Dogman Dans E bike burns his house.

[amberwolf]

FWIW, the most common problem (based on threads here on ES) with integrated-BMS ebike packs where the BMS has caused the pack failure is that the cheapest possible BMSs are used, not only in manufacturing, but also in design. So there are no safeguards against certain kinds of cell / wiring failures (the BMS simply can't tell something is wrong), and no protection against failed BMS components damaging cells thru group discharge via balancers stuck on / etc., or thru letting the cells overcharge or overdischarge.

If good-quality, well-designed BMSs were always used, it would be much less of a problem. (though since many of the packs using cheap BMSs also use cheap cells (sometimes even recycled garbage), the pack would still fail--just not because of the BMS).

 

[dogman dan]

As far as it being likely your battery burns your house down, its not. Even with lipo charged in the basement, its not. Its still odds like winning big on the lotto that it happens to you. Even the notoriously bad hoverboards never actually burned very many houses down. I got lucky.

What the problem is, is if you get as lucky as I did, and hit the lotto odds of your house on fire while you sleep, the result is pretty traumatic, if not deadly to you, your pets, or god forbid the kids in the next apartment.

The chances of it are not why I suggest people start keeping those batteries outside, or at the very least, do all charging outside. The problem is if you are the guy who gets real disaster, its just pure hell.

I just recently had my last battery die off the usual way, the way that's typical. Out of the blue, it just went from working fine, to having half capacity. Pretty clear one cell died in a cell group, It charges full, then almost immediately drops to about 4 v low. One cell group has a short, and it just trickled down till all the cells died in that group. No drama, no fire, no way a bms would have helped. The pack is sealed, potted in resin, so no way to turn it into a functional 13s pack. But had this one gone up in flames, it would have taken off slower, having to burn through all that resin. And it would have been doing that in the backyard anyway.

It was just unbelievable how quick the cheapo 18650 pack went off during the fire. It sounded like a big string of firecrackers in the garage as I was jumping out of bed and pulling on pants.

 

[amberwolf]

Pretty clear one cell died in a cell group, It charges full, then almost immediately drops to about 4 v low. One cell group has a short, and it just trickled down till all the cells died in that group. No drama, no fire, no way a bms would have helped.

A failed BMS will cause this same problem, if a balancer fails shorted / stuck on. How much current that circuit handles determines how quickly it will drain a group, and also how much less charge that group will ever get vs the others (since some of the current is bypassed around the group during charge under those conditions, vs the others, that group will never finish charging).

 

[dogman dan]

Yeah, short could be in the bms. Anything that could short one cell group with a tiny trickle could be the culprit that just killed my Luna pack. A short from a discharger stuck on could be more common than the bms letting the pack overcharge till it catches fire, or a single cell developing internal short. FWIW, I stored that pack hot, outside in the summer. It lasted two summers and died in the fall this year.



You can only guess what really started a battery fire when nothing is left but a hand full of empty burnt cans from two batteries with hundreds of cells each. The fire department investigator just called it charger malfunction when my battery burned the house. Both packs were on the bike, one was charging, the other had just charged.

 

[2old]

Luna continuously extols the virtues of their "wolf" or whatever they call it pack. Seems like it's more of a "lamb".

 

[dogman dan]

The wolf pack was an outstanding pack while it lasted. It performed beautifully under harsh discharges use. Since they sent it to me free, I went ahead and hammered it hard with a big motor and 30 to 40 amps discharge rates. So I'm not all that surprised it lasted two summers, and not four. Its lack of sag under load amazed me. But I was riding it hard for sure.

I really liked that it was fully potted, a couple times I charged it while it rained, using a satiator. That was just amazing to me. I also rode in some pretty good rain too, in the mountains.

But it may have just been the same old bms failed thing that killed it, or I killed a cell with those discharges. I still call it a good battery. But it just shows that even a great battery can be used up early, if you run it hard enough.

In any case, the Luna pack did not burn my house, get hot, or even try to burn the house down. It just dropped 4 v, and now only holds about half capacity.

 

[RTLSHIP]

Dogman, can this happen with lifepo4? I'm assuming it's unlikely. I should charge unattended in patio away from anything that could accelerate or fuel fire. Hope you are feeling better. I had a charger smoke up once. It happened in red charging mode not green.

 

[neptronix]

Battery PTSD is real. I once smelled some incense that smelled like burning Lipo in my lady's house and freaked out looking for the fire. I still cringe when hooking up batteries.

My hopes of converting a sports car to electric power are waiting on solid state batteries with better safety. I also have a battery protection device i call the 'battery bong' i'd like to develop for use with ebike batteries in the interim.

 

[amberwolf]

Dogman, can this happen with lifepo4? I'm assuming it's unlikely. I should charge unattended in patio away from anything that could accelerate or fuel fire.

It's unlikely but batteries hold a lot of energy in a small space, and if something does go wrong, it usually happens very quickly and can be very difficult to bring under control or stop.

I don't really trust any batteries, and in general have all of my lithium rechargeable devices not in the house, whenever I'm not using them. There are exceptions like my laptop that because of mechanical connection issues can't be moved around, so it has to stay on the "desk" in the bedroom, and any devices my brother has in his room (because he's there all the time anyway so if something does go wrong at least he will know about it immediately). My housefire wasn't battery related, but I don't want another one that is. :/ I still flashback to that time whenever I smell certain things, especially plasticky-burning types of smells.

 

[wineboyrider]

I leave my greenworks 40v batteries everywhere and my ryobi too. Only battery that caught fire on me was HK lipo.