I would like to build a charger for rechargeable batteries.

I have 4 x 2700mAh 1.2 Volt batteries. I would like to build a charger.

I am looking for a circuit diagram if any one can help.

Thank you

 

You can use an LM317 regulator in constant current mode,but you would be better off buying a ready made charger from the internet,cheaper.

 

Thanks very much. Living in Zimbabwe sometimes its easier to make than buy.

 

Well you would still have to buy components . What do you already have available or can you get locally? Any other charger (e.g. car battery charger)? Transformer? .....?

 

Very true ! um we tend to make thinks as if they pack up we can theoretically fix them. I have a solar panel with a current output of 0.199Amps, I also have a circuit already built using a LM317 for adjusting the voltage, I use it as a regulator on a solar panel for charging a 7Ah battery, I know it has no current limiter. I have no idea what the charge current is but suppose its limited by my solar panel at this stage

 

here is a constant current charger using anLM317, adjust R1 to set the best current charge rate, put a 100 Ohm preset in for R1.

 

Thank you having read the information my 6 volt 1 Watt 0.199Amp solar panel will not be enough to charge these batteries, am I correct.

I have a 16 Volt transformer, if I was to use this after rectifying and smoothing would I need to put a 12 Volt regulator before the constant currents controller.

Many thanks

 

You wouldn't need a 12V regulator. 16V RMS will give about 21V across the smoothing cap. An LM317-based constant-current source can be provided from that. What is the tranny rated output current (or VA rating)?

 

If you are building a constant current source from LM317, you will also require some heat sink... its not the most efficient current source and can heat up quite a bit...

 

You could always charge your batteries in parallel instead of in series if they are single batteries. But, your solar may not be enough to charge them if they work every day.
Nickel batteries are kind of hard to charge fast so most inexpensive chargers charge overnight at low current on a timer.