Lipo Balance charging

[PJC]

I am new to Lipo and have two new 4600mAh 45C Lipo batteries.
After running each pack in a five minute race I then balance charged them at 4.6 amps, both needed the same capacity to charge them (approx 1200).
One set took 20 minutes to charge , the other over 90 mniutes. Any reasons why that might be. Does one pack have a problem? Is there a way to test it?
:confused:
I didn't notice any problems while running the car.

[Beanie]

Hmmm...what was the balance like on both batteries? Perhaps the one that took longer was rather out of balance? Did you review the cell voltages to see if they were balanced on both packs during charging?

[PJC]

No, I all I did was place them on a balance charge and let the charger do its thing. I'll try that on the next balance charge though. Should I be checking the voltages of each cell regularly, after each run say?

[Beanie]

Well everyone has their preferences but I'm pretty anal with Lipo's!

Personally, I always balance charge at 1C each time, and put the lipo sitting in a metal biscuit tin for safety(Making sure it doesn't short it). Then during the charge I usually just check the temp of the battery occasionally to make sure it's not getting warm and also look at the charger menu option that shows you the voltages of each cell in the pack, to ensure they are balanced.