Lead Acid Battery Charger

Lead Acid Battery Charger

Parts & Description:

R1=120 Ohm C1=10uF/25V T1=NTE374/Tip32a

R2=82 Ohm C2=10uF/16V T2=NTE123AP/BC327

R3=10K D1=1N5401/NTE5801 U1=LM350 or LM317T (On large Heatsink!)

R4=33K D2=LED (Red, 5mm)

R5=22K

P1=2K2

Unlike NiCad Batteries which require a Constant current source for recharging , Lead acid batteries need a constant voltage source as the circuit here provides ,

Except for use as a normal Battery Charger, this circuit is perfect to 'constant-charge' a 12-Volt Lead-Acid Battery, like the one in your flight box, and keep it in optimum charged condition. This circuit is not recommended for GELL-TYPE batteries since it draws to much current. The above circuit is a precision voltage source, and contains a temperature sensor with a negative temperature coefficient. Meaning, whenever the surrounding or battery temperature increases the voltage will automatically decrease. Temperature Coefficient for this circuit is 8mV per °Celcius. A normal transistor (T1) is used as a temperature sensor. This Battery Charger is centered around the LM350 integrated, 3-amp, stabiliser IC. Output voltage can be adjusted with P1 between 13.5 and 14.5 volt. T2 was added to prevent battery discharge via R1 if no power present.

My prototype built to test the circuit , including ammeter in series with the output so that i can monitor the charge process ..Ken

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	Lead Acid Battery Charger Parts & Description: R1=120 Ohm C1=10uF/25V T1=NTE374/Tip32a R2=82 Ohm C2=10uF/16V T2=NTE123AP/BC327 R3=10K D1=1N5401/NTE5801 U1=LM350 or LM317T (On large Heatsink!) R4=33K D2=LED (Red, 5mm) R5=22K P1=2K2 Unlike NiCad Batteries which require a Constant current source for recharging , Lead acid batteries need a constant voltage source as the circuit here provides , Except for use as a normal Battery Charger, this circuit is perfect to 'constant-charge' a 12-Volt Lead-Acid Battery, like the one in your flight box, and keep it in optimum charged condition. This circuit is not recommended for GELL-TYPE batteries since it draws to much current. The above circuit is a precision voltage source, and contains a temperature sensor with a negative temperature coefficient. Meaning, whenever the surrounding or battery temperature increases the voltage will automatically decrease. Temperature Coefficient for this circuit is 8mV per °Celcius. A normal transistor (T1) is used as a temperature sensor. This Battery Charger is centered around the LM350 integrated, 3-amp, stabiliser IC. Output voltage can be adjusted with P1 between 13.5 and 14.5 volt. T2 was added to prevent battery discharge via R1 if no power present. My prototype built to test the circuit , including ammeter in series with the output so that i can monitor the charge process ..Ken Back To Model Electronics page