How concerned should I (we) be about battery fires?

[interpreterdotcourt]

I was reading the article about a guy's wheel in Manhattan that caught fire while allegedly charging (or maybe not charging) and I do have concerns about how to mitigate risk in this regard. Any Li-on carries a risk of fire but these wheels have huge batteries and Li-on fires are no joke. They're like those birthday candles that re-ignite after you blow them out. I have seen a video on YT that explains that the best way to deal with a Li-on fire is to douse it with a steady stream of water (even though other videos suggest Li-on actually ignite from water but I'm sure people have opinions).

[alcatraz]

The second V8 I bought (used) had some corrosion damage in the battery. I noticed it by noting that the battery had a 15-25% less range than my other V8. I thought it was just normal wear but in fact that much is not normal when viewed in relation to that wheel's total mileage. My other V8 had twice the mileage and 20% more range. !?

When opening the battery up I noticed several cell groups had a very low voltage. They were way off. Shortly after I saw some corrosion damage. 

In any case. Had I continued to fully charge this battery I would have (continued) to overcharge certain cells over 4.2V which is a cells maximum voltage. If I also at the same time would have deep discharged the battery to lets say 1-2 bars (out of 5) I would have maybe dangerously discharged some cells below the minimum voltage (less likely, but not impossible).

So by continuing to use a battery which has had in a short time its range descreased it risks catching on fire.

There are maybe other ways for it to happen, this is one though.

Possible solutions: Open the battery up enough to measure the cell group voltages. Check that they are close to oneanother. If you have more than 0.05V difference that battery pack is rapidly deteriorating and needs to be replaced/serviced.

The cycle life is different between packs. I have a battery that's gone 9000km and it's absolutely perfect despite the winter rides at minus 20C. Another pack was crap already at 4000km.

The stories of lithium battery fires on cheap chinese balance boards were because the supplied cells were _used_ and _mismatched_ (they look like new to the untrained eye) and thus quickly go out of balance after a few charge cycles.

Edited August 23, 2019 by alcatraz

[LanghamP]

How much do you trust your Chinese supplier not to screw you over?

I feel that, having dealt with Chinese suppliers and business people, that they're all a pretty dishonest bunch, and will screw you over for a quick buck. They epitomize "if I can make a penny off you losing a dollar, then it's my moral obligation to do so."

When big big businesses like Dell, Apple, Samsung, and the rests can't stop counterfeit cells from regularly entering in their supply chain (which they have to find at great cost), then the chances of batteries, given a long enough time line, is 100%.

[interpreterdotcourt]

16 hours ago, alcatraz said:

The second V8 I bought (used) had some corrosion damage in the battery. I noticed it by noting that the battery had a 15-25% less range than my other V8. I thought it was just normal wear but in fact that much is not normal when viewed in relation to that wheel's total mileage. My other V8 had twice the mileage and 20% more range. !?

When opening the battery up I noticed several cell groups had a very low voltage. They were way off. Shortly after I saw some corrosion damage. 

In any case. Had I continued to fully charge this battery I would have (continued) to overcharge certain cells over 4.2V which is a cells maximum voltage. If I also at the same time would have deep discharged the battery to lets say 1-2 bars (out of 5) I would have maybe dangerously discharged some cells below the minimum voltage (less likely, but not impossible).

So by continuing to use a battery which has had in a short time its range descreased it risks catching on fire.

There are maybe other ways for it to happen, this is one though.

Possible solutions: Open the battery up enough to measure the cell group voltages. Check that they are close to oneanother. If you have more than 0.05V difference that battery pack is rapidly deteriorating and needs to be replaced/serviced.

The cycle life is different between packs. I have a battery that's gone 9000km and it's absolutely perfect despite the winter rides at minus 20C. Another pack was crap already at 4000km.

The stories of lithium battery fires on cheap chinese balance boards were because the supplied cells were _used_ and _mismatched_ (they look like new to the untrained eye) and thus quickly go out of balance after a few charge cycles.

Great. This is terrifying. So when I take delivery of my first wheel, a new one, I need to open it up and test the voltages? I have no clue how to open a KingSong or if I'm even supposed to. Maybe I'll have to build a cement sarcophagus to store it in while charging.

Edited August 23, 2019 by interpreterdotcourt
Wanted to add some info.

[alcatraz]

If it's a product from a reputable company you can probably wait until it's a few years old, after the warranty period. 

[meepmeepmayer]

I don't know of a single case of a battery fire where it wasn't either

• Water intrusion (on the first V10 batch due to a lack of waterproofing, which they fixed)
• Mechanical damage to the batteries from a crash or corrosion or something

Just a regular new wheel is going to be 100% fine.

After a heavy, shell-breaking crash, check that everything looks ok, and maybe don't store your wheel next to your saltwater pool/fireworks collection/in your baby crib (= do something obviously dumb). Battery packs aren't magically invincible or perfect, that's all.

No EUC pack has yet ignited without good reason.