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lipo ballooning


wickedgeezer

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i wouldnt charge it again if i was u, i wouldnt want it near me mate. i had one do it to me the other day n i looked on here n most people say the battery has come to the end of its life.

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Swelling of more than 1-2mm is a sign that they are WAAAAAAAAAY overworked and shouldn't be used again. What packs are they? It sounds like its possible that they are fake, and aren't 5000mah 50C (more like 5000mah 15C or 20C).

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With LiPo chemistry cells there is an extremely thin polymer that separates the Cathode and Anode.

cell_config.jpg

If this separator splits due to the cells swelling then you will have a dead short inside the pack.

What happens after this dead short really depends on a few things like how much energy (charge) the cells have, where they are and luck.

At best you will have a lot of heat and smoke (the smoke of which is HIGHLY corrosive) at worst you will have a fire.

There is no hard and fast rule for how much the pack can swell before this separator splits, i've seen 1 pack at the flying club swell to almost twice it's size and the bloke is still using 6 months on.

I've also seen a pack swell only a few mm and go up in flames.

So it's really 100% your choice and decision on if you want to continue using it or not.

If you do i would mark it up and treat it like an egg till you dispose of it, as the separator will no doubt have been severally weakened and and something as simple as strapping it down or it banging about in the boot of your car could cause it to fail.

With regards to why it failed, 100% agree with the previous posters.

The cell has had more current drawn out of it than it can comfortably give, so it's swelled.

I certainly would not use that cell for that application again, as if it swells again the chances of a fire will go up dramatically.

another thing worth mentioning is that, if the pack has been stored fully charged this dramatically reduces it's C rating.

So you could easily have a pack that's worked fine for 6 months, but each day it's stored fully charged it's ability to give current is reduced (C rating) to the point where it can no longer supply the needed amount of power.

That will not get better only worse, so using it for the same application will only cause exactly the same thing again.

Personally i'd stick a lamp on the terminals, leave it outside in a bucket of sand for a couple of days (well away from anything flammable) then take it to your local recycling centre to dispose of it.

But for me seeing a £500+ RC car burn for the sake of a £30 battery doesn't warrant the risk.

Cheers

Mark

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