Odd Lipo Puffing.... Then unpuffing... Advice required

[Andy_Ran]

Sorry to ask about lip-os as i am sure its been done to death.

I cranked one of my 500's out yesterday for the first time this year.

I had the lip-os in a storage charge all winter, after only about 10 cycles each. I fully charged them 1 week ago but couldn't fly due to weather etc. I totally forgot they where charged and didn't put them back to storage.

Yesterday I got my heli out and went for a easy fly (basic circuits etc), timer was set to 5 mins (6.5mins was what i had flown before with a resting voltage of 3.75v per cell )

After about 4 mins i brought the heli down, and the Li-po had puffed up quite a bit and had gotten really hot (never happened before) I checked the heli over for any binding or stiff-ness etc it was all OK, motor and ESC where all still cool as well. I popped another li-po in and had another easy flight and next pack (again same age) was fine. The 3rd pack did the same as the first.

I left them for a few hours in a safe place and came back to check, both packs had a resting 3.76v across the cells (all very close per pack) and they have totally unpuffed and gone back to normal.

Has any one got any ideas on why this happened? are these still OK to use, any pro-cautions i can undertake to check the packs.

[rachel]

Not sure of the make ?? but if they are Optipower , pop them back to Andy , as their service is second to none and he will check them out for you.

If not opti's then it depends on how much they puff ?
If they come down looking like a sausage roll , bin them !!!! (using the proper channels , a screwdriver and a phone camera )

Hope this helps x Rachel

[Andy_Ran]

Thanks Rachel. It wasnt my Opti-power ones. They where relativity inexpensive ones off ebay from the land of the rising sun.

I would say they puffed by about 8-10mm from the standard height (6s Lipo)

[rachel]

[QUOTE=Andy_Ran;1020406]Thanks Rachel. It wasnt my Opti-power ones. They where relativity inexpensive ones off ebay from the land of the rising sun.

I would say they puffed by about 8-10mm from the standard height (6s Lipo)[/QUOTE

So hard to say , but I can feel by flying that a lipo has gone off if they are hot , puffing , or down on power I would replace them a burning model is no fun :-(

[steve_b]

If they're puffing like that, and more importantly coming down really hot, then bin them.

You can get Turningy jobbies from HK UK Warehouse for ~£30 delivered, and there's no way you'd fix a burning 500 for that

[Andy_Ran]

I think thats the route i will go down

Thanks guys

[cjcj1949]

If they get too hot they will catch fire. Hard to say when, as the temperature inside is what counts, as that's much higher than outside. If it is only temperature they you could use them to charge newer lipos. They won't get warm on a 5amp discharge.

[Andy_Ran]

Ordered a few new Lipos - Great price from HK!

[cjcj1949]

The Blue ones are good, not fantastic, but usable.