What happens to an ebike when it spends 2 days underwater?

strepto

1 mW
Joined
Aug 29, 2016
Messages
19
Location
Brisbane
Thought this might be of interest to the community. I have a MAC motor / 14S5P Jumbo Shark from em3ev.com converted hybrid which was sadly flooded in February, when the Brisbane river broke its banks and I wasn't home to move the bike.

After drying out I let it sit for ages. I figured it would be completely destroyed. After all, the live contacts and other parts of the ebike system had badly electrolysed. The MAC motor was full of water. The ESC had completely detached the positive terminal as well as the live wire on the main power switch.

I figured it was a write off but set about cleaning out the various bits and having a closer look.

The ESC cleaned up and after some reflowing work on the eroded solder joints everything powered up! The motor worked but started stuttering after a few days - this is when I pulled it off and opened it up and water went everywhere. Oops. Thankfully nothing had corroded badly and after cleaning and drying it out, it works fine (it needs new bearings but that was nothing new).

The battery was the part I spent the least time on initially as I figured it would be a total write off. The BMS was completely shot and a lot of the exposed metal and balance connections were badly corroded.

However, when I looked at the various voltages and re-balanced the cell groups, it held a charge pretty well!

I got in touch with em3ev and they were amazingly generous - they provided me a new BMS for shipping costs only! So, a massive shout out to them. I can also applaud the overall build quality of their battery. Bullet connectors and good quality components meant everything was easy to work with.

After resoldering a bunch of balance leads and beefing up the corroded areas around the cells things are working ok. I think it's lost about 20% capacity; two cell groups in particular are significantly down in performance.

But, overall, a win. I guess that's a testament to good quality components and not giving up on something just because it looks broken.

Thanks again em3ev for the replacement BMS!

https://photos.app.goo.gl/niagygYeAhxh1tAP7
 
Be careful using a pack with some cell groups meaningfully weaker than others. It offers new methods of failure modes which may or may not be gentle ones.
 
Heh. Yeah thanks :) I'm well familiar with lithium batteries and all their spectacular failure modes after flying racing drones for 10 years. :flame:

At least this pack is relatively self contained. However, the usual common sense of not charging unattended applies doubly now!
 
strepto said:
Heh. Yeah thanks :) I'm well familiar with lithium batteries and all their spectacular failure modes after flying racing drones for 10 years. :flame:

At least this pack is relatively self contained. However, the usual common sense of not charging unattended applies doubly now!

If you were as familiar with them as guy who tests them into various failure modes for clients all day long for a job, you definitely would have scrapped it.

Maybe you have a place to charge where if it makes that big fireball, it's not going to spread to your home and your neighbors home. It's overly reckless and negligent IMHO.

Once you have a compromised pack, it's time to recycle it. I'm of course biased because I gotta sift through house fire ashes as a job to find out root cause in forensics.
 
Fair enough. Hard to argue with that level of experience! Let's just say this battery's days are definitely numbered.

In the meantime it's well supervised on charge, and stored in a non-flammable part of the (brick-walled) garage. If it went up in a worst-case fireball there's plenty of room around it (and I know how hot these things can get).

Sounds like you have an interesting job, if a bit messy at times.
 
strepto said:
In the meantime it's well supervised on charge, and stored in a non-flammable part of the (brick-walled) garage. If it went up in a worst-case fireball there's plenty of room around it (and I know how hot these things can get).
Some things to consider:

Having seen my own house after a fire (not caused by battery or ebike stuff, but it didn't matter-still burned), I can tell you that if you don't have fireproof everything above it, and around it, the heat from it (which doesn't just radiate, it heats the air which then convects) will set whatever is at it's level or above it on fire. If the cieling is angled, then wherever the hot air accumulates it will set that on fire, or melt wiring insulation (if there is any in the hot zone) so that it shorts out and starts it's own fire.

The fire in my house didn't go on very long, just in one bedroom, but it was enough to burn a hole thru the cieling (and partway in the roof; firemen chopped the holes a lot bigger to be sure they'd put the fire out), destroy or severely damage everything in the room that was not covered by something else (even the "linoleum-like" floor covering) by melting if not actual flame, and outside that room everything above shoulder-height or so (lower in some places) that was meltable had done so or at least begun to deform, depending on how close to the cieling it was, and how close to the room with the fire in it. There are some pictures in my housefire thread here
https://www.endless-sphere.com/forums/viewtopic.php?f=1&t=49550&start=100#p733103
that show some damage, but since it doesnt' show where things were in relation to each other it probably doesn't help see how the pattern of damage occured.

The actual fire seems to have started in the asbestos mastic gluing the floor tiles down, spontaneously (they said this has happened in other houses of this era), setting the tile itself on fire, then catching the bedcoverings on fire, along with clothes nearby hanging on a chair, and then plastics, and it got so hot so fast it heated up everything else to ignition point at worst, or destruction point at best. Above a certain height in that room, there was nothing that could burn that didn't.
 
Oh wow, spontaneous combustion in *asbestos*? That sucks. I'm really sorry you had to go through that.

Sadly I know all too well about how the heat spreads around, having lost most of my stuff to a fire in my flat in my 20s (non-battery related, started in my flatmate's room so it was either electrical or a cigarette). The reflected heat from the roof is insane - I recall a ceramic electric kettle with a plastic lid completely melting - and the fire never even touched the kitchen, just the heat and smoke.
 
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