How to evaluate battery

[majorpat]

Is there a prefered method and tool that will evaluate a batteries suitability for continued use? What we find is that our LiPo's charge and balance fine and prior to and afterward they check fine with a test meter but during the actual running some of them seem to lose their power.

1) How would you load test them and with what type of device is used to test?

2) We use 2s or 4s batteries and charge with a HI-Tech Quad charger.

If you need more info from me let me know.

Thanks

[Shooter]

If you have a data logging ESC, you can study the voltage drop while under power. This is a good indication of pack condition. You will need a reference though (i.e. what voltage drop was achieved when new). Another way is to apply a load such as a light bulb and measure voltage with and without the load. If you measure the current as well, you can calculate internal resistance. There are some very helpful youtube vids out there.....do a search on youtube for internal resistance.

[TheShaughnessy]

Get a Hyperion or thunder power charger, they measure resistance and will help diagnose tired cells

[pescador]

The Powerlab chargers measure IR as well, but I just picked up an ESR (IR) meter from ProgressiveRC, touch the button and get an instant IR reading for the whole pack or each cell individually.