battery fully charged indicator

Thread Starter


Joined Mar 13, 2009
Hi I have purchased a battery for about 20 Volts. I charge that battery for about 2-3 hours to make it work. But the issue is when I charge the battery using 12 volts adapter for more that 3 hours, The battery looks to be swollen. and I am afraid that it should bot explode.

I am looking forward to purchase or create a small circuit that will indicate the Battery charging capacity is full and would be great if power supply gets disconnected automatically.

Any suggestion / Advice would be appreciated. :)

Ranjit Vaity


Joined Feb 19, 2009
I'm confused on the 20 Volt battery and 12V adapter. Are you using an AC Adapter of lower voltage to charge the battery?

If the above is a translation error, I'll continue, What is the battery chemistry?

It should also be warm if it is swollen, it is being charged too fast or overcharged. If new and with proper charger, it could be defective.

The charge method and "full" cutoff varies widely between battery types, some are constant current, some are constant voltage, and the limits differ.