Nimh question

[sadtimes]

I ordered some Nimh "d" size cells for my direct drive builds I am doing... When they showed up yesterday first thing I did was check the voltage on each cell... First pack all were right around 1.0v each... Second pack were all right on 0.9v each ...

I charged each cells alone at a 5 amp rate (hobby charger).... 2 of the first 4 cells took 1300-1600mah, the second 2 took 4000mah... I have to charge the second set when I get home tonight, and I will report back my findings.. also the resting voltage of the cells charged last night...

My question is this... Should I be worried, and return them, or is this all normal?

Oh, they are tenergy 10,000mah cells....

 

[jayflash]

Those are low capacities, which may have several causes besides poor quality.

I know the .5C rate is recommended, but that may be only for smaller cells and five amps is way too high for new cells not yet broken in. I'd discharge them all at a .2C rate or less to .9v -1.0v and try a break in cycle. Sometimes it takes several cycles at a low discharge rate followed by a higher charge rate of at least two amps. After that I believe it's recommended to limit the charge rate to two amps, but others may have better info for you.

Search around the CPF to find much detailed discussion on this topic.

 

[sadtimes]

Once I got home I threw another uncharged battery (by me since I got it, didnt have time to charge them all the first go round) in the charger and it charged to 4000mah and my charger shut down, which led to me hit restart (thinking this may have been a limit set by the charger) and voila, it took another round of 4000mah, for a total of 8000mah (back to back charges)..

So now I am going back and charging them all again to see what I come up with.. Still intrested in any and all input

 

[sadtimes]

Update:

I discharged 3 cells at 3amps (on factory settings for cut off of my charger) and then charged at 5amps.. the cells took 9700mah... I am happy now.