This is a simple circuit for charging Lead- Acid type car batteries. It has an added temperature sensor control using a BD140 transistor. This is an important feature to extend the life of the battery cells. The charger has a current of only 3 Amps so this is not intended for charging really dead batteries- just if you want your batteries in optimum charged condition.
Gell-type batteries however are not compatible with this. Link
3 Responses to “Lead-Acid Battery Charger”
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Great post as usual, long time lurker here, first comment! Thanks for the great blog.
This is a simple circuit for charging Lead- Acid type car batteries.
Only recently I went to electronics’s shop to buy a new charger which will charge other than AA size type batteries. I bought this digitor universal NiCd/NiMH charger. Before connecting it to the wall plug I noticed the charging instructions saying that AA type 1000mAh should charge 12 hours, or, AA 1700 mAh (max. size mentioned in the brochure) need 21 hrs. Well because all of our rechargeable batteries we use around the house are 2000mAh or bigger, and a quick calculation for 2400 mAh suggested I would have to keep these charging for almost 2 days, it got to me the product must be outdated now days. Reading your sentence “Some really cheap battery chargers are, in fact, dangerous.” I must agree, this one doesn’t even turn the actual charging auto-off, it has to be done manually and, as the instruction also mentioned a battery might burst when overcharged I went to the shop again to buy another one that turns charging off automatically, then keeps in the trickle mode, plus is much quicker. Does also 9V size for fire alarms around the house.