sandal

I have two 1700 mAh 6.6V LiFe receiver batteries. According to the instructions, one can be charged at 4C and the other at 5C. My charger is a Thunder T6, capable of providing 5A. My question is, how long should it take to charge a battery? The first stage of charging (constant-current) only takes a few minutes at 5A, but the second stage (constant-voltage) where the charge current gradually decreases to 0, takes more than an hour. Even on the "fast charge" setting, where charging is supposed to stop when the current reaches 1/5 of the initial setting, it takes a long time. Another thing I have noticed is that cell voltages stay within 0.03 of each other during the first stage of charging, but as soon as it hits 7.2V and the C-V stage starts, cell voltages fluctuate up and down, with as much as 0.2V difference between cells. Both of my LiFe receiver batteries show this behaviour during charge. My 2-cell and 3-cell LiPos do not, however, and LiPos take shorter time to charge even if they are charged at 1C (vs. 4C for the LiFes).

Is this normal behaviour for LiFe batteries? Is my charger broken? Any comments or advice are appreciated. Thanks.

raptureboy

My experience is they take a little longer than lipo's and depends on charge rate and how far out of balance they are. At 1 C it should take 1 hour but usally takes 1-1/2 hrs. When finished the cells should be no more than 1/10 of volt different. Lot's of good info here http://hangtimes.com/a123_batteries_for_giants_faq.html