puffy lipo question...

I have read that when your pack starts to show puffing, it is reaching the end of its life span. Puffing is anything that is not flat. Slightly puffed will usually go away when you charge it, but will be back after it is discharged. Puffed is when the swelling remains after a charge and you don't get full capacity out of it. Really puffed, it will look like a balloon and be way too hot. You generally can't use it again when it gets to the really puffed stage.

Most people don't de-rate their stuff when they set it up. What I mean by that is you should buy things that you only use it to 75 - 80 % of it's capacity. Ex: If you have a 1000mAh battery, only use 800 mAh's of it. If you have a motor that draws 25 amps at full throttle, use a 40 amp ESC. If you do this, then your stuff will last way longer than if you don't.

If you use 100% of a batteries capacity every time, it will last maybe 40

- 50 charge cycles. If you only use 80% of a batteries capacity every time, you could get 200 charge cycles from it.

Vance Howard wrote in news:i6elkd$gkq$ snipped-for-privacy@news.eternal- september.org:

That's the thing. I have some batteries that as far as I recall were always a tiny puffy. I suppose they could have got that way from my bad use as these were back when I was still learning. But they've always worked good.

I asked because when I looked for pictures of puffed batteries all I found were pics of "balloons". But in discussions it seemed like some folks were referring to even the tiniest puffiness as a bomb waiting to go off.

I have a feeling there is no definitive answer, that there is a lot of information and misinformation floating around.

It would be nice to info from a contolled test. I can see how it could be done.

Brian

Now for some absolutely unscientific information. Our club field is way out in the sticks so one of the typical entertainment breaks is to shoot old Lipo packs with a 22 to see what happens. We have done it to about 30 packs. The battery pack is always charged up prior to execution. The results are pretty consistent. Packs that are not puffed up, when shot, will do everything between nothing and smoke a lot. Sometimes the pack will lay there for a long period of time with no reaction and THEN start smoking.

Packs that are puffed up will go up in a large, intense fireball when shot.

What does this mean? No. 1 - It's easy to separate out the bum shooters from the good shots... No. 2 - I no longer keep puffed packs for any reason whatever. They are dangerous. No. 3 - If you have lots of electric flyers and therefore lots of battery packs, storage represents a big problem, especially you hang on to packs until they are absolutely useless. Most people have far more batteries than they do storage containers. When you store 4-5-6 packs in a single container, that's right next to having a bomb in your workshop. When one goes up, everything in the container goes up. You will be very lucky if you only get the "lotsa smoke" reaction when a whole container goes up. I use vented ammo boxes and flower pots with a drip dish large enough to cover the top of the pot for storage. I use the Lipo sacks only to transport packs to and from the field. I don't believe the cheapo gray Lipo sacks from Ebay or other Chinese suppliers would contain a runaway Zippo lighter. After seeing the violence of the fireball explosion from our target practice, I doubt any of these storage systems would contain the energy of a massive failure of several packs going up. So, once again, if a pack starts showing any abnormality, get rid of it.

FWIW..................

I don't know what this means either, but it sure is interesting!

Like you, it makes me think I don't want any puffed packs around the house.

Good flying, desmobob

If you get puffing of a lipo pack, something is wrong. Best to retire it soon, if not immediately.

Why would it puff?

Typically I think it is from overheating caused by over working the pack. OR, it may be caused by a pack that is seriously out of balance so that some cells are being over charged and some are discharged too far.

Either way, I would replace it ASAP. If you choose to continue a very very slightly "soft" pack, then I would use it in a lower duty application.

If a pack is rated for 20C that means that is the LIMIT of its ability. I never run them at their C rating. I usually don't run them at more than 80% of their C rating and more often around 60% so I get better duration for the flight and longer life from the pack.

Ed

Ed Anderson wrote in news:4f5437d7-2862-4253-8e1c- snipped-for-privacy@w4g2000vbh.googlegroups.com:

I agree. I can only chalk it up to unintentional abuse somewhere in my learning curve on some older batteries I have that are a bit puffy.

Right now I have one battery that I can pretty much guarantee has never been abused in any way that I can tell, and it is not flat. I wouldn't say puffy either, but if you squeeze it, you get maybe at most a 16th inch squeeze before you feel the hardness of the cells.

BUT, I can't recall if maybe it wasn't already that way new. This is the one I use in my relatively new E-Flite T34. Nice flyer. It's a NRG 4S 3700 mAh 25C, labeled 92.5 amp continuous, 185 burst. It has always been charged on a Hyperion EOS 0606i at 1C. Also nice. It has been cycled 11 times. Maximum recharge has been 2938 mAh - ~80% capacity. (yes, I'm logging) ESC is a Castle Phoenix Ice Lite 75 - 75 amp max. Motor is an E-Flite Power 32 spinning a 12x8.

I also have the Castle Link data logging software and the max amps pulled that I find in my logs is 67 amps - 73% battery, 89% ESC - and that only during my initial run up tests before flight, about the only time I go full throttle.

I present this info for a sanity check. With this setup I see no way I could inadvertanly abuse this battery. I've been very careful with this setup since previous experience and what I've learned online.

Time will tell how it holds up as like I said it's only been used

Brian