LiPo Battery Bubbling Up

[BrettJ]

I am new to the LiPo technology and I just got a TREX 500. I am running two Flightpower EVO 25C 2170Mah packs in series. The last flight I had, I noticed that one of the packs had one of the cells in it looking like is had expanded and bubbled up. I was just hovering around getting a feel for the chopper. It was pretty hot but it cooled off and charged to full capacity. Is it OK to fly? Will it blow up the next time I fly?:bomb:

[istandalone]

how long was your flight? are you timing them to be sure to use only 80% of cap or less? do you balance your packs?

[BrettJ]

I flew til the speed controller started pulsing. Then landed. I am using two packs in series and one of them was hotter than the other. The one that was hot had one of the exterior cells puffed up and mushy. After it cooled I charged it to full cap and after a few hours it seemed to have shrunk back to its normal size and solidity. I am using a Titan Jr with the Flight Power Balancer to charge it. From now on I am going to fly shorter flights and set my timer to do so.

[Cliozeek]

I have been running (2) Thunder Pwer 2070mah 11.1v batteries in series and I always get one battery to discharge completely before the other one. Any suggestions as to why? Its always the pack that connects the positive to the speed controller, I've flip flopped the packs and same result each time. Flight times are very short as well as it seems that I'm only operating on one pack.

[istandalone]

usually, when the esc starts pulsing (low V cutoff) it's already discharged too much. you really should time your flights, and then look at how many mah is put back into the pack. if you're using a 2200mah pack and 5 minute flights pull 1500mah, then you know you can go a bit more. stick to the 80% rule, and you should be golden. for your 2170mah packs you should use no more then 1736mah. an eagletree v3 or similar device is priceless when careing for expensive lipos.

[BrettJ]

Thanks a bunch!!! I am working on calculating my Mah usage. :noteworthy

[michael503]

I am new to the LiPo technology and I just got a TREX 500. I am running two Flightpower EVO 25C 2170Mah packs in series. The last flight I had, I noticed that one of the packs had one of the cells in it looking like is had expanded and bubbled up. I was just hovering around getting a feel for the chopper. It was pretty hot but it cooled off and charged to full capacity. Is it OK to fly? Will it blow up the next time I fly?:bomb:

are these 2 packs the same age and condition? If not, a hard run will kill the weaker pack.

[BrettJ]

Both of the packs are 25 flights old. I have had 3 more flights with the two batteries in series.....down to 80% and everything is good. Not to hard of a thrashing but some full power manuevers and the batteries are equally discharging and running fairly cool. Thanks:thumbup: