Lipo safety

[Philistine]

If you fully seal the pack, you just made a flaming shrapnel grenade.

Where was the shrapnell in the video? looked like an ideal outcome to me.

I have a 12S 40AH lipo pack in 40 cal ammo boxes on my Yuba, and I have 20S 20ah in my Greyborg, inside aluminium sealed boxes I built inside the frame. I charge both on the bike, in the garage. I haven't balance charged in 4 months, and all cells are within .03 of each other (all cells are paralleled), and I charge to 4.15, so no cell ever goes over 4.2. Maybe I won the Lipo lottery (In addition to those packs I have built packs for friends), and I have never had a dud pack arrive, and I have never had a pack that doesn't stay within .03 (or at worst .05) of the others.

I totally respect the energy density of lipo, and I view it like petrol in that way (ie, treat it with respect). But in my experience the only time I have had Lipo problems (massively swollen packs) was from my own stupidity (massive overdischarging), and I threw those packs out immediately.

To me that is the thing about lipo, it is not idiot proof, so if the user is not sharp enough to handle it (ie observe the rules religiously), or if the user is drunk (might have been the case when I blew up those packs), then Lipo is not appropriate. Otherwise I don't get what the fuss is about.

 

[bigmoose]

The neptronix video was very interesting to me. I think we saw something "different" in it. I was expecting more charring and thermal damage to the inside/outside of the cashbox. But thinking about it afterwards, this is what I think happened. The heat we saw was the "dump" of the electrical stored energy. It vaporized and superheated the solvent in the cells. But to a large extent, the solvent didn't burn inside the cash box, because there was no oxygen ingress. Think of it like a semi sealed container, which it was. Fire needs fuel, oxidizer and ignition; the classic fire triangle. Take away one and no fire. We had fuel (solvent) and ignition (ice pick through the cell layers) but the only oxidizer was the oxygen in the box when the lid was closed. The cashbox had enough leakage to not overpressurize; but not enough to allow air into the combustion zone.... just some thoughts.

 

[dogman dan]

I think lipo should have some kind of vent, for when it does puff or vent gas. A bit of extra space may result in mostly puff, and less vented gasses. This is why I store 8 lipo's max per ammo box, I may damage all 8 in an event, but the space may help keep it a small event. Vents drilled in the box will hopefully have the gasses reach oxygen cool enough to not actually flame. I think sealed but with a vent is good

A cashbox or similar box would be likely to have enough leakage to help, but likely on a bikes battery box you have a hole for the wires to exit right? Or you can drill holes, then seal them with tape that can easily blow out.

On my bikes, it's just open top boxes. nice dry climate. I tape a baggie over the top if raining.

 

[lcyn]

I have been following this thread with interest, as I just recently got into Lipo. I love the size and weight of Lipo, but like everyone I have concerns about safety. It seems that the most important thing is to be careful with charging/discharging.
I have been doing some research on NMC.
This site has some information on batteries, (http://batteryuniversity.com/learn/article/types_of_lithium_ion) and discusses the different chemistry properties. It seems that NMC is the most stable and safe for the weight and size, but definitely more expensive than Lipo. I have seen posted on the forums that some have purchased the Chicago battery, and seem to like it OK. What about the one from Itselectric.ca? (http://us.itselectric.ca/product_p/48v-lithium-polymer-10ah.htma) (Has anyone had experience with this battery? What about the vendor? Anyone purchased from them before?

Chicago battery http://www.chicagoelectricbicycles.com/Batteries.html

Itselectric.ca http://us.itselectric.ca/product_p/48v-lithium-polymer-10ah.htm

 

[Harold in CR]

I found that video interesting, in that, when no roaring flames were present, in the first part, the bottom cell was not damaged in any way, other than probably being bad before the video was made.

That seems to me, to be a good thing, showing that the entire battery may not go up, and not be as severe a blowout, compared to a flaming fire that would cause much more damage if not confined.

 

[neptronix]

Where was the shrapnell in the video? looked like an ideal outcome to me.

A cash box is not a fully sealed enclosure, lol.

I knew the John in CR case was a hardcase lipo pack. This is why i don't like those. I had a new puffy pack delivered to me which could have suffered the same fate. But i caught it because a visual inspection made it pretty obvious.

http://neptronix.org/forumpics/lipopuff.jpg

This pack in particular, one of 28 packs i have ordered total, was very slightly puffed when i got it, and took a few weeks sitting outside to vent it's gas.

My other 2 dud packs had missing amp hours or a weird RI curve in 1 cell, and would have suffered a similar fate later down the road.

Like i've always said, there is a 10% dud rate from hobbyking with the turnigy/zippy stuff, and you really have to give everything you receive a thorough lookover if you want a safe operation.

Every pack is a death metal pyrotechnics/smoke show in the making unless proven otherwise. If otherwise, then it's a cheap, high power, low weight pack that you could stretch 600 cycles out of with proper balancing and management. The line between the two is not blurry at all to me.

 

[Ykick]

I've reworked a few bricks and the factory workmanship is pretty scary. Thin strips of insulation stuffed between tabs leaves much to be desired. Particularly, if/when a cell puffs and distorts physical cell connections further.

 

[itselectric]

I'm I being overly paranoid about a lipo fire? Below is the aluminum battery box. (Sometimes I take it off the bike and charge it inside.)

boppinbob:
If you are paranoid about leaving the lipo battery for a long time. My experience is to use air tight aluminum flame resistant box for storage. Both flame and smoke require air to burn, if you don't have air, it can't start a fire. My other simple solution is a plastic rubbermaid box and a bag of sand. The sand will create an air tight environment.

Ken

 

[amberwolf]

I've reworked a few bricks and the factory workmanship is pretty scary.

One of the otherwise brand-new 6s Turnigy with a dud cell that Mdd0127 gave me to fix up not only had a dud cell, but had a huge solder splash stuck between two of the cells inside--not up in the soldered area, but down where they are taped together.

Speculation:

That implies that the cells are typically just lying about underneath the area they are soldering them together at, so that when globs of solder fall off as they solder tabs to PCBs and such, that they can easily fall down onto cells.

It would not be surprising to find that some end up across a single cell's tabs, shorting it out and bringing it down to 0V at the pack factory itself. Perhaps the solder is vaporized first, preventing this, but perhaps sometimes it is a large enough blob to survive long enough cause the tabs to blow inside the pack, creating dead open cells that create some of the dead packs? But the pack itself still works becuase the solder blob is still shorting across it's tabs.

Then when someone receives a pack, and charges it up with a method that does not stop charge if a cell reaches 4.2V, teh entire pack gets charged to it's normal "full" voltage but since one cell is not taking any voltage (is shorted) then all other cells in the pack are now overcharged severely--worse per cell the smaller the pack. 5.6V each for a 4s pack, 5.25v each for a 5s pack, 5.04V for a 6s pack.

Or worse, if the packs are bulk-charged at the factory for any reason, like a top-off before storage, then they will sit for potentially months in this overcharged state before the user gets them.


I expect the same thing sometimes happens when they oversolder the tabs to the PCBs, where it globs down inside under the PCB, and sometimes probably shorts cells. There wouldn't be many packs that randomly happen to get hit like this, but statistically it should happen sometimes if they do indeed often have solder drip down on them in globs, or if it globs down under the PCB.

 

[dougnutz]

Just out of curiosity what do people think of the "lipo safe" bags sold by HK and a variety of other people. I recently purchased one that is large enough to contain my Lipo and small enough to fit inside the battery box. It seems to be made of Nomex and some inner lining. Possibly a fiberglass weave.

Off hand, to me at least, it obviously isn't sealed but would reduce the actual Flame travel or at least direct it, a prevent some of the heat transmission, similar to the cash box.

 

[neptronix]

Just out of curiosity what do people think of the "lipo safe" bags sold by HK and a variety of other people. I recently purchased one that is large enough to contain my Lipo and small enough to fit inside the battery box. It seems to be made of Nomex and some inner lining. Possibly a fiberglass weave.

Off hand, to me at least, it obviously isn't sealed but would reduce the actual Flame travel or at least direct it, a prevent some of the heat transmission, similar to the cash box.

Those work well for a small pack. I keep any suspect lipo in these bags before disposing of the affected cell. But they would be a nice layer of protection, and they appear to work quite well. ( the picture above was the interior of a progressive RC lp-guard bag.

 

[Ykick]

I've reworked a few bricks and the factory workmanship is pretty scary.

One of the otherwise brand-new 6s Turnigy with a dud cell that Mdd0127 gave me to fix up not only had a dud cell, but had a huge solder splash stuck between two of the cells inside--not up in the soldered area, but down where they are taped together.

Speculation:

That implies that the cells are typically just lying about underneath the area they are soldering them together at, so that when globs of solder fall off as they solder tabs to PCBs and such, that they can easily fall down onto cells.

It would not be surprising to find that some end up across a single cell's tabs, shorting it out and bringing it down to 0V at the pack factory itself. Perhaps the solder is vaporized first, preventing this, but perhaps sometimes it is a large enough blob to survive long enough cause the tabs to blow inside the pack, creating dead open cells that create some of the dead packs? But the pack itself still works becuase the solder blob is still shorting across it's tabs.

Then when someone receives a pack, and charges it up with a method that does not stop charge if a cell reaches 4.2V, teh entire pack gets charged to it's normal "full" voltage but since one cell is not taking any voltage (is shorted) then all other cells in the pack are now overcharged severely--worse per cell the smaller the pack. 5.6V each for a 4s pack, 5.25v each for a 5s pack, 5.04V for a 6s pack.

Or worse, if the packs are bulk-charged at the factory for any reason, like a top-off before storage, then they will sit for potentially months in this overcharged state before the user gets them.


I expect the same thing sometimes happens when they oversolder the tabs to the PCBs, where it globs down inside under the PCB, and sometimes probably shorts cells. There wouldn't be many packs that randomly happen to get hit like this, but statistically it should happen sometimes if they do indeed often have solder drip down on them in globs, or if it globs down under the PCB.

I've never, ever reworked a brick that wasn't suffering some problem. Hmm?

 

[kfong]

They seem to work quite well from the vids I've seen. My lipo sack looks to be made of just fiberglass weave and an outer material looking like duct tape. I'm guessing it's the fiberglass that is doing most of the work and the duct tape material keeps the air from entering. It's a one time use. I did some testing since I needed some form of fire resistant enclosure. Fiberglass burned off, Kevlar did the same which is an arimid fiber but not as fire resistant as nomex. I then read nomex is good for 700deg. The only fiber I found to handle the small hand torch was carbon fiber. I'm going this route for my Motobecane build. My other choice would of been a metal enclosure, but it would of been difficult to conform it to the shape I wanted. These packs are going to see a lot of physical abuse in the trails so I'm just going with the premise that a fire will happen. My setup is just a built to order super lipo sack.

Just out of curiosity what do people think of the "lipo safe" bags sold by HK and a variety of other people. I recently purchased one that is large enough to contain my Lipo and small enough to fit inside the battery box. It seems to be made of Nomex and some inner lining. Possibly a fiberglass weave.

Off hand, to me at least, it obviously isn't sealed but would reduce the actual Flame travel or at least direct it, a prevent some of the heat transmission, similar to the cash box.

 

[boppinbob]

That harness looks sexy. Nice box.

I think I overheard that @ the local gentleman's club once.

HAHAHAHA

 

[dogman dan]

I can recall reading about 4 whole pack lipo fires. I know there have been a few others ( like the basement event), but don't recall the details.

None took place while the pack was in storage, or sitting in between rides. Johns could have burned the whole pack, but he stored it smart.

2 were dead shorts. The pack at the races lipo, and another was a duct tape lifepo4 battery that burned down a vespa conversion. One short at the races was a operator error, the other short was a sharp metal edge that rubbed a + discharge wire.

1 was a pack overdischarged and still cycled anyway, then overdischarged, at least for a damaged pack overdischarged. That was Lyens bike.

1 was mechanical damage. I don't recall who this time, but a naked pack was bouncing around in a front basket. I don't know if it got overdischarged or not. Enough bounces could have disconnected a paralell connection?

In any case, a mistake was made each time.

Does that make lipo safe for you. Only if you are a perfect person. I sure as hell am not, I've killed half a dozen packs stupidly, but never got one hot enough to burn. Hot enough to scorch a hand though! by overdischarging.

 

[LegendLength]

Does that make lipo safe for you. Only if you are a perfect person. I sure as hell am not,

But dogman with due respect, the issue here is the fear mongering that lipo will self-destruct without any user error.

If there's anyone using lipo who doesn't realize it's dangerous they need to stop using it now. But 'danger' here means user errors that can cause fire. I'd list those as:

- rubbing (e.g. bad battery casing)
- puncturing
- overcharging
- overdischarging
- wire shorting
- puffing
- bad balancing

All of those things can be taken care of without too much hassle for the user. And the payoff is well worth it for many people, especially us e-bike users who want the lightest weight possible. 1 or 2 lbs can make a significant difference in some builds. Not everyone has the same riding style (John in cr i'm talking to you) and many of us choose this hobby because of the awesomeness of riding something light through the forest, jumping, downhill etc.. Otherwise you may as well get a motocross bike.

It's evidently true that lipo may spontaneously catch fire by itself, whether it's due to bad manufacturing or some subtle user error or just a random quantum event. But the likelyhood is **extremely** low.

That doesn't mean you should store them on top of your petrol cans in the garage. Proper steel storage is a must. But it does mean they aren't going to blow up in your hands if you tilt them to the side a few degrees.

 

[shock]

As shown in the video, put it in a steel box and be done with it. I won't even transport them in my truck for heli use unless they are in a steel box.

Even with the absolute worst condition possible (direct forceful puncture with a metal object) the steel box contains the flames just fine. Flames are what burn down houses, garages, sheds; not the smoke.

LiPo if used properly, is really the perfect battery for an ebike. Size, Weight and power density per $ cannot be touched from my research.

 

[dnmun]

to clarify, there are two different scenarios.

some pouches can short out internally and that discharges the pack into the short and the energy released is that stored in the pouch. i think that is what happened to john's pack.

the other scenario is called thermal runaway, and is caused when the cell is overcharged above the 4.2V level sufficiently to cause the crust that forms on the surface of the anode to fracture and break off, exposing fresh anode surface underneath, which then itself starts to overheat and that heat causes more of the crust on the anode to break off and expose more anode surface, increasing the thermal energy that causes more of the crust to break off.. and so on, releasing huge amounts of energy from the chemical reaction. this is the situation of thermal runaway. it happens when the pack is shorted to a larger pack with the terminals reversed, or if the charger overcharges the pack to cause one of the cells to climb way up over the 4.2V.

methods sells a HVC board to monitor the charge, and that buzzer should provide enuff warning to stop the charging before it goes into thermal runaway. if someone is monitoring the charge.

richard and gary have the new zephyr which also will shut down the charge before it can reach the critical voltage too.

i consider those to be a more useful method of preventing the thermal runaway that creates these big fires. it seems like the internal shorts like with john's pack don't release enuff energy to ignite adjacent pouches.

but i recommend people always have a shovel around to pick up any overheating or flaming pouch and carry it outside or into the bathtub. but if nothing else, douse with water until the fire is out. the water will cool the mass and reduce the intensity of the fire and maybe even suppress it enuff to stop the spread of the fire. don't hesitate, put it out first and worry about the carpet after the fire is out.

the smoke damage is bad though. i had to scrub the ceiling to get all the soot off the ceiling when i had a lipo fire from overcharging. but i saved the house. but it was only because i heard the smoke alarm going off from outside the house and could act quick enuff. otherwise, if i had not been there to hear the smoke alarms, i woulda lost the house i am sure. the flames from the bed burning were already 4' high when i entered the room. i feel lucky. second house i saved from fire caused by tenants.

 

[DasDouble]

I'm I being overly paranoid about a lipo fire? Below is the aluminum battery box. (Sometimes I take it off the bike and charge it inside.)

boppinbob:
If you are paranoid about leaving the lipo battery for a long time. My experience is to use air tight aluminum flame resistant box for storage. Both flame and smoke require air to burn, if you don't have air, it can't start a fire. My other simple solution is a plastic rubbermaid box and a bag of sand. The sand will create an air tight environment.

Ken

Haha end what happens if you open the box? "SUPRISE MOTHERFU**ER BOOOOOMM" or what? haha lolz

 

[Ellou]

Wow. Another attack of the lipo that's going to spontaneously combust. Use common sense, have a halfway decent charger and don't overdischarge. It's not hard to be safe with lipo but I agree that a little safety goes a long way.

8 yr rcer. I have took 3 cells down to 9v and drew to many amps. Besides a hot battery never an explosion or issue. I'm not saying be reckless but stop spreading fear where it's not necessary.

 

[dogman dan]

The scary part is the size of the fire, when 4 or 8, or 16 100 watt hour packs go up all at once.



In this picture, a mistake was made connecting them up. dead short. A fully charged pack that has damage can go off. I have heard of them going off when dropped. It's why I keep harping about protecting batteries with more than tape and shrink. Chafing and crushed corners are common.

I have also taken lipo packs down to 0v or very close to it by mistake, and no fire. But those were good cells. No telling what might have happened if contaminated cells went there. By 0v, they are safe btw, no energy left inside.

My scariest thing I ever had happen was a pack that arrived all puffed. That pack was puffed as hell, and charged to 3.8v. Dropping that sucker could have set it off. Glad it didn't burn down the post office, with my name still legible in the ashes.

Main thing is, I don't know of any pictures like this one of other lithium chemistries going off. I'm not saying lipo is guaranteed to burn your house down. I'm just saying don't keep them in a stupid place in your house or garage. BE careful. That's all. No different than the gas can for your mower. You don't just put gas in any old container. Follow basic rules to stay safe.

FOLLOW THE SAME COMMONSENSE RULES WITH ANY BATTERY. Protect it from damage, don't charge it sitting on a pile of newspapers, or next to the mower gas can, etc.

What sets off fear mongers here, is the usual picture of some guys first ebike. Lipo's taped all over the frame. Try to not damage them hooligan riding like that. It's the equivalent of relocating your cars gas tank to the rear bumper.

 

[Ellou]

Dogman for the most part I agree with your points. It was more directed at other people that make the one liners or make it seem like you have to have a ridiculous security system to own lipos. The same thing happened in RC when everyone started using lipos. Back then they where more dangerous and most people didnt have the basic understanding of how to care for them so the rumors of the scary lipo started. Ive been to tracks where people crash their trucks running 4s, tumble,battery fly out and besides maybe having a dirty battery it was fine. I have also crashed a few planes using lipos and besides being dented and sometimes bent nothing wrong with the lipo.(Hell no I didnt use it again.lol )

I think people choosing their words better would really help. ex. "A lipo will blow up if you leave it sitting" as oppose to "If you leave your abused lipo sitting without inspecting it for damage, then it could start a fire."
One has real information the other is just spreading fear.

To the OP. A metal can of some sort and storing your batteries at storage level should be all you need to do. I dont do the metal can but I understand why someone would want to.

Also how does anyone plug these in wrong. If your connector allows you to do that you should definitely switch to deans or xt90.

 

[999zip999]

Batteries are stored energy that can be volatile.
9 volt fire alarm battery and some steel wool ? Stored energy. Cute little 9 volt.

 

[dogman dan]

All this cautionary talk is not aimed at guys who have run RC shit for years.

It's aimed at that guy, 19, just got his DUI, not the sharpest tool in the toolbox, who just got told by somebody that the cheapest high c rate battery out there comes from hobby king. And now he's going to build his first e bike, to go 40 mph.

There he goes, at 40 mph, with Lipos taped to his $100 walmart bike frame.

 

[amberwolf]

It's the equivalent of relocating your cars gas tank to the rear bumper.

Although if cars had their gas tank on the FRONT bumper, there might be a lot less "accidents".