Chester Simpson
National Semiconductor, Santa Clara, CA
The battery charger lead acid in Figure, works with any gel or wet cell, lead, 12V battery. The charger includes adequate temperature compensation for output voltage of the charger, and a detector which indicates when the battery is fully charged.
The best battery chargers for lead-acid battery is a voltage source current limited power sources on the battery until it reaches the point of tension. The shipper must provide enough current to keep the battery voltage to this value. To 12V, the lead-acid batteries, a voltage magnitude of approximately 13.8 V at 25 ° C is typical. However, the optimal set point voltage call depends on the temperature. Battery manufacturers recommend a CT scan of 22 mV /°C, so the charger voltage setting of the TC tracks the battery.
You can determine the state of charge of a lead-acid battery voltage and load current. When charging the battery with a voltage source set to 13.8 V, the charge current gradually decreases to a very low value when the battery is fully charged. The design in Figure includes a detection circuit that turns on full charge LED when the current falls below this threshold.
This design features a 12V charger, 0.5A wall transformer and a voltage regulator LM2941CT, IC2. The wall transformer provides regulated DC voltage of IC2, the circuit used to charge the battery and keep tension on 13.8V. R3, R4, and D3 through D12 set the output voltage regulator. R4 should be adjusted for an output voltage of 13.8 V with the battery disconnected. An important feature of any wall transformer load regulation is poor. For example, the transformer of Figure set to 12V when charged to 0.5V,but approximately 17 to 18 V without load. The design takes advantage of this feature, because it means that IC2 not require heat sink.
D12 D3 through negative-TC set out required to match the voltage of the battery terminal. Measurements of some 1N4148 diodes at 1 mA show a TC of 2.2 mV / °C, so 10V of these diodes in series to provide the necessary 22 mV / °C. R5 and D13 indicate the presence of power or when the battery is connected to the output and provide the minimum load required for IC2. Stabilizes C1 for IC2.
A battery has a voltage of about 10 to 12V. If you connect a battery charger output, IC2 fully active (saturated fatty acids) the pass transistor. Under this condition, all power leads IC2 possible to try to force the battery voltage to the reference point 13.8. Thus, while the battery is below 13.8 V acts, IC2 as a power source. The maxim that the wall transformer may be provided in the voltage determines the maximum load current.
As the battery is charged and its voltage increases, the amount of current that the transformer wall can provide decreases. In this case, a battery voltage of 11.5 V and a corresponding output voltage 12V, maximum load current of approximately 0.5 mA is available. At the time of the battery reaches 13.8 V,a maximum of only about 250 mA. IC2 remains fully until the battery voltage reaches 13.8V. So IC2 reduces the charge current as necessary to maintain this battery voltage. At this point, IC2 is operating in a constant voltage mode. While IC2 is in the current mode of code, the voltage drop across IC is 250 mV, which means that the power dissipation is less than 0.2 W. Because of this low power dissipation, IC2 requires no heatsink.
While a lead-acid battery is charged at a constant voltage, load current continuously decreases until it reaches its final value, usually about 1% of nominal ampere-hour battery. By adjusting R2, this charger can be calibrated to correctly detect a fully charged battery with a capacity of up to about 10 Ahr. You can measure the load current and the voltage drop across R1. D1 turns on and shunts current around R1 when the voltage exceeds 0.2 V, which minimizes power dissipation in R1. Because D1, the voltage measured across R1 is correct only when the load current is less than 0.2 V. However, since the end of his tenure the detection occurs in the currents below 0.1 A, this range of measurement is more than enough.
IC1A, a differential amplifier with unity gain, shifts the voltage drop across R1 to produce a ground signal is concerned. IC1B compares this signal, which is proportional to the load current to a reference voltage set R2. When the load current drops low enough that the voltage at pin 6 of IC1B falls below at pin 5, the oscillations of high-performance and D2 turns on to indicate that the battery is fully charged. The best way to calibrate the end-of-charge detection circuit to let the battery is fully charged and then adjusted R2 D2 only to light up.
The best battery chargers for lead-acid battery is a voltage source current limited power sources on the battery until it reaches the point of tension. The shipper must provide enough current to keep the battery voltage to this value. To 12V, the lead-acid batteries, a voltage magnitude of approximately 13.8 V at 25 ° C is typical. However, the optimal set point voltage call depends on the temperature. Battery manufacturers recommend a CT scan of 22 mV /°C, so the charger voltage setting of the TC tracks the battery.
You can determine the state of charge of a lead-acid battery voltage and load current. When charging the battery with a voltage source set to 13.8 V, the charge current gradually decreases to a very low value when the battery is fully charged. The design in Figure includes a detection circuit that turns on full charge LED when the current falls below this threshold.
This design features a 12V charger, 0.5A wall transformer and a voltage regulator LM2941CT, IC2. The wall transformer provides regulated DC voltage of IC2, the circuit used to charge the battery and keep tension on 13.8V. R3, R4, and D3 through D12 set the output voltage regulator. R4 should be adjusted for an output voltage of 13.8 V with the battery disconnected. An important feature of any wall transformer load regulation is poor. For example, the transformer of Figure set to 12V when charged to 0.5V,but approximately 17 to 18 V without load. The design takes advantage of this feature, because it means that IC2 not require heat sink.
D12 D3 through negative-TC set out required to match the voltage of the battery terminal. Measurements of some 1N4148 diodes at 1 mA show a TC of 2.2 mV / °C, so 10V of these diodes in series to provide the necessary 22 mV / °C. R5 and D13 indicate the presence of power or when the battery is connected to the output and provide the minimum load required for IC2. Stabilizes C1 for IC2.
A battery has a voltage of about 10 to 12V. If you connect a battery charger output, IC2 fully active (saturated fatty acids) the pass transistor. Under this condition, all power leads IC2 possible to try to force the battery voltage to the reference point 13.8. Thus, while the battery is below 13.8 V acts, IC2 as a power source. The maxim that the wall transformer may be provided in the voltage determines the maximum load current.
As the battery is charged and its voltage increases, the amount of current that the transformer wall can provide decreases. In this case, a battery voltage of 11.5 V and a corresponding output voltage 12V, maximum load current of approximately 0.5 mA is available. At the time of the battery reaches 13.8 V,a maximum of only about 250 mA. IC2 remains fully until the battery voltage reaches 13.8V. So IC2 reduces the charge current as necessary to maintain this battery voltage. At this point, IC2 is operating in a constant voltage mode. While IC2 is in the current mode of code, the voltage drop across IC is 250 mV, which means that the power dissipation is less than 0.2 W. Because of this low power dissipation, IC2 requires no heatsink.
While a lead-acid battery is charged at a constant voltage, load current continuously decreases until it reaches its final value, usually about 1% of nominal ampere-hour battery. By adjusting R2, this charger can be calibrated to correctly detect a fully charged battery with a capacity of up to about 10 Ahr. You can measure the load current and the voltage drop across R1. D1 turns on and shunts current around R1 when the voltage exceeds 0.2 V, which minimizes power dissipation in R1. Because D1, the voltage measured across R1 is correct only when the load current is less than 0.2 V. However, since the end of his tenure the detection occurs in the currents below 0.1 A, this range of measurement is more than enough.
IC1A, a differential amplifier with unity gain, shifts the voltage drop across R1 to produce a ground signal is concerned. IC1B compares this signal, which is proportional to the load current to a reference voltage set R2. When the load current drops low enough that the voltage at pin 6 of IC1B falls below at pin 5, the oscillations of high-performance and D2 turns on to indicate that the battery is fully charged. The best way to calibrate the end-of-charge detection circuit to let the battery is fully charged and then adjusted R2 D2 only to light up.
