Battery Charger Questions

JhonDoe · 10th February 2010, 07:30 AM

Im am searching for a project to smartly charge my lead acid battery and i found this circuit..

can someone explain to me how was th OP amp working in this circuit?
what was the function of R1 in this circuit? im planing to employ a pass transistor to get more current out of this, is it possible?

Anthony C Smith · 10th February 2010, 07:45 AM

without values its hard to tell, I would guess u2 is a comparator with positive feedback to give hysteresis, and R1 would allow a trickle charge current when u1 (presumably a 317 regulator) is turned off or has voltage reduced (again without the values can't tell)
as for pass transistor, why not use the 3 or 5 amp version of the 317?
suggest you try simulating this in ltspice

cliffforrest · 10th February 2010, 07:53 AM

It may be that the circuit will not "start" without R1.

A sim will help.

JhonDoe · 10th February 2010, 07:56 AM

sorry i forgot to include the values..

R1 1 500 Ohm 1/4 W Resistor
R2 1 3K 1/4 W Resistor
R3 1 1K 1/4 W Resistor
R4 1 15 Ohm 1/4 W Resistor
R5 1 230 Ohm 1/4 W Resistor
R6 1 15K 1/4 W Resistor
R7 1 0.2 Ohm 10 W Resistor
C1 1 0.1uF 25V Ceramic Capacitor 104
C2 1 1uF 25V Electrolytic Capacitor
C3 1 1000pF 25V Ceramic Capacitor 102
D1 1 1N457 Diode
Q1 1 2N2905 PNP Transistor
U1 1 LM350 Regulator
U2 1 LM301A Op Amp

Im thiking that this circuit is a smart charger that i can connect my battery at home while im at work without worring to overcharge it. i was just thinking if it is possible to add a pass transistor to provide a lil more current for bigger batteris..

JhonDoe · 10th February 2010, 08:07 AM

i dont have a simulator software yet, and i dont even know how to use them, what was simulator software are you using? and were can i get one?

Forgot to tell you guys that im not good in electronics. but i know some basics..

Rolf Zetterberg · 15th February 2010, 08:08 AM

This is where it comes from-makes it easier to comment if you have the full article in front of you:
Car Battery Charger

10th February 2010, 07:30 AM	#1
JhonDoe diyAudio Member Join Date: Jan 2004 Location: ac	Battery Charger Questions Im am searching for a project to smartly charge my lead acid battery and i found this circuit.. can someone explain to me how was th OP amp working in this circuit? what was the function of R1 in this circuit? im planing to employ a pass transistor to get more current out of this, is it possible?

10th February 2010, 07:45 AM	#2
Anthony C Smith diyAudio Member Join Date: Jun 2005 Location: Sunderland	without values its hard to tell, I would guess u2 is a comparator with positive feedback to give hysteresis, and R1 would allow a trickle charge current when u1 (presumably a 317 regulator) is turned off or has voltage reduced (again without the values can't tell) as for pass transistor, why not use the 3 or 5 amp version of the 317? suggest you try simulating this in ltspice __________________ Anthony C Smith MAES MinstSCE -I think rain is wet so who am I to Judge-

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10th February 2010, 07:53 AM	#3
cliffforrest diyAudio Member Join Date: Sep 2004 Location: UK	It may be that the circuit will not "start" without R1. A sim will help.

10th February 2010, 07:56 AM	#4
JhonDoe diyAudio Member Join Date: Jan 2004 Location: ac	sorry i forgot to include the values.. R1 1 500 Ohm 1/4 W Resistor R2 1 3K 1/4 W Resistor R3 1 1K 1/4 W Resistor R4 1 15 Ohm 1/4 W Resistor R5 1 230 Ohm 1/4 W Resistor R6 1 15K 1/4 W Resistor R7 1 0.2 Ohm 10 W Resistor C1 1 0.1uF 25V Ceramic Capacitor 104 C2 1 1uF 25V Electrolytic Capacitor C3 1 1000pF 25V Ceramic Capacitor 102 D1 1 1N457 Diode Q1 1 2N2905 PNP Transistor U1 1 LM350 Regulator U2 1 LM301A Op Amp Im thiking that this circuit is a smart charger that i can connect my battery at home while im at work without worring to overcharge it. i was just thinking if it is possible to add a pass transistor to provide a lil more current for bigger batteris..

10th February 2010, 08:07 AM	#5
JhonDoe diyAudio Member Join Date: Jan 2004 Location: ac	i dont have a simulator software yet, and i dont even know how to use them, what was simulator software are you using? and were can i get one? Forgot to tell you guys that im not good in electronics. but i know some basics..

15th February 2010, 08:08 AM	#6
Rolf Zetterberg diyAudio Member Join Date: Aug 2005	This is where it comes from-makes it easier to comment if you have the full article in front of you: Car Battery Charger

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