450SE Lipo problem

[enfield55]

Hi,

I've got a T-rex 450SE with the stock ESC & motor, Hitec servo's on the collective, Futaba 401 & digital servo on the tail and 2 x DN Power 2200 Mah 15C batteries plus the stock align 18C battery.

After hovering for about 7 mins the ESC slows the motor down and I land. The batteries have never been below 10v after a flight and are a week or so old (5 cycles each say). After landing the batteries are warm to touch, but not hot.

The DN Power batteries appear to 'puff' at this point by a small amount, and after 5 mins, are all back to normal - feels like trapped air. The align battery is similar but not quite so 'puffy'.

Is there a way I can check the current draw easily (all I have is a multimeter) - is it kinda normal for a battery immediately after discharge to be a little swollen? I really hope 3 x new batteries are toast! BTW, they are charged with a e-station BC6 at 1A and no more than 1900 Ma has been fed back in during r-charge.

Any ideas welcome.

Cheers.

[enfield55]

I've found the problem. I was discharging the packs too much. The Align ESC cuts off voltage too low (around 65% peak voltage ~8.2V), hence the puffing. The packs I were using were taking 1800-1900 Mah to recharge - more than 80% capacity. If anyone is staring off like me, take my advice - with a similar setup fly for 5-6 mins tops and check the voltage. From that point (depending on your pack) it drops quite quickley and before you know it you'll have some fragged batteries... The max you should have to recharge a 2200Mah battery is about 1760Mah from what I've read... I flew for 6 mins today on one pack and it took 1460 Ma to recharge - there was no sign of puffing or excessive temp.

Cheers.