I was strapping on one of my big CNHL 1100 mAh LiPos the other day, and the strap wasn't fitting like it should. I had just flown another of the same pack, so was a bit confused. Then I took a careful look, and saw what the problem was:



I've had a pack just stop working properly before, but I had never seen this. Now I know what a failing LiPo looks like. I currently have it sitting outside on the pavers around the pool.

I've never seen a LiPo fire before. I've seen videos of folks purposely puncturing one to start one. I'm kind of tempted to try that, but I'm sure the advice here will be to not do it. Yeah, I'm a 71 year old man, and I should know better, but there's still a kid inside of this old guy.

I understand that two ways to discharge a bad lipo are to connect a light bulb to it or to put it in a saltwater bath for a couple of weeks. I also understand that there is some debate about which way is best. Thoughts?

I assume it's not a good idea to discharge it with my charger, but I might try that with it outside.

I’m gonna tell you to not intentionally puncture it.

If you decide to ignore that advice, please get it on video.
And do it safely, far away from anything that it could damage, and keep 5 gallon bucket full of sand nearby in case you need to smother it, as well as an ABC fire extinguisher, and a hose in case that fire spreads.

If you want to be as safe as possible, discharge it via bulbs. There will still be some voltage left in the pack after that, so either connect it to a large resistor (I’ve got 4 ohm 250w resistors that I use as dummy loads for tube amps, but I don’t think you need something quite so heavy duty), or toss it in a salt water bath. Do all of this outside away from your home or other things that can burn.

You could discharge the entire pack via resistor, but, it’d take significantly longer. Actually, that might be safer than bulbs since it will discharge it slower.

https://oscarliang.com/lipo-discharger-light-bulb/

Edit- I think the debate about salt water baths is because there is a possibility of the connector tabs in the lipo corroding, and there being voltage left in the lipo that you can’t detect via multimeter because your main wires are no longer connected to the lipo internally?

If I were going to intentionally puncture one, I’d probably attach a nail to a long metal pole so that I could do it from a distance. I think I recall seeing a video of someone doing it in a metal ammo can, with a nail attached to the lid- they just stomped on the lid to puncture it. If you go that route, make sure you’ve removed the seal so the can can vent.

We shoot them with air riffles, but more often than not they only produce thick smoke, to get one to light on fire you should over charge it.

Personally I would just keep flying it, but that’s just me, more sensible people will tell you to dispose of it responsibly, so you should probably do that, yes connect a light bulb or if your charge has it, use the destroy setting (but put it somewhere safe while doing it sss over discharging them can also set them on fire).

OK, Since you ask..............

Every week I handle between on average 300-400 LiPo battery charges (at least 150 on a Thursday Sept to July).  Doubt many people do that! 

Packs from 6S 5000mAh down to 1S 150 mAh.  (I have 12S helicopters, 2x6S 5000mAh per flight)

Makes me likely the most "experienced" or the most foolish, your call.

I have always (since LiPo appeared way WAY back now) used immersing them in a saltwater bath for at least two weeks. The water permeates throughout the battery, cell packs are NOT waterproof. Thus the conductive points are all over the battery internals from the cells to output plate to the internal tracks. 

A connector getting corroded has never stopped the discharge here, so I have stopped testing for 0v as when I did, after two weeks immersed in a strong saline solution secured away from property and wildlife intrusion, they were ALWAYS effectively zero'd.  

My council have batteries as a separated out collection service for all battery types as long as they are in a clear plastic bag marked batteries.  THEY treat as if still charged, the lorry has a fireproof "safe" box.

I suggest you review very closely your system of inspection, storage, charging and use. After all my use I have NEVER had a pack get that bad instantly, there have been warning signs of swelling to be seen earlier than that.  If it DID get that way suddenly, then there's NO safe way to continue to use it.  Don't listen to the little forked devil on your shoulder................ HE's used to fire.

And if you do puncture it, and it does not burn, you likely now have an even more dangerous item to dispose of, but hey your life, just don't increase the risk for unsuspecting others.

We share a site with Airsoft, those generally ignorant anti-social cretins use LiPO, and think it quite OK to dump them and flammable aerosols in an oil drum marked up and used to break down and dispose of bulky damaged balsa airframes.


Just Saying.................................  

I mean, if they’re gonna put it in a fireproof box and treat it like it’s charged anyway… I don’t know that I’d go through the trouble of discharging it.

Our trash pickup here doesn’t have separate LiPo pickup, anything in or near the trash can goes into the trash truck and gets compacted. Real good way to start a fire, and I don’t want to be responsible for that. So, I don’t throw away a battery- regardless of its voltage.

We have various places (staples, Home Depot, etc.) that have battery and electronic recycling boxes- so my batteries go in them. I figure if I’m putting it in the appropriate box and following their directions, I’m not liable for anything.

(12-Aug-2023, 10:50 PM)IanS Wrote: Personally I would just keep flying it, <snip>

It's not the flying I'd worry about so much, but the charging.

From the reading I've done, it appears that a good way to minimize chances of a LiPo fire is to not charge batteries with obvious physical defects, like the bulging mine has.

I'd kind of like to see a LiPo fire, so when people ask, "Have you ever seen a LiPo fire?", I could say yes. But I don't really want to see one start when I'm charging my packs!

(13-Aug-2023, 06:34 AM)Bad Raven Wrote: Every week I handle between on average 300-400 LiPo battery charges (at least 150 on a Thursday Sept to July).  Doubt many people do that! 

Well this is the part of your post that got me most interested. Now I need to check out some of your posts to see what you're into to go through so many packs! Do you charge packs for other people?

Or are you counting each cell in those counts, in which case fifty 6s pack charges = 300 "LiPo battery charges"? So fifty packs per week is about 7 packs per day. I'm flying most days and averaging maybe 4-5 6s packs per day, so that would be 24 to 30 cells per day or 168 to 210 cells per week.

(13-Aug-2023, 09:32 AM)aerokam Wrote: Well this is the part of your post that got me most interested. Now I need to check out some of your posts to see what you're into to go through so many packs! Do you charge packs for other people?

I run an after school club, that is 150 upwards 1S cells every Thursday, then maybe 75 more for Friday FPV with the more skilled kids. Batteries ALL handled by me.  Thats usually after a morning session just for me.

I also co-run an Indoor adult flying club which is Quads/Helis/Planes.  That is fortnighly and a bigger hall once a month.

I personally fly 13-15 packs pretty much every time I go outdoors, and I aim, weather provided, to fly outdoors 4 days a week minimum.  Mostly 1350mAh 6S if quads, but some 1800 4S and 1100 4S. Also some micro so 660-750 1S.

2200 3S and 4000/5000 6S if Helis.

2200 3S/4S - 4500 4S with planes.  If I'm training youngsters (with my equipment and batteries) that's maybe up to 10 of 2200 3S in a two hour session on top of my own flying.

Then ADD indoor/garden late pm and evening most days, min normally 6, often 10 cells.  Might do an afternoon and an evening session.

I never charge on site.

Nah, don't fly much at all really.......................  

I have had one 150mAh 1S smoke when its connector shorted with a twisted wire (kid rough handling). I actually exploded a 250mAh 1S many years ago when stupidly I'd "lost" it in a multi charge lead, didn't realise it was there, and plugged in a 6S to charge it!!     (That was the last day I used multi connector type charge leads!!). That just went bang and vapourised, no fire, little smoke!!   Only damage was to underwear.  

(13-Aug-2023, 09:25 AM)aerokam Wrote: It's not the flying I'd worry about so much, but the charging.

From the reading I've done, it appears that a good way to minimize chances of a LiPo fire is to not charge batteries with obvious physical defects, like the bulging mine has.

I'd kind of like to see a LiPo fire, so when people ask, "Have you ever seen a LiPo fire?", I could say yes. But I don't really want to see one start when I'm charging my packs!

I always charge in one of those fireproof batt boxes, well worth the money.

I’ve only ever had one battery go bad while charging, and this was a relatively new (4 to 5 cycles) completely unmarked undamaged battery from a three lettered brand (that I’ll never use again).

Luckily the extremely strong metallic smell tipped me off so I just unplugged the batt box and took it outside and left it there for a few hours until the battery cooled down, put it on kill setting and let it do its thing.

I know I’m not the only person to have that happen to me with that brand.

Funny thing is, the fixed wing pilots in our club (I fly both quad and FW btw) are the absolute worst for battery safety, I’ve seen some batteries so swelled they barely fit into the battery bay of their Tundra and seen many a very-near-fire as a result of bullet connectors being plugged into the wrong polarity, but oh no you walk through the pit hut with a not even powered on quad in your hand and you’ll be up on a disciplinary if they got their way…

At the end of the day just do what you feel safe doing, if you don’t feel safe using it chuck it in a salt bath and leave it there for a week and it’ll be no bother to you again.

As part of my charging routine I check each pack as it is charging. Feel for temperature, look for any bulging or change in the size/shape, and confirm charging parameters. When the “finished charging” alert is heard I unplug the pack, again feel temperature and examine the size/shape and set the pack aside for 10-15 minutes. After that I use a small cell checker to confirm (I know a cheap checker isn’t necessarily totally accurate) overall pack voltage and individual cell voltage. If anything doesn’t look or feel right the pack gets a saline bath and properly disposed of.

I’m not paranoid just cautious

I have a new battery pack (Pyrodrone Graphene 6s 1100mAh 75C) with 5 or 6 charging cycles. Two of which were storage cycles. I checked the pack with my little checker and its alarm sounded and it showed C2 to read 0. All other cells showed good.

I have no idea why one cell would deplete to 0. I’m hoping to hear back from Pyrodrone soon. For now I’m down to two packs to fly with. Grrrrrrrrrr