What causes a lipo to puff?

[McKrackin]

I don't know if it did it or not but it's the only difference.

I don't think they were actually puffed anyway now.Just air between the pack and the shrink wrap like a hot air ballon...

I've had some of the guys from RR tell me of similar times.
Shrink wrap is just too airtight ;D

[19000rpm]

Hot air balloon? Wouldn't that cause the heli to float away? ;D

You know that makes sense. Air trapped might explain why my pack doesn't seem damaged. It came in at 12.59 with no apparent loss of cell capacity. Another mystery solved...Except for the gyro part... I'll go smoke another Padron and sip another martini and I'm sure something will come to me. ;D ;D ;D

Happy landings

[McKrackin]

I'll be smokin',drinkin' and thinkin' myself ;D

[BTCat]

My Hyperion puffed up like a toad, but it seemed like trapped air to me also. Of course, I have zero experience with puffed packs. It performs perfectly even though it has been like this for a couple of months.

[19000rpm]

BT are you saying the Hyperion pack stayed puffed? Mine went down to normal size when the battery cooled.

Happy landings

[akent]

Aug 23, 2009 19:53:00 GMT -6 BTCat said:

My Hyperion puffed up like a toad, but it seemed like trapped air to me also. Of course, I have zero experience with puffed packs. It performs perfectly even though it has been like this for a couple of months.

A co-worker who flies a Trex 450 gave me a puffed pack to dispose of. It was a fairly new pack, but the heat in Houston ruined it. It was 106 the day he brought his stuff to the office and left it in his CAR!!!

Anyway, I drained the battery on my charger, cut off the deans connector and proceeded to play with it!

There is something a bit spooky with these batteries. I thought that you could just poke it and let the air out. Nope. I cut it open with an exacto and it sparked and spewed smoke with every draw of the knife! The smoke smelled odd, too. Not like an electrical smoke.
So, I poked and prodded and it never did give up the poof.

I then dropped it off at my friendly neighborhood radio shack.

These things are weird.

I have puffed four batteries now, I think from the heat.

But, I wonder how much damage is done to these by leaving them fully charged for a long time?
A couple of the batteries that puffed on me were not used hard and the temps were barely 100. They puffed, but not seriously like the one I had from Houston. These are just 'kinda' poofy. Like a few millimeters of air got under it's skin.
I'm still using them. They seem to still have the same capacity.

I too would like to know what makes these things puff.

We know this:
1. High temps.
2. Over discharge.
3. Over charge.
4. Too high current drain.

But, what about those that puffed that didn't have any of the above applied to them?
Kent

[BTCat]

Aug 24, 2009 5:29:54 GMT -6 19000rpm said:

BT are you saying the Hyperion pack stayed puffed? Mine went down to normal size when the battery cooled.

Happy landings

Yep. I played around with it today. Still as puffed as ever.

[akent]

All of my puffy batteries stayed that way, too.

Now, sadly, I have a 3300 6s 30c puffer. I think it was a combination of too much heat and drawing it too low with the ES600..Bummer!

I wonder what would happen if you shoot one of these things?

[Solitaire]

Aug 24, 2009 20:47:24 GMT -6 akent said:

I wonder what would happen if you shoot one of these things?

Sounds like you're just about to do that. ;D

[19000rpm]

OK, I still don't understand how a gyro causes a puffed pack.

What I think I undsrstand, maybe ;D , is that there are 2 kinds of puffing: 1) Air trapped in the pack. 2) A chemical reaction. I believe I've experienced both kinds.

My air puffed pack goes back to normal. My chemically puffed pack didn't and earned a trip over to Radio Shak.

I won't be using any chemically puffed packs. You never know when it might fail causing a crash or fire.

I don't believe I'll be probing any packs with sharp instruments. A mounting screw punctured a pack on my corsair when the motor quit and crashed. That thing caught fire and ruined the whole plane. The fire looked real scale though. ;D

Happy landings

[r/c basher]

What would happen if a lipo puffs, but you have a zip tie around the pack not letting it puff would it like, explode? Because when I fly my hbfp and g2 I have a zip tie around the packs.

[19000rpm]

r/c, I don't think an air puffed pack would explode, but that might not be the case for a chemically puffed pack. Just hard to know for sure. You could use a velcro strap or heavy rubber band to hold the pack. I think either of these materials have enough stretch.

Happy landings

[rtfheli]

You don;'t want the chemicals to leak out. The metal wrapping around each cell is somewhat flexiable, but if you tie down the cells, ou might restrain the puffing, but pressure will increase quicker when flying and may cause that explosion a lot quicker.

Be careful.

[akent]

Interestingly, I discharged two of my puffers on the charger to the storage charge and then put them on the shelf for a week.
The puffing actually went down by a lot, but not completely.
I recharged them and they stayed less puffed.
I wonder how much these don't like being fully charged all the time?
Kent

[Dave]

I'll tell you one more thing that will make these babies puff and that is a strong case of the dumb ass.

Last night after going to the lhs and getting them there deans connectors me and a beer sat down at the work table and started the conversion. Well me and the esc got into our second beer when I started to solder everything back together. On the third beer thought I would hook everything up and check it out to make sure all was good and this is when the sh&t hit the fan. You have never seen an old man move so fast in your life, keep in mind that we are now on our third bud and to boot this is all taking place in a bedroom on the second floor of our house. Like I said earlier we are on our third beer when I decided to go for a quick test hookup and the excitement started........smoke coming off the lipo you talk about messing up a good buzzz.....turns out that somewhere around the second and third beer I hooked up the positive to the negative and the negative to the positive.....guys this just don't work ;D. You talk about puffing that thing swelled up like a sore.....you know and was looking for a place to explode .

Everything turned out OK, battery checked good this morning, puff has gone down some.

Bottom line don't drink and solder cause you may puff ;D

Dave