# solar charger controller

#### ayane

Joined May 3, 2009
39
i was wondering if the circuit http://www.national.com/ds/LM/LM150.pdf on page 10 is able to charge a sealed gel type lead acid battery.. 12v and 4AH..

I have 6 solar cells connected in series adding to ( voltage open circuit : 18v and short circuit current: 0.8A) ...

was wondering whether i can use the solar cells to charge the lead acid battery using the circuit above..thx..

Any1 can help me?

#### k7elp60

Joined Nov 4, 2008
555
Yes you could, but there are a number of circuits that are much less complicated. In fact there is an IC that is design especially for that. It is a PB137.
The data sheet is attached.

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#### Bernard

Joined Aug 7, 2008
5,228
A voltage regulator will drop to much V. With a reverse current prevention diode between panel and battery, monitor current and voltage, all you might need is a V monitor to disconnect panel when battery is charged. Max power out will be when panel is loader down to an output V @ about 7/10 of open circuit panel V. On graph V willbe about same. I X 10 = your panel +_.

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#### ayane

Joined May 3, 2009
39
thx for all your help..i start to patch the circuit..

By the way, was interested to know whats the minimum input voltage to this PB137 IC?..

#### k7elp60

Joined Nov 4, 2008
555
thx for all your help..i start to patch the circuit..

By the way, was interested to know whats the minimum input voltage to this PB137 IC?..
If you mean for it to regulate the output for charging a 12V battery: Then the answer is about 15 volts. The data sheet has several charts that show the performance of the IC.

#### ayane

Joined May 3, 2009
39
1. hey thx for the help...I was wondering how can i add protection features to this circuit?..

Or some features such as detecting whether the solar cells are providing enough voltage or current to charge the battery?...

2.I had also found a circuit which charges a 12v lead acid battery..

http://ludens.cl/Electron/12Vcharger/12Vcharger.html but the problems lies the low efficiency about 50 percent..

Any suggestions on how to improve the efficiency?.

3. Lastly i am not quite how sure the charger circuit below works..Any can help me thx?

The circuit http://www.national.com/ds/LM/LM150.pdf on page 10 is able to charge a sealed gel type lead acid battery.. 12v and 4AH..

#### ayane

Joined May 3, 2009
39
Anyone can help me? As i am a bit lost. By the way i am doing this for my school project.

#### fanie

Joined Jan 20, 2007
63
Ayane,

The first thing kids should learn at school is not the facts - that one can learn any time in your life. The first thing they should learn you is how to do things for yourself other than being spoon fed. If you don't learn that then you are always going to be depending on someone else.

Read up on it then post back when you think you have a solution.

#### ayane

Joined May 3, 2009
39

I think the operation amplifier is comparating the voltage of the battery with a reference voltage based on the term hysterisis?

The reference voltage is set by the 3 resitor R2, R3, R4?..

The diode act as a protection from reverse-flowing of the battery

R6 will be the current sense resistor of the battery..

#### Bernard

Joined Aug 7, 2008
5,228
As suggested on page 3, did you measure charging current & voltage with every thing connected? For protection try a 14V shunt regulator.