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Aug 26, 2007, 07:50 AM
Registered User
Discussion

Want bent lipo pack straight?


Hi

I had a crash with my plane, the battery is an evo 20 2500 mah lipo.
My question, Can these lipo packs be "ironed out flat?"

The battery is in perfect health and did not even puff after the crash, it's a bit wrinkled up and i feel like ironing it flat so you get that out of the shop look again, can this be done?

How can i get it flat and straight again? (using a mild iron setting?) The pack does not fit well after the crash

Any help will be much appreciated thanks!

Pete
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Aug 26, 2007, 07:53 AM
Magicsmoke maker
Inflexo's Avatar
Hallo Pete, hoegaan dit? (nie lekker nie )

I'd suggest NOT trying to iron the pack out. What'll happen over the next few weeks most likely is that the pack will puff out as air/moisture creep into tiny tears in the sealing seams. If you're going to try flatten it out... it'd have to be done reaaaaallllllyyyyyy sloooooowlllyyy - and in a very safe place.

Paul
Aug 26, 2007, 11:45 AM
Registered User
Die lipo packs is duur hier by ons, kan nie net weggooi nie
Dankie vir jou opinie.

The pack has been sitting for almost 3 weeks and no puffing, i tell you i'm going to straighten and "un-wrinkle" it anyway somehow, i can't be the only one that wants to do something like this?? Or does everyone else fly with perfectly fine busted packs,
after a crash or two?

Think about it this way, if the battery can take a 100 km/h impact
to get it into the shape it is now, undamaged, then why should a carefully planned way of bending, ironing or whatever make it more dangerous, except for if unseen damage is already done and moving things now might make things worse, i'm nor betting on the last part for i want to fix this lipo, any advice i can get here will be a bonus. the pack has full cpacaity, no leaks nothing weird happening to it, perfect but busted.

Thanks

Pete
Aug 26, 2007, 12:03 PM
Space Coast USA
hoppy's Avatar
Have you measured individual cell voltages?
Have you measured capacity at 1C discharge?

What may seem to be undamaged may very well be damaged. I have a perfectly flat non-puffed lipo with a slightly crunched from end. It charged up fine but would not hold voltage. It would lose 20% of it's voltage overnight.

I'd check out the "real health" of that pack before proceeding and I'd do it in a firesafe location charging the pack with a balancing charger.
Aug 26, 2007, 03:10 PM
Permanently Banned
the internal matrix of the LIPO to insure low Z has been disturbed , it won't be the same as before and the minute creases will develop into an open tear as it heats up and cool down during contraction

and when one cell goes FLAT to ZERO VOLTS, U' ll be charging a 2S instead of a 3S as before and the semi good cells may erupt becuz of overvoltage charging
Aug 26, 2007, 03:20 PM
I'm a Registered User
I would NOT use any heat to try and smooth the wrinkles.
Aug 26, 2007, 09:01 PM
Retired CAD guy
birdofplay's Avatar
I just bent some 1650ma 3s1p lipo's myself

I have NOT let then into the House/Shop/Garage since.

The good wires and connector were removed and the rest

TOSSED OUT ! ! ! never to return to my doorstep !
Aug 26, 2007, 10:53 PM
Registered User
Not too much encouragement is see here, that's fine i understand,
these packs are dangerous, i cannot expect a go ahead attitude, my lipo balancer shows all cells are charging equally constantly so no bad cell. Maybe i should rather "clamp" it into shape rather tha ironing it, though if the material covering the "lip chemicals" the silver, can handle pack heat, i don't see why ironing it with a mild setting can be that bad, obviously being very carefull, and jump for cover if there is any sign of puffing.

I'm not going to do this now, i need time and patience for this, i need to go to work in a couple of minutes, anyway i'm still going to do it, wish me luck !
Aug 27, 2007, 10:13 AM
Fan of pusher multirotors
Tachikoma's Avatar
Do not iron it!
Are you out of your mind? You do NOT apply a hot metal plate to a LiPo!

Try SLOWLY straightening it out with a non-heated surface. Do it outside, wear fire-resistant gloves (and protective goggles if you have them) and be ready to jump away at the first sign of trouble.

However, do consider that while one slight bending might not be enough to ruin the pack, unbending it can cause further stress and kill it.
Aug 27, 2007, 11:19 AM
Registered User
Good, i did it. The pack is smoothened out and straight enough to fit in my new fuselage. Now it only needs ironing. Just joking.

Thanks for the word of caution. The pack was indeed punctured, i applied a piece of old lip pack cell covering to the small puncture and loctite it into place, no problems, no hassles. And i'm ready to fly again.
Aug 27, 2007, 11:32 AM
Space Coast USA
hoppy's Avatar
IMO, it's too early to say no problems, no hassles.

Have you measured the capacity of the restored pack at 1C discharge?
Have you checked to see if any cells are loosing voltage after a few days?

I hope you keep us informed of what happens with that pack. Those that have gone before you have all reported the packs failed in a short time. It will interesting to see what a bent/punctured pack does.
Aug 27, 2007, 11:51 AM
Frequent Flyer
wattsup_kz's Avatar
I had a 2S 1200 etec "classic" in the nose of my PCW that bent into a slight U shape from too many nose-ins. I was able to carefully straighten it by hand and return it it service (using extra caution with storage, transport and charging).

It worked fine for another year until it no longer could put out the current without dropping voltage below LVC. I don't know if the failure was due to the bending, or storing it fully charged. That was in 2005, before I found out about proper storage.
Aug 27, 2007, 01:24 PM
Fan of pusher multirotors
Tachikoma's Avatar
Happy you managed to straighten it, but:

Quote:
Originally Posted by pete2194
The pack was indeed punctured, i applied a piece of old lip pack cell covering to the small puncture and loctite it into place, no problems, no hassles. And i'm ready to fly again.
This pack is not reliable anymore.
If it had only bent then I could believe straightening it would get you back on track, but punctures in LiPo batteries are very very bad, and almost always fatal to the pack in a short while. Air and humidity have already gotten in the cell, and even if it isn't dead yet it is very likely it'll be very soon.
Hope it goes out quietly and not with a bang.

If I were you, I'd store this pack outside, in a place where if it does blow up it won't damage anything.

What you can do is to dismantle the pack, toss the punctured cell and build a smaller pack from the remaining one(s).
Aug 27, 2007, 02:13 PM
Permanently Banned

Danger


The Puntured Cell Will Go Flat To Zero Volts By The Time U Need To Charge It
Aug 29, 2007, 11:08 AM
Registered User
I Appreciate all of your comments, the puncture was very small. at the tip's edge (no visible gap between the white chemical and the covering at that very small tear), it's sealed now, though through what you all are saying,
it's not easy to tell yet, i have not charged or done anything to the pack yet, i'm having long hours and a busy week at the job unfortunately.
I'll check how well the charge holds on the weekend, it has held up pretty good so far, through all the caution that i received here, nothing bad has happened, 50 % there, maybe the other 50% of the problem will creep up to realize the possible problems above, hope not, let's see what happens, i'll keep you all posted on the results.

Let's hope for the best, thanks all

Pete
Last edited by pete2194; Aug 29, 2007 at 11:20 AM.


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