Test rechargeable NiMH battery

I have a large batch of NiMH batteries, however not all of them seem to be in best of shape. I have deviced the following plan to seperate the good from the bad, and would like to hear any comments if this isn't a good approach. All batteries are NiMH and around 2700 mAh.

1) Charge battery fully in charger (I have an official charger) 2) Measure initial battery voltage 3) Connect battery to a load of about 2 Ohms, current will be between 0.6 and 0.7 Amps, drain battery for 30 minutes, monitoring current and voltage every minute this is supposed to draw around 300 mAh from the battery, which is a bit over 10 % of the total capacity 4) If the battery can't deliver the above it's broke, otherwise I hope it's safe to assume it will be allright; if voltage from the battery drops very quickly, it will likely indicate it's broke

Cheers !


From the charging / discharging curves your can learn allot, maybe you can monitor/log the voltage over the Cell's with the arduino and log it to a terminal and plot it to a excel graph.

Thank you for your reply. Yes, that is exactly my idea. My questions are perhaps better phrased as:

What are good indicators my battery has gone bad / is still good if I have this (U,I,t)-graph ?

Is discharging for 30 minutes - about 10 % of capacity - enough or should I push further?

Don't know :~ , I would refer to google , i know Varta has some good documentation , and prob other manuafactur's also.

Try http://batteryuniversity.com/