Why do Lipo Batteries "Puff up"

[E-Challenged]

Heavy current draw as in an EDF jet causes packs to get hot and puff before their time. Recharging packs immediately after a flight, when still hot, will also cause them to swell. Batteries are labeled some number and "C". When new, they may be as advertised, but with use, individual cell internal resistance (IR) gradually rises and their actual "C" may be much lower than advertised. A moderately swelled pack may work acceptably in a low current draw model with reduced performance and flight duration.

[rifleman_btx]

Awesome deal glad you still have them :Cool:

[BILLY BOY]

Yeah, the only problem with puffed packs is performance loss, you will slowly loose available amp capability as well as flight time. Otherwise no other issue. The only time I've ever seen an explosion was a rupture or a short that could be caused while charging. This is why you keep a close eye on your chargers and packs when charging

Thanks rifleman. Fortunately I was able to save the packs that I thought I had disposed of. I will hold onto them for awhile at least. I keep them in a fire resistant bag inside of my steel battery box. I should be safe. I had cut the leads off of the batteries but I was able to solder them back on and they are now charged and ready for the field. I don't fly any EDF or anything that would require any sort of extreme demands on the battery. Most of my flying is scale and very tame.

[rifleman_btx]

Yeah, the only problem with puffed packs is performance loss, you will slowly loose available amp capability as well as flight time. Otherwise no other issue. The only time I've ever seen an explosion was a rupture or a short that could be caused while charging. This is why you keep a close eye on your chargers and packs when charging

[BILLY BOY]

Primary purpose of the IR meter is to tell you the Internal Resistance of each cell.
There are plenty of pilots on this forum that can/will attest that a puffed battery is not an indicator of extreme danger or an eminent explosion.
The manufacturing processes and chemistry have improved from "years ago".
Google LiPo Internal Resistance to understand the basic fundamentals about the affects of climbing and out of balance IR's. ;)

Thanks for the info. I was told that keeping and using a puffed battery was irresponsible and asking for trouble. I am now a bit sick because I have disposed of three that I probably could have used.

[fhhuber]

Puffed will never deliver the max current you could get from an un-puffed pack.
It may not deliver the same capacity either.

I'd never put a puffed pack in a high demand EDF. But there are a lot of planes that don't demand as much current and can get another year to 3 years from a pack after its no good for the EDF.

[OV10]

Primary purpose of the IR meter is to tell you the Internal Resistance of each cell.
There are plenty of pilots on this forum that can/will attest that a puffed battery is not an indicator of extreme danger or an eminent explosion.
The manufacturing processes and chemistry have improved from "years ago".
Google LiPo Internal Resistance to understand the basic fundamentals about the affects of climbing and out of balance IR's. ;)

[BILLY BOY]

The only way you'll now for sure is to own an IR meter. If your in this for the long haul it is an invaluable tool to have just as much as a servo tester is. ;)

I have an IR meter but that will only tell you if the cell is good or bad correct? It will tell you the voltage of each cell and the total voltage of the cells. It was my understanding that a "puffed" battery is an extreme danger and prone to explode unexpectedly. This info was gleaned years ago from another RC site.

[OV10]

I was always told that to keep and use a "puffed" battery was very dangerous. They could explode and cause a fire. Because of this, I have always stored my batteries in a fireproof metal box. I just replaced 3 " puffed" batteries that seemed to work fine and were normal in every aspect aside from being "puffed" up. I hope I did not dispose of them needlessly.

The only way you'll now for sure is to own an IR meter. If your in this for the long haul it is an invaluable tool to have just as much as a servo tester is. ;)

[BILLY BOY]

I was always told that to keep and use a "puffed" battery was very dangerous. They could explode and cause a fire. Because of this, I have always stored my batteries in a fireproof metal box. I just replaced 3 " puffed" batteries that seemed to work fine and were normal in every aspect aside from being "puffed" up. I hope I did not dispose of them needlessly.

[Backer]

maybe is you charge it or discharge it really at a high C-rating, or post in some wrong place. you could find more lipo care guide at here: https://www.genstattu.com/bw

[Corsair 167]

Thanks for all the information.......................

[rtwatkins]

Puffing, or gassing, occurs when the temperature inside the battery gets to a point that it starts to boil the electrolyte causing it to gas. Rifleman is correct in that this will not only degrade the performance of the battery; and if done to the point that a rupture occurs you will have a thermal runaway... And a dreaded LiPo fire.

I would add that a good battery charger that has a balance charge is also a worthwhile investment. When a charger goes through a charge sequence, it charges the battery as a whole. A balance charge will look at the individual cells during the charge, and provide a load on the cell(s) as needed to ensure all are charging at an equal rate & amount.

[rifleman_btx]

Yeah, 3.8 is the optimal storage voltage, they are normally just as happy at mid 3.7-3.8. But at 3.7 yeah I would add just enough to get it into the sweet spot. My packs normally go a week between uses. And so far all my latest packs I've been flying with since I started correctly caring for them have been doing really well. Solid power, and consistent flight times with no sign of puffing up have kept me happy.

[F22trainer]

Good infor Rifleman...
I gotta watch my storage, as I usually keep them ready to fly. But they seldom sit for more than 3 days, before I run em’. Might be better to leave them at 3.8 until night before I go fly, eh?
I had 2 eFlite batteries puff but I worked them kinda hard on a few flights when I first re-entered the skies in January, I pretty much only use them as testers and short flights. Been using Admirals with no signs of puff and only had 1 or 2 “dead stick’ battery mistakes and they were at 3.7 V.

[rifleman_btx]

Much agreed, good times

[xviper]

Guessing the blue one, and probably will just take alittle longer for the HD to start to puff up. But I have a feeling of he keeps the treatment up, itll either puff or loose a cell before too much longer. I have buddies with puffed Graphenes. Yup multiple people. So for that price they want for them I wont buy.

You guessed right. The HD is holding up much better than the blue but it too, is starting to puff. I have quite a few well used Graphenes, some are getting toward 3 years old. I take care of them as best I can. Never drained below 3.7v/cell. Always charged at 1C. None have started to puff and all still perform quite well. I'll only buy Graphenes or HD, Gens Ace or Admirals.

[rifleman_btx]

Interesting, I've always found it the other way around. But maybe because of what I listed above in how I been running my packs after researching and understanding how to get the best longevity out of my packs.

[fhhuber]

The High C are less tolerant of abuse and known to puff under conditions that won't puff the old 20C to 25C blue wrapped packs.

[rifleman_btx]

Guessing the blue one, and probably will just take alittle longer for the HD to start to puff up. But I have a feeling of he keeps the treatment up, itll either puff or loose a cell before too much longer. I have buddies with puffed Graphenes. Yup multiple people. So for that price they want for them I wont buy.