How to make a battery charger?

Thread Starter

Qaisar Azeemi

Joined Oct 7, 2011
HI Friends;

Can any one please help me to make a battery charger??

I wana make a battery charger for two 12V dry batteries connected in series in my power supply to provide backup to load.


please tell me in general
1) how much voltage should i give to battery to charge.

2)should the voltage be continuous or full wave pulsuating DC.

3)please also provid the schemetic and links.

thank you very much in advance.


Joined Nov 24, 2008
If these are lead acid batteries in series you can trickle charge them with 26.84 volts. If kept at this voltage, they should not sulphate so you'd not need a desulphator circuit. (do a google search on 'desulphater'/'desulphator')

I'm guessing also that these are pretty big cells, but you do not need much current to 'keep' the batteries so an LM317 set at 26.84 volts would do the trick. If you need to charge these batteries from a deep discharge cycle though, you'll need something more substantial. At least for that initial recharge out of the depleted state.

Edit: I see you said dry cells. Then ignore my advise above. It would be helpful to know what technology the dry cells are and how they are constructed.
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