lipo cells

[wbridge]

hi another crazy question, ivejust brought a new saddle pack and used it barely a few times, now i went to check them today before my racing sunday and there is a tiny ammount of bulging from the casings, what is best to do?


thanks in advance

[wbridge]

i should mention i stored them fully charged , but now im discharging them slightly to see if the small ammount of bulging goes down

question is are they still safe to use?

[Lee1972]

Best advice is don't store them fully charged as this will cause them to swell. I generally rotate our packs during racing and if we're racing outdoors and have limited power supply I'll charge them up the night before. Any packs unused on the day when I get home I'll put on a storage charge cycle.

[wbridge]

will discharging them reduce the swelling? its not much to be honest ,i can still clamp them in the car, and there new so id like to save them if i can , if its not to risky to use then ok, ill just not store them again fully charged

[mattr]

Originally Posted by wbridge

i should mention i stored them fully charged

Why? That's in the beginners guide to LiPos, store with a storage charge or after they've been used............

Originally Posted by wbridge

question is are they still safe to use?

Quite probably. I've run very slightly/just visibly swollen cells for months. When they go properly, its painfully obvious. Can't get the battery strap down, the side of the case cracks etc etc. You just need to keep a close eye on them. Check after every run/charge type thing.

What sort of cells are they (brand/capacity) as i've found that the really high capacity cells have a lot more "stuff" inside them, so even a very very slight swell, that is perfectly normal, can make the case look dodgy.

[wbridge]

because i just did what i have done with lipos for a long time, never had a problem before , and there 6000mAh 80c 22Wh cells

so higher capacity than my others, ill keep them on storage when not in use from now, other wise ill keep using them and a good eye, right now ive put them down to storage , so i would guess they will be ok

[mattr]

I would suspect that most of your other lipos are also swollen in the same manner, except you can't see that as the case hasn't budged!

[wbridge]

i would guess the same thing, so im going to put them all on storage, i guess they will be ok (others still work ) , feel bit stupid but lesson learned

thanks

[mattr]

Oh, btw, 6000mAh is probably 2s3p, so there will be 3 cells in each half of the saddle, go much below 5000 you are into 2s2p, hence the less crowded cases!

[SlowOne]

Nothing will take the swelling away. It is caused by a release of gas due to a micro-short inside the cell. As Matt says, you can keep running them but they will be down on power and not as good as ones that haven't swollen.

If you run stock classes then get rid of them; you'll be down on speed and acceleration. If you run modified classes they'll work fine (just motor up to restore speed) and if they swell any more then retire them and dispose of them.

To retire them, fill a bucket with a salt-water solution, drop the cells in and leave them there for a fortnight until flat. Then take them to your local recycling centre and put them with the batteries pile.

There rest has been said - store at the right voltage (roughly 3.7 to 3.8v per cell) and cycle them once every six weeks or so back to that voltage. You know what happens if you store them fully charged...! HTH

[wbridge]

yes the point is taken haha, oops, well as ive said lesson learned and ive just ordered new ones to replace them should i need to, but ill use the ones i was talking about and if it gets worse ill retire and be rid. i guess i did not notice before for obvious reason (now)

thanks for putting me in the right direction , feel bit stupid for this mistake but its appreciated

[Lee1972]

Originally Posted by wbridge

yes the point is taken haha, oops, well as ive said lesson learned and ive just ordered new ones to replace them should i need to, but ill use the ones i was talking about and if it gets worse ill retire and be rid. i guess i did not notice before for obvious reason (now)

thanks for putting me in the right direction , feel bit stupid for this mistake but its appreciated

We all make mistakes it's part of the learning curve, did a similar thing a couple of years ago charged packs up to go racing couldn't make it and then went on holiday returned to racing three weeks later and found some of the packs had puffed wasn't a happy bunny. Still use the packs now but always charge in a lipo bag

[SlowOne]

Don't feel stupid, it's life. Come back on here and ask anything you like, that's what we are here for.

Always learn from other people's mistakes; you won't live long enough to make them all yourself! HTH

[mattr]

Originally Posted by wbridge

feel bit stupid for this mistake but its appreciated

No one died, batteries didn't explode, don't worry about it.

[wbridge]

indeed, im still going to keep them , but i have replacements now just incase