Lipo not so dangerous....

[Philistine]

So this has added to all the personal positive experience that I have had with Lipo.

Despite taking lipo cells to below 2.5v and then charging again (no problems other than swelling) - they got damn puffy don't worry about that, but I disposed of them at that point.

But look at this. My 12S 40ah pack started to have one cell that wouldn't charge over 3.8V (My pack is cell paraelleled), couldn't work out why.... broke apart the whole 40ah pack (made up of 10 6S8ah Zippy packs). Finally determined the dud pack through balance charging each pack, then started wondering why this pack might start behaving this way....

Looked underneath and Boom! Turns out the way I had reinstalled the sub pack into the ammo can's I use on my Yuba, meant that I had failed to put the aluminium base in, such that a screw penetrated a good 2 cm into the base of the pack.....

This is total penetration, and I charged this pack at 5amps on its own. No worries.

I just keep finding this battery technology to be so much more forgiving than people make out....

Not saying I haven't been lucky, but sheesh....

 

[neptronix]

Nice one!

luke also managed to drop one of this packs on a fast spinning wheel and tore the pouch material off, leaving the battery plates exposed to the elements, and nothing happened...

These do seem a bit impervious to puncture so far.

 

[liveforphysics]

I had a 28s 20Ah pack bounce out of its tray at 60mph(i forgot to strap it). It dragged along the tire and wore a 1/2in grove in the pack deep in the cells. Copper and aluminum foils exposed.

I tucked it back on the rack and kept riding.

Replaced the damaged pack later when i got home.

 

[Sunder]

I've actually found so as well.

I've had dented cells that still worked. I've overcharged to 4.5v/cell with so far seemingly no adverse effects (Not trying that again though).

I've had cells which arrived at 0 volts, which have charged back up without a fire (But wouldn't really hold much charge).

I've also shorted a cell for 30 seconds while assembling a pack. Made a hell of a spark, killed the cell - but again, no fire.

I'm not saying I also haven't been lucky. But it really doesn't feel like I'm holding a ticking time bomb.

 

[Philistine]

Sunder, when you say you killed the cell, you will probably find that just a tab blew, if you open the top of the pack (the shrink wrap), and see a blown piece of solder, resolder that, and your pack will be good to go again, I must have done that 5 times. PM me if you need a better explanation/photos.

 

[Sunder]

Sunder, when you say you killed the cell, you will probably find that just a tab blew, if you open the top of the pack (the shrink wrap), and see a blown piece of solder, resolder that, and your pack will be good to go again, I must have done that 5 times. PM me if you need a better explanation/photos.

Thanks, but no, the cell was definitely dead. I was trying to repair a pack, and this pack used a PCB with slots (But nothing else) to organise the tabs. Basically each tab was soldered with a HUGE blob of solder, and when I melted the solder, I wasn't holding the pack flat, and it ran into another cell. At first I dropped it and grabbed for the fire blanket, but then I saw it wasn't going to blow, so I quickly unsoldered it. By that time, a little over 30 seconds had passed though, and both cells involved died.

 

[neptronix]

I shorted a pack once too.

Solder jumped straight off the cell interconnection PCB.

The cells were not damaged in any way.
Seriously - hats off to whoever designed this stuff.

What i fear most are new cells that haven't had a discharge test ( while watching the individual cell balance to identify any funky cells ). Those are dangerous until proven otherwise.

Never heard of tested, non-abused cells ever going up in flames, so i don't lose any sleep over the 2.5kWh in my apartment.

 

[tef]

I will never touch a lipo again.

The bike with 2.4kwh of zippy lipo packs was not used for a week and always monitored (cell level) during charge and discharge.
One day at two o'clock in the morning, we had a large fireball in the garage.

I highly recommend using a fiberglass battery box for lipos.
I don't want to imagine what would have happened without it.

 

[hjns]

I will never touch a lipo again.

The bike with 2.4kwh of zippy lipo packs was not used for a week and always monitored (cell level) during charge and discharge.
One day at two o'clock in the morning, we had a large fireball in the garage.

I highly recommend using a fiberglass battery box for lipos.
I don't want to imagine what would have happened without it.

Wow, that looks like that has been a nice big plasma ball...
Any thoughts on what caused the lipos to ignite?

 

[neptronix]

That would be the first spontaneous combustion of a well known pack i've ever heard of.
Did you see any warning signs, IE could you see any cells puffing before?

did you cycle test all your packs beforehand? what voltage did you discharge down to often, and how old were they?

 

[Philistine]

That would be the first spontaneous combustion of a well known pack i've ever heard of.

I thought JohninCR had a Turnigy hardcase pack catch fire spontaneously? Maybe I got the brand wrong....

I will never touch a lipo again.

Pussy....


That was a joke :wink:

Frock me.... So you weren't charging, it just bust into flames like that spontaneously?

Sorry to hear about that mate, that is hardcore, glad you are ok though.

I think of all the stupid things I have done in my life.... maybe there is a god?....

Cackle cackle cackle....

 

[dogman dan]

Was the bike sitting on a charger, or just sitting? I'm assuming just sitting.

This is what I keep saying and saying. One of the reasons why my lipo comes off the bike every ride. I feel if it's hot, I see any damage, and storage is in a relatively safe place. Each steel box has about 800wh in it, so I don't burn up my entire pile of lipo in one event.

Im not afraid of my lipo, but a huge pile of it parked next to the wall of the garage is not done.

 

[tef]

Any thoughts on what caused the lipos to ignite?

I soldered the main discharge leads and paralleled the balance wires with the JST-XH plug of each pack on a stripboard.
Is it likely that a cell shorted "immediately" and got all the current from the paralleled cells?

Did you see any warning signs, IE could you see any cells puffing before?

did you cycle test all your packs beforehand? what voltage did you discharge down to often, and how old were they?

no puffing, no warning signs
I measured the capacity of each pack before I wired them together, no noticeable deviation.
In fact, they were new. I only did a few shallow discharges.

So you weren't charging, it just bust into flames like that spontaneously?

they were just sitting

Im not afraid of my lipo, but a huge pile of it parked next to the wall of the garage is not done.

The glassfiber box (prevented buring cells from flying around and was still in one piece after the fire), the fire extinguisher and the fact that I new about the risks and placed the bike in the middle of the garage, so that the wooden furniture was not directly beside it, saved the house.

 

[kfong]

Sorry to here about your lipo fire. I'm glad the fiberglass enclosure kept the fire from getting out of hand. I've been working on mine, but playing it extra safe by using carbon fiber. Your the first I know of with a large pack going off that had an enclosure that actually worked to at least minimize the fire. Was this only out of fiberglass and epoxy or was it fiberglass and polyester resin? Both resins burn so it's good to keep notes of this. I fear more fires, not less as we continue see people using lipos for ebikes. Especially when people start getting lax about safety. I tested fiberglass, kevlar then carbon fiber. Only carbon fiber was fire resistant enough not to vaporize under a torch. It's good to know the fire from these large packs don't reach such high temps when enclosed base on the photos you provided. Can you show more pictures of the fiberglass shell. This might help others who still use lipos to consider safer enclosures such as metal or composites.

The fire, was it due to openings in the case? Did you provide any vent holes? From the picture, it looks like the side might of popped open allowing for air to fuel a fire. I would rather loose a bike than a house. It's lucky you did not have it any worse than it could of been.

 

[bigmoose]

kfongs questions will help a bunch. Especially about air getting to the LiPos. The cashbox puncture experiment was vented enough to let the hot gasses escape, but appeared to not let enough oxygen in for a fire. So it appeared to be containment of the plasma ball and solvent vaporization caused by the stored electrical energy; but not augmented by direct combustion.

If this is true, we are moving forward on safer containment methods.

 

[Doctorbass]

That's an interesting discussion here. :wink:

I'm still thinking about returning to LiFePO4 or geting some of these EIG cells and leave my lipo for fire experiments outdoor :lol: still keeping in mind that the the only room i can keep them is in my garage wich is right under our bedroom .. I have Alot of smoke alarm all network connected and normal class extinguisher.. so i still dont feel safe enough.... But i know how to use lithium cells and have experinece with them... but we can't be 100% sure it's all safe.. and i like my house and would not apreciate having it burned down due to stupid lipo hazard !

btw, Would you all agree that discharged lipo is safer than charged lipo in regard of puncture? I think yes.

It would be interesting to have someone making an experiemnt with these ammo case and a lipo fire inside to see how well they can protect !

At least i can say that after two years of lipo use, i never had any fire and i always use them in a thight aluminum case and keep pressure on them to conteract the puffing effect and it work well!.. none of the 6s zippy pack out of the 16 i have have any sing of puffing from now. The lowest cell i have is at 4.55 Ah and the highest is at 5.09Ah. Their RI vary from 4 miliohm to 9 miliohm... but i'm using 3p so it's lower than that average.

Doc

 

[tef]

Was this only out of fiberglass and epoxy or was it fiberglass and polyester resin?

It was fiberglass and epoxy.

The fire, was it due to openings in the case? Did you provide any vent holes? From the picture, it looks like the side might of popped open allowing for air to fuel a fire.

I checked the cell voltages on a regular basis, so I did not attach the sidecover .

some pics:

 

[kfong]

The smoke is just as damaging as the fire. I know the residues are very caustic and can ruin a lot of equipment if not washed down. Looks like you may have more damage than just the bike. My friend took weeks to finally clean up his basement due to a lipo fire. He is a long time RC user and still had a mishap due to a faulty charger.

I went through the trouble of creating a breakout board using a DB 25 pin parallel port connector. I will be able to monitor the packs with my balance charger without having to open the case. With 25 pins I can go up to 24S.

Ideally it would be better to take the batteries out and store it in a fire proof area. I really don't see anyplace in the house I would want to store them since the smoke damage can be just as costly. During winter I have no choice since you don't want to damage the packs due to freezing. The garage is my only option in the summer, but having to remove the packs each time has its own safety issues. If such large packs can be safely contained on the bikes with a metal or composite enclosure and kept away from anything combustible. Then for me this seems the safest route. I can replace the bike frame, but not the house.

 

[izeman]

btw, Would you all agree that discharged lipo is safer than charged lipo in regard of puncture? I think yes.

especially for you i did puncture one of my puffed 0V lipos. see what happened:

http://contour.com/stories/lipo-punctured

 

[neptronix]

I thought JohninCR had a Turnigy hardcase pack catch fire spontaneously? Maybe I got the brand wrong....

Yes, he did. It was a brand new hardcase pack that was probably puffed but never got caught because well.. the hardcase.
A charge got put into it and it was left to sit.

This was a defective pack with no cycles on it and the defect showed itself immediately.
I had a pack like this that was shipped puffed, caught it, and prevented a fire.

What concerns me more is that a non-abuse case pack could just explode randomly.
That's when you're no longer in control.

 

[neptronix]

Any thoughts on what caused the lipos to ignite?

I soldered the main discharge leads and paralleled the balance wires with the JST-XH plug of each pack on a stripboard.
Is it likely that a cell shorted "immediately" and got all the current from the paralleled cells?

Did you see any warning signs, IE could you see any cells puffing before?

did you cycle test all your packs beforehand? what voltage did you discharge down to often, and how old were they?

no puffing, no warning signs
I measured the capacity of each pack before I wired them together, no noticeable deviation.
In fact, they were new. I only did a few shallow discharges.

No offense but, it sounds like you did not cycle test this pack to rule out the duds. Given that there is a 10% dud rate ( when i say this, i mean there is at least 1 bad cell in 10% of packs shipped ) you probably had at least 2 bad packs in there, just waiting to misbehave in some way.

Now i'm curious though, did you charge up to 4.2v per cell average? did you discharge below 3.6v/cell average?

To those who use lipo - imho i think you are putting your life into your own hands if you do not cycle test your packs. All RC Lipo packs are firebombs until proven otherwise. All it takes is 1 cell.

 

[neptronix]

Doc; puffing is a warning sign, and it also gives you time to respond to a failure that is just waiting to happen. When you remove that safety buffer, then you get a sudden explosion with no warning.

This is why i will never fully encase lipos. When they are puffed, i need to know.

Call me a lunatic, but this is how i roll.

 

[izeman]

...No offense but, it sounds like you did not cycle test this pack to rule out the duds. Given that there is a 10% dud rate ( when i say this, i mean there is at least 1 bad cell in 10% of packs shipped ) you probably had at least 2 bad packs in there, just waiting to misbehave in some way...

i think you just don't want the lipo fire topic to be true. you're looking for things ppl could do "wrong" just to believe you and your packs are safe.
no offense either. i tend to do the very same. but in case your home is in possible danger you shoud rethink.
on the other hand: there a MILLIONS of lipo packs sold and i don't think that there is a great chance the one I have, or the one YOU have will explode. but it could happen.
i punctured my puffed cell today - nothing happened, but there was no charge in it left.

 

[neptronix]

I'm not gonna dispute what you said - i am looking to remove the uncertainty factor of using RC Lipo packs. In every case i have seen, there was either abuse, or an untested dud that went off.

This is the only exception so far, and it is the only thing that has raised my eyebrows in regards to safety... of course i want to know more. It determines whether i advocate the use of RC Lipo or not.

I do have a stake in this, i have a super extensive RC Lipo tutorial/faq that i have been writing for almost a year now, which is about 90% done. I'd chose to not release this information if i find some instances where non-abuse/dud fires occurred..

...No offense but, it sounds like you did not cycle test this pack to rule out the duds. Given that there is a 10% dud rate ( when i say this, i mean there is at least 1 bad cell in 10% of packs shipped ) you probably had at least 2 bad packs in there, just waiting to misbehave in some way...

i think you just don't want the lipo fire topic to be true. you're looking for things ppl could do "wrong" just to believe you and your packs are safe.
no offense either. i tend to do the very same. but in case your home is in possible danger you shoud rethink.
on the other hand: there a MILLIONS of lipo packs sold and i don't think that there is a great chance the one I have, or the one YOU have will explode. but it could happen.
i punctured my puffed cell today - nothing happened, but there was no charge in it left.

 

[auraslip]

no puffing, no warning signs
I measured the capacity of each pack before I wired them together, no noticeable deviation.
In fact, they were new. I only did a few shallow discharges.

I'm guessing one full discharge to test capacity?
You might of missed a bad cell.
That or there was a short.

Lots of "what ifs."

There is no telling now. Pretty gnarly pictures.