14₃ when the terminal voltage V_T of the battery 22 is equal or more than 6.9 VDC and equal or less than 13.8 VDC (i.e., when 6.9 VDC≦V_T≦13.8 VDC, or when the terminal voltage V_T is in the range 6.9 VDC-13.8 VDC) (step 304d). Moreover, when the microprocessor 50 of the voltage detection unit 14₃ determines that a battery condition is “12V and ready-to-charge” (i.e., when the terminal voltage V_T is in the range 6.9 VDC-13.8 VDC), then the microprocessor 50 determines that the electric battery 22 is rated at 12 V. Consequently, the “12 V” LED lamp 48₃ is illuminated on the control panel 15₃ of the voltage detection/charging device 10₃, and charging of the electric battery 22 is initiated at the step 312 by the battery charging unit 12₃ at a charging DC voltage equal to 14.6 VDC according to the third exemplary embodiment of the present invention.

[0092] However, if the condition of the electric battery 22 determined by the microprocessor 50 is neither “12V nor ready-to-charge” nor “fault”, both the “6 Volt” and “12 Volt” LED lights 46₃ and 48₃ will flash, thus indicating that a pre-charge process needs to be conducted. Subsequently, the microprocessor 50 of the voltage detection unit 14₃ instructs the battery charging unit 12₃ to conduct a pre-charge process, and the battery charging unit 12₃ will initiate the pre-charge process. In other words, the step of conducting the pre-charge process is initiated when the terminal voltage V_T of the electric battery 22 is more than the first threshold DC voltage V₁ and less than the second threshold DC voltage V₂ (the step 304e). According to the third exemplary embodiment of the present invention, the step of conducting a pre-charge process is initiated when the terminal voltage V_T of the electric battery 22 is more than 1.6 VDC and less than 6.8 (i.e., when 1.5 VDC<V_T<6.9 VDC, or when the terminal voltage V_T is in the range 1.6 VDC-6.8 VDC).

[0093] During the step 316 of the pre-charge process, the electric battery 22 is pre-charged for a first predetermined period of time by a pre-charge DC current I_PRE at a pre-charge DC voltage V_PRE, which is less than V_MAX and higher than V_MIN. As noted above, according to the third exemplary embodiment of the present invention, the pre-charge current I_PRE is 2 A for trickle charging of the electric battery 22. Further according to the third exemplary embodiment of the present invention, the pre-charge voltage V_PRE is 8 VDC, while the first predetermined period of time is 4 minutes.

[0094] Following the step 316 of pre-charging the battery at the pre-charge DC voltage V_PRE for the first predetermined period of time by the pre-charge DC current I_PRE, the pre-charge process ends with the step 318 of stopping the pre-charge process for a second predetermined period of time in order to allow the battery 22 to settle. According to the third exemplary embodiment of the present invention, the second predetermined period of time is 1 minute.

[0095] Next, a rated voltage of the electric battery 22 is determined (the step 320) by the microprocessor 50 of the voltage detection unit 14₃ based on a response to the pre-charge process, which includes the steps 314, 316 and 318. As noted above, the rated voltage of the electric battery 22 according to the third exemplary embodiment of the present invention could be 6 V (the first rated voltage) or 12 V (the second rated voltage). In turn, the step 320 of determining the rated voltage of the electric battery 22, executed following the pre-charge process (steps 314, 316 and 318), includes the following steps. First, the terminal voltage V_T of the electric battery 22 is measured by the voltage detection unit 14₃ following the pre-charge process. Then, the voltage detection unit 14₃ determines that the electric battery 22 has the first rated voltage (6 V) (the step 322) if the terminal voltage V_T of the electric battery 22 after the pre-charge process is less than the second threshold DC voltage V₂ (the step 321). In other words, if V_T<6.9 VDC (the step 321), then it is determined that the electric battery 22 is rated 6 V (the step 322). Consequently, the “6 V” LED lamp 46₃ is illuminated on the control panel 15₃ of the voltage detection/charging device 10₃.

[0096] Similarly, if the terminal voltage V_T of the electric battery 22 after the pre-charge process is equal or more than the second threshold DC voltage V₂ (the step 323), then the voltage detection unit 14₃ determines that the electric battery 22 has the second rated voltage (12 V) (the step 324). In other words, if V_T>6.8 VDC (the step 323), then it is determined that the electric battery 22 is rated 12 V (the step 324). Consequently, the “12 V” LED lamp 48₃ is illuminated on the control panel 15₃ of the voltage detection/charging device 10₃.

[0097] Subsequently, the electric battery 22 is charged by the battery charging unit 12₃ according to the determined voltage rating. More specifically, the electric battery 22 is charged at a first charging DC voltage V_CH1 by a first charging current I_CH1 (the step 326) until fully charged (the step 328) if the battery 22 is determined to have the first rated voltage (6 V) (in the step 322), and at a second charging DC voltage V_CH2 by a second charging current I_CH2 (the step 330) until fully charged (the step 332) if the battery 22 is determined to have the second rated voltage (12 V) (in the step 324). According to the third exemplary embodiment of the present invention, the first charging DC voltage V_CH1 is 7.3 VDC, the first charging current I_CH1 is 0.8 A, the second charging DC voltage V_CH2 is 14.6 VDC and the second charging current I_CH2 is 0.8 A.

[0098] When the battery 22 is fully charged at the step 328 or 332 (depending on the determined battery voltage rating), the full charge process ends with the step 334 or 336 of stopping the charging process for a third predetermined period of time in order to allow the battery 22 to settle. According to the third exemplary embodiment of the present invention, the third predetermined period of time is 2 minutes.

[0099] After the third predetermined period of time expires, the condition of the electric battery 22 is again determined by the microprocessor 50 based on a comparison of the terminal voltage V_T to the first rated voltage (6 V) (if the battery 22 is determined (in the step 322) to have the first rated voltage) in the step 338 or to the second rated voltage (12 V) (if the battery 22 is determined (in the step 324) to have the second rated voltage) in the step 340. The “bad battery” condition is determined by the voltage detection unit 14₃ when the terminal voltage V_T of the battery 22 is less than the first rated voltage (6 V) (i.e., when V_T<6 VDC) if the battery 22 is rated 6 V (the step 342). Similarly, the “bad battery” condition is determined by the voltage detection unit 14₃ when the terminal voltage V_T of the battery 22 is less than the second rated voltage (12 V) (i.e., when V_T<12 VDC) if the battery 22 is rated 12 V (the step 344).

[0100] The foregoing description of the preferred embodiments of the present invention has been presented for the purpose of illustration in accordance with the provisions of the Patent Statutes. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. The embodiments disclosed hereinabove were chosen in order to best illustrate the principles of the present invention and its practical application to thereby enable those of ordinary skill in the art to best utilize the invention in various embodiments and with various modifications as suited to the particular use contemplated, as long as the principles described herein are followed. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains. Thus, changes can be made in the above-described invention without departing from the intent and scope thereof. It is also intended that the scope of the present invention be defined by the claims appended thereto.