Why do Lipo Batteries "Puff up"

[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.

[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]

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]

Awesome deal glad you still have them :Cool:

[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.