Lipos loosing power fast

[maltydog]

i have 7 2100 mah 11.1V packs and a couple 800mah 11.1 volt packs that i have had since about feb - march of this year. i have always used a balancer / charger (FMA cellpro, duratrax ice with the triton balancer, blinky, etc.. for the last two months i did not use the batteries much (doing planes) but i did charge them up and balance before storing. the last couple days i've had tried using them in my trex and electric plane. several of the batteries loose power after about 45 sec to one minute like they are depleted. if i stop for about a minute then they seem to have full power again but only last for about 15 to 20 seconds. when i put them on the cell pro all the cells show about 4 volts. in other words doesn't seem that a cell is bad; they seem to be reasonalby balanced. several other batteries work ok.

the only thing common about the bad batteries is that they ar DN brand. plus they seem a slightly bit puffy but maybe not. what the heck is wrong with these batteries? do they just need to be cycled a few times? i didn't think you needed to cycle lipos. out of a total of 11 packs, 5 are having this problem. out of the good ones, 3 are non DN packs and 3 are DN packs but they are the newer packs (purchased in late march / early april). I am not bashing DN batteries, i am just stating facts to see if anyone can shed some light on what is going on with my batteries. the packs probably have about 15 - 20 charges on them each.

gw.

[odieser]

you are suppose to store lipos only at 50% charge
fully charging and leaving them for months may be your error
I am no expert on this though just what I have seen in the forums

[Rodan]

I have four DN 3s2100 packs that I've been flying regularly since Jan. They are beginning to show similar power loss, but not quite as bad as yours. I think mine are just at the end of their life... :dontknow

Are your newer DN packs that are having problems the 20C? I have heard these packs have had issues... Mine are all 15C, so I can't comment on that from personal experience, but there's a lot of talk about them in the TRex section.

Mine are starting to get a little "puffy", and I notice a significant power loss after 1-2 minutes of flight. Full collective will bog it badly, but it will continue to fly...

I figure I got my money's worth out of them, but will probably replace them with better packs, as the demand on my packs has increased as my flying skills have improved...

[maltydog]

yes, all are the 20C packs. i was reading an article in RC Heli this morning about this and the article said it may be posssible to bring them back to life with a few charge / discharge cycles. the article also stated to store them with nominal voltage (similar to what odieser posted).

well, lesson learned.

gw.

[Pinecone]

Also there was a bad batch of the 20C packs, that the importer Xus Hobby will exchange.