Lipo safety

[boppinbob]

When my ebike isn't at work with me it's at home locked up on the porch. I'm going away from home for a few days this month and I want to put the bike indoors. I constructed my 72v ebike with a easily removable lipo battery pack so I can put the lipo battery box in a storage shed out back (for safety reasons) and the bike in the house while I'm away. 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.)

 

[icecube57]

That harness looks sexy. Nice box.

 

[neptronix]

You should only be paranoid about a lipo fire if you haven't fully cycle tested out your packs to weed out the duds, or abuse your lipos in other ways ( overcharge, overdischarge, discharging at too high a rate, or charging at too high a rate. )

Let me ask you something - did you read about what's required to safely use lipo before you bought it? because you should know these things already.

 

[liveforphysics]

That harness looks sexy. Nice box.

That is a damn nice harness. Nice work icecube!


Neptronix- It's possible (though unlikely) to have a failure that ends catastrophically from a cell just sitting on a table not connected to anything, as we saw in JohninCR's situation. It's also possible though unlikely to have a pack that has many good cycles with no symptoms on it just burn to the ground one day. It would require having a grain of the right containment tucked into the cell that has some coating on it to prevent it from reacting that is slowly dissolving in the solvent. It would seem almost like you would need to deliberately sabotage a cell to arrive with that sort of containment. However, it's never a bad thing to play it a bit extra safe. I've had a couple of LiPo packs just puff while sitting on the shelf unused, which means some time-delay effect containment became active enough to evolve gasses, so it's possible to have worse happen.

I agree it's unlikely if starting with good known cells, but sometimes a folks home is so important that even an "unlikely" is more risk than they wish to take, and I see nothing wrong with that.

 

[neptronix]

I gotcha.

I had one go puffy on me, but it was new and had no cycles on it, so i knew it had a defect from the start and was able to prevent it from going thermal later down the road.

Have you ever had a cycled, trusted pack go nasty on you? Have you heard of that happening to anyone else? I haven't seen any instance of that yet. There was either abuse, or using an untested pack during the first cycle in every lipo fire i've heard of.

 

[liveforphysics]

Have you ever had a cycled, trusted pack go nasty on you? Have you heard of that happening to anyone else?

Not nasty, but I did have a single cell in a pack made from 140 x 5Ah cells (25Ah 28s) just decide to puff for no reason after a few months of use. I just replaced that pack, blew up the puffed one, but in theory, if a cell just puffs randomly, it in theory could have been possible to have a contaminant that would cause the puffing gasses to ignite.

It seems really unlikely a cell would be contaminated by random bad luck with the fairly uncommon list of material contaminant that could cause this to occur, but as we saw in JohninCR's situation, such a contaminant is possible to be in a cell.


This being said, myself and hundreds of thousands of folks around the world have RC lipo packs laying all around in the trunk of there cars and in desks and workbenches etc, and the problems we've seen have almost exclusively been from packs that get abused somehow, so I agree it does seem extremely unlikely, but still nothing wrong with playing it carefully.

 

[Beachcruzer]

Since we're talking about lipo storage, here's what I've been using: 20 mm steel 'rocket box.' It's pretty rugged (I've used them to keep gear safe and dry on multi-week whitewater rafting trips) and airtight when closed. Which has been making me wonder whether it's smart to keep lipo in an airtight enclosure where it could potentially become a pressure bomb? For the record, I leave the lid unlatched.

 

[neptronix]

Gotcha Luke..

That's why i'm always pushing for a battery holding case that allows you to inspect for puffy cells. They are just firebombs waiting to go off IMHO. You seem to follow this credo a little too.

Seems to be that if a cell is going to act up, it will happen within a short period of time.

When we get to buying a house, the bike stuff is definitely gonna be in the garage.. the bike parked away X amount of feet from anything flammable.. but for now, i keep an eye out for puffies and don't have any worries. Knock on wood - no random puffies in 1.5 years of use yet.

 

[wesnewell]

I'm pretty lax when it comes to lipo safety, but if I were going to leave it unattended for more than a day, I'd put it in the fireplace I never use. Without a fireplace, I'd buy one of those old 30 gal. metal trash cans with a lid. I also would make sure to store it in a cool dry climate. A bathtub should also be pretty safe in a pinch.

 

[amberwolf]

Once I have a pack built for a bike, and it's mounted on there, it'll be in a metal box for easy carry-in if I have to leave the bike out in the summer heat. So itd be safe enough leaving on the bike. But until then:

I have my good ones in my oven (with the oven knob removed so it can't accidentally be turned on. :lol. My bad ones are in the BBQ grill outside.

The ones in the oven are separated from each other, in groups, in various metal boxes (not sealed, but pointed away from each other).


It's unlikely anything will happen, and if I'm here I could do something about it anyway. But if I am not here and something did happen, the dogs coudln't do anything to save themselves....

 

[dogman dan]

I don't worry about my lipo one bit. But I could screw up and not realize it easy enough. I could get a bad pack and have no way of knowing it immediately. So a safe place to put your lipo is worth the effort.

Like I wear my seatbelt, like I have enough insurance to bury me, etc. I do whatever is easy to lessen risk. I LOVE a good fun risk. Risk because you are apathetic or lazy is patheticly stupid.

I also store my lipo in ammo cans. But I have drilled vent holes in the back of the can. The vents then point towards the fireplace, while the cans sit on a fireplace hearth. Tape over the holes preserves waterproof more or less, but will blow out if I ever have a big event. Theoretically any flame would shoot into the fireplace. In a house or shed, the holes could point to a less flamable thing, perhaps a scrap of sheetrock, perhaps a panel for setting woodstoves on wood floors, some tile backer board a few cinderblocks. Ammo box inside a metal cabinet maybe? Just not next to the old foam mattress eh?

Since it's winter, and won't be hot in there, I am storing 75% of my lipo stash inside an old refrigerator in the yard. Perks of property ownership, I can have a junkyard. Too hot there in summer, but lots of room on the fireplace hearth in summer.

To the op, I'd say just make a fire resistant place to put the pack while you are gone in the shed. Metal cabinet or toolbox, loose stacked cinderblock enclosure, even just a little chest built from a few sticks and some sheetrock would likely be enough to contain a small fire. If it goes big of course, it won't be enough. But most likely would be just a pack gets hot and puffs some, but no fireball.

 

[shock]

I purchased this solid steel diamond plate toolbox from home depot for $40. I keep all my LiPo's in there for storage. Have no problem going on vacation and leaving them in there for a week. Whenever storing lipos' think rock or iron!

Also make sure you leave the cells around 3.7 - 3.8 volts for storage. They seem to be most stable at that voltage.

 

[Ykick]

I dunno exactly what you mean about stability but 3.7-3.8V/cell there's considerably less energy available in the event they go fireball.

 

[oldpiper]

The Hyperion charger/balancers (at least the EOS0606i, it's the only one I have) have a "store" setting which sets the batts to where they have about 60% capacity (I'm at work and don't remember the exact voltage, could well be 3.7V). The company suggests that you charge/discharge using this setting when you are not going to be using them for a week. Assuming you have the time before you go, this should give you an extra safety margin, as stated above.

Cameron

 

[Brentis]

That harness looks sexy. Nice box.

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

 

[kfong]

It’s always best to be cautious when lipo’s are used. Especially, since we are using them on ebikes. Something they were never designed for. Remember, these are foil pouches that can easily be punctured or dented. When you dent such packs you create stress points to the separators or allow air to enter if punctured. Using lipos that have hard cases would be safer, but most of us are using just the standard packs. Once you’ve experienced a lipo fire, you really start to respect the dangers they present. I’m not even sure a 44v 10ahr pack can be safely contained.

There have been 5 lipo fires that I know of in the past year related to ebikes due to various circumstances. Green machine had a fire on his wifes ebike that burned during a ride, Lyen had a similar fire, e-biker just had one recently during a ride as well. There was a fire during one of the races, one of the ebike shops had a fire in the middle of the shop floor while testing that was in one of the threads. So they do happen, and we will see more unfortunately. We aren’t even as large as the RC crowd, but some of the builds just are so poorly implemented. Stuff, you would never seen done on a production environment. I for one will be happy to move to a safer chemistry when they become available, till then I would be as cautious as possible while using them.

My friend came close to losing his house while charging packs in his basement. He is a long time RC user. We suspect the astro charger he used caused the fire. This was before he started to use balance chargers. He became so lax with using lipos that he had other packs nearby during the charge. He was upstairs at the time when the fire started. By the time he ran down stairs and entered his work room, thick black smoke was everywhere. He could barely see, he came close to calling the fire department at one point. He was able to smother the fire by going upstairs and soaking towels to throw over the packs. The fire only stops once the material is all burned off. The smoke and soot was as bad as the fire. It took him weeks to clean it up. There was burn marks reaching as high as the ceiling on the wall. If he had not been around he would have lost his house. Another local rc member lost his garage. I had a 1000ma pack go off on me while charging in a toaster oven. It practically blew the door off, so I have deep respect for these large 5000mA packs.

 

[amberwolf]

There was a fire during one of the races,

If that's SoSauty's fire, then AFAIK that happened due to accidentally plugging pos and neg together across a pack or packs.

IIRC, Lyen's fire was (probably) caused by cells that had been overdischarged at some point.

Not to dampen any of the caution or warnings, just sayin', gotta be careful what you do with batteries.

 

[neptronix]

The only RC lipo fire not caused by abuse that i've heard of was John in CR's instance, where a pack with a factory defect was charged and placed into some kind of metal case. This occurred during the first cycle. There was probably puffing as a warning sign that a defective pack was about to start a massive chain reaction fire with all the other lipos in it's metal case.. but this warning sign was not observed ( i think the lipos were just left there for a few days )

Lyen's instance was overdischarge, then charge. Classic, known way to produce a lipo fire. It would kill other types of cells without much of an event.

I'm not sure about the others. But show me one instance of a pack just totally randomly going into flames and i'll put my lipos down. So far i have not heard of this. There is always abuse or a defective pack rearing it's ugly head early on within the first cycle.

If you feel unsure about RC Lipo, don't use it. Using the least abuse-tolerant chemistry available without a BMS is not for everyone.

 

[kfong]

Yeap, most lipo fires are going to be from user mistakes, bad practice, installation, or stupidity. You can only control how you do you own build. Most won't be prepared for the awsome fire these things give off when shit happens. A brick of 6 5000mA packs is just going to scare you silly when it goes off. Best to be prepared.

 

[neptronix]

http://endless-sphere.com/forums/viewtopic.php?f=9&t=34383&p=527981#p527981

Recent lipo fire. not a lot of details on what kind of chemistry it was or anything.
Cells sat for 2 years, some at 2.7v/cell, prolly some under that, and it caught fire.

So basically this pack sat overdischarged for a long period of time. Too bad nobody advised him to stay away from this pack? too bad nobody told him what chemistry it was when selling it to them? i bet the user didn't know to test the individual voltages before charging.

You can't save everyone from their mistakes, but this one was obvious, not random by any means.

 

[LegendLength]

I've only ever heard of one spontaneous fire that was not caused by human error and that was john in cr's. And to be quite honest the posts i've seen from john are 'political' in their opposition to lipo.

 

[Haste]

I understand that not knowing feeling. What's worse is to commute to a 9-5 business job and store it in a 8 story office building... If one cell decides to go for whatever reason...


There's gotta be a fireproof storage device that could be made use on the bike, such as a front handlebar bag for some smaller 12s2p pack,That would be 100 percent fireproof..

 

[neptronix]

I understand that not knowing feeling. What's worse is to commute to a 9-5 business job and store it in a 8 story office building... If one cell decides to go for whatever reason...

There's gotta be a fireproof storage device that could be made use on the bike, such as a front handlebar bag for some smaller 12s2p pack,That would be 100 percent fireproof..

You might be able to contain the fire, but not the smoke. A single 5AH cell could fill a small room with smoke. If you fully seal the pack, you just made a flaming shrapnel grenade.

[youtube]6M5ftkN9PtY[/youtube]

 

[kudos]

Thanks for sharing that video neptronix, I'm just getting into LiPo and that has given me a very healthy respect for handling these bricks...

Kudos

 

[John in CR]

I've only ever heard of one spontaneous fire that was not caused by human error and that was john in cr's. And to be quite honest the posts i've seen from john are 'political' in their opposition to lipo.

Political? No, I'm not even opposed to lipo per se. I am opposed to the promotion of anything that isn't what it's purported to be. As far as ebike batteries go, RC Lipo is the most expensive, the least convenient, and the most dangerous. The lucky who haven't had an incident need to just get over the small battery = big cock thing that they're hooked on. More appropriate batteries have become available for lower prices, so the days of accepting the lipo risks (which are underestimated by the vast majority) because it was the only decent power batteries available to us, are over. There are only a small handful of users who need the top tier RC Lipo, but it's not what's being broadly promoted.

No doubt mine incident was rare, but I searched online and there are others. Plus experienced RC guys are still having fires that would pale in comparison to the magnitude of one with an ebike pack, so the cute little sayings like "safe in safe hands" are without merit. They're only safe in a safe place, and unfortunately that means out of the reach of most.

One cell of carnage, brand new, balanced pack, sitting undisturbed for over a month.


My RC Lipo packs now reside outside and can damage one bike at most. Other than a fireplace, the only indoor storage I find acceptable is an open fireproof container with a bag of dirt or sand suspended over it. If a pack goes thermal, the bag melts open and sand/dirt extinguish any flame and help dissipate heat. An interesting twist on that for individual packs is integrating JohnRobHolmes cinderblock approach, but orient the holes vertically. Sand/dirt dump in and maybe save a number of the packs from harm as well as reduce the incident magnitude.