Unmarked Battery

[rivergreenmachine]

I bought a used plane and the guy gave me two batteries, but one of them is a Li-Po that has no markings on it. It's an 11.1v 3 cell

The plane was the only plane he ever owned and the "labelled" battery is a 2200mAh 11.1v Li-Po. This battery measures 4" x 1-1/4" x 7/8".

The unmarked battery measures 3-3/8" x 1-1/4" x 7/8".

Is there any way to determine the mAh? If not, what is the safe way to charge this battery?

Thanks for any help with this.

[larkshead]

Based on the size comparison to the 2200 mAh battery, the unmarked one is probably a 1600-1800 mAh. A fully-charged 1600 mAh battery can deliver 1600 mA for 1 hour before becoming discharged. (Under ideal conditions - and we all know there's no such thing.)

Any battery can safely be charged at the 1-hour discharge rate. So, you should be able to safely charge this battery with a 1.6A or smaller (balanced) charger. Using a 1.6A charger, this battery would take an hour or so to charge.

Most batteries can be charged at a higher rate, but without the manufacturer's documentation, you can't be sure.

Regards,
-Peter

[rivergreenmachine]

Thank you for the response Peter! I'll set my charger for 1600mAh to be safe.

[flydiver]

There's a lot of old myth about lipo charging. Most of it is based on NON-balancing chargers from a few years ago. If you have a BALANCING charger you can likely charge at 2C or 3C for most any lipo without a problem....IF your charger has enough amps to do the job. Some new lipos can charge at 5C. Lots of cheap chargers simply will not do the job.

If this is an old lipo without balancing port then a slow charge certainly won't hurt it and is advisable. Without the right charger or measuring tools you are only going to be able to guess what the the actual capacity is. Size and weight are decent indicators.

If it does not have a balancing tap it is so old as to be pretty suspect in terms of reasonable use.