Parallel Lipo Question

[wayoutwill]

I made a mistake by connecting two 11.1v 3100mah lipos in parallel when one was partially discharged and the other was full. The partially discharged pack puffed up somewhat, about 1/5th larger and got pretty warm. After the two were connected for about 5 minutes I noticed the swollen pack and disconnected. I let the battery sit for a while, outside, and then recharged slowly. It seems to be OK except for the deformation.

My question is: Will it be safe to use this pack again or is it dangerous? Right now, it is fully charged and balanced but is still puffed.

[dhkites]

DO NOT USE THIS PACK. The pack is damaged and should not be used. I've seen one of these packs explode and believe me it's not worth the risk.

[brgsstm]

http://www.youtube.com/watch?v=KpUXuEg3fNE

Says it all!

[stevehickey6]

i was thinking of joing 2 trex packs for my ikarus eco 8

they are 3s 2200mah 15c packs

i have made lead up so that they are positive to positives and negatives to negatives is this in serial or parrallel i always get mixed up :)

anyways when i conected them together and put multimeter across it was showing as one pack ie 11.1v area of voltage not 22.2 so its correct voltage i wanted :)

i have not yet connected them to my eco 8 to test them

but after reading this post i am now to scared to incase one pops :(

they are brand new batteries only used each one once on my trex

i gather from post above that if one pack is a bit lower voltage or a bit higher than the other this will cause my pack to blow up is this correct ?

or did you just have a bad pack and this was reason for it blowing ?

am i safe to connect my pack to eco 8 if one pack is a bit lower than other ?

[WillJames]

That is parallel. If you fly them in parallel, make sure and charge them together in parallel as well.

[stevehickey6]

hi thanks for your reply

my charger only charges 3 cells so i can not charge them together as they would be 6 cells

my charger auto charges a pack to full then stops i think so if i charged each pack seperate to this level then i should be ok ?

thanks

[Pinecone]

NO, if they are in parallel, they are still a 3S pack. The limitation of chargers is voltage, which relates to the SERIES count.

Of course, your charger may not be able to handle a full 1C rate (amps) for the 3S2P pack you are charging.

In parallel mAH increases, therefore so does C rate for charge and discharge.