How can you test a battery to see if its good?

[Geeves]

I picked up some tenergy 4200,s as a backup set about a year ago and never put them in un til today. it fired up did the beeps then lasted for about 30 seconds then the motor started to do the clicking thing. Charged them up again and it seemed to work but still didnt last long 1 minute. I just bought a new charger onyx 240 and im charging at .5 amps. They charge for about 8 minutes each time. The charge only says it puts on about 600-800 mah before they hit their peak. Im new to this so any help would be great.

[roberzie]

Try charging them with a higher current like 3 amps and monitor batt temp.

[Fluid]

You are not charging them enough. If they are dead enough to run for just a minute, they will take a lot more than 800 mAh of charge. If they are almost dead and have not been run for a long time, do not charge them at over 1/2 amp; they need to be balanced and charging at a high rate will overheat some cells in the pack. If the charger goes off after 8 minutes, reset and charge again. The cells will not be fully charged until all the cells in the pack are warm to the touch when the charger shuts off.






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