How puffed is puffed?

[DrJustice]

I have two new Align 2200mAH 18C batteries. Both packs were slightly ballooning from new, and when cold I can depress the plastic wrapping ca 1.5mm. When hot they are a bit more ballooning, there's markedly more pressure inside and I can depress the wrapping ca 2mm.. So there's definitely a gas pocket inside - my other batteries are rock hard. I've run these Align batteries 3 cycles now, discharging them down to ca. 3.85V per cell.

My questions are: Are these likely to be puffed packs? Is a gas pocket acceptable at all? Could the gas pocket simply be trapped air?

My dealer didn't seem too concerned, but have agreed to "look at them" if I send them back. If they're actually puffed, I suppose they should not be put in the mail for safety reasons.

DJ
--

[BenHeli]

I've seen fire with puffed LiPo so any kind of puffing to me is no good.

[redgiki]

I wrote a really long description of what happens inside a LiPo battery to cause puffing, but I desisted because I realized it would lose just about everybody.

The puffing is caused by free CO2 and free O2 inside a battery. It is a result of poor quality control (excess water) at the factory, high heat, or natural over-time degradation of the anode and cathode. Some small amount of sponginess is common in even the highest-quality LiPo batteries as they approach the second half of their useful life, and when the battery gets warm it may be a little more prominent.

Any visible puffing when cool, though, should be regarded as a warning sign. Your battery has either been abused (run too hot or over-amped), or there was poor quality-control at the factory.

As far as the Align 18C batteries go, they are well-known on many forums to be defective in any discharge capacity. They simply were mis-marked as being much higher discharge than they are, but good luck getting Align to honor a warranty on their defective battery. And they'll likely replace it with another run from that same factory with poor QC.

[DrJustice]

I wrote a really long description of what happens inside a LiPo battery to cause puffing, but I desisted because I realized it would lose just about everybody.
I'd actually be very interested in that...

Any visible puffing when cool, though, should be regarded as a warning sign. Your battery has either been abused (run too hot or over-amped), or there was poor quality-control at the factory..
OK, this is what I wanted to know. I will not agree to send these batteries back in the mail due to safety reasons then. It'll be an interesting case this...

As far as the Align 18C batteries go, they are well-known on many forums to be defective in any discharge capacity. They simply were mis-marked as being much higher discharge than they are, but good luck getting Align to honor a warranty on their defective battery. And they'll likely replace it with another run from that same factory with poor QC.
Hah! They haven't spoken to me yet - I tend to not give up with cases of defective or wrongly specified goods ;)

Thanks redgiki - a most useful reply!

DJ
--

[Baine31]

To add a little here; try to use a charger that will give you internal cell resistance measurements. As the resistance increases inside the cells with age and use, the discharge rating of the pack effectively lowers exponetially. Hence, a new pack rated for 25C with an average internal cell resistance of 6 milliohms will provide much lower than 25C when the cell resistance begins to climb to 30+milliohms. The pack will become increasingly hotter each time you discharge it until the cell resistance is so high that the amp draw from your gear overloads the batteries ability to keep up with it and poof, Lipo fire.

Essentially, higher cell resistance=harder for the pack to dump it's load :YeaBaby:

When this begins to happen, packs get hotter and hotter during discharge degrading them and raising cell resistance further and further, thus the cycle is self feeding.

BTW, ANY puffing during/after discharge is a good indicator that the cells are racing up to meet death. Puffing during charging is ESPECIALLY dangerous and your best bet is to disconnect the pack or watch it VERY closely until it finishes charging.

-Keep em in the air!

[helicraze]

I believe the pack is measured at meg ohm

[Baine31]

I believe the pack is measured at meg ohm

Not to be a "hair splitter" or anything but lipo pack resistance is measured in mili not mega.

[helicraze]

Sorry, you are correct, little m not big M!