Ride safe - a short story of ride gone bad

Here’s a pic what happened to me today:

I was only 200-300m from the beach on a nearby lake and Battery exploded :triumph:. I had to swim and push the exploding and eventually burning efoil ahead of me to the beach. I was wearing a floating west on my drysuit so this was not in any way difficult. Without the floating west the swim would have been quite a bit more demanding.
So wear your floating west always when riding your efoil!


Wow. That looks so sad.
Do you know what caused it?

Tell us a little bit about the configuration.
batteries, bms, cables, connectors, esc/vesc, cooling so we understand a little bit what was happened

How did this occur? Water intrusion? Cells got too hot? Short of some kind? I’ve gotten 18650’s wet before (and they were ruined) and never had a fire situation. Glad you made it out alive!

I saw this was your build but you never really talked about the electronics:

At the moment I believe that something caused a short circuit in the battery. Battery was 14S12P (two 14S6P parallel and both had their own BMS) from Samsung 18650 cells and the battery was in a waterproof box. My hatch was not 100% waterproof and last time I rode with efoil about an hour there was max 5mm water at the bottom of my battery and electronics compartment. Today I was in the water max 15 min before the fire.
I had Maytech 300A watercooled ESC and had a waterpump circulating water. ESC, waterpump and receiver had their own waterproof box.
Motor was Flipsky 65161 120KV and I used its own 8AWG wires. They were connected to esc with Amass AS150 7mm connectors.

Next I have to check if the motor survived. Mast and wings are ok.

Did you use a main fuse like 150 or 200amp?

I used two 70amp fuses parallel, one for each 14S6P pack.

That scary man, I’m happy that you are ok. When I see photos on this community where guys loosing their builds (which cost more 2000$ by the way) my heart bleeding.
When I have started build my e-scooter I see a lot pictures where DIY Li-* batteries burn devices, property etc. After that I have decided use LiFePo4 (even they ~30% have more weight) and dreaming when LTO and more safe batteries will be cheaper and easy available


wow! that is scary as hell! what was the bms model? was it in the same box with cells?

I don’t know the bms model. It was in the same box with the cells.

That makes 3 boards with BMS that have now burnt out. There’s a pattern developing here!
I’ve seen a fully submerged battery in both in fresh and salt water not burn out which did not have a BMS. It definitely looks like the safer option at this stage…


All these boards that catch fire that frightens me …after I may have misunderstood but to take the electrical risk when you have 5 mm of water in the hatch … why not already look for a 100% waterproofing …

There could be a pattern indeed, I have the feeling a large part comes from the balance wires shorting to somewhere, then that wire will burn because of the high currents starting the rest. This is ofc not a problem of the BMS but more of the wiring / neat working requirement that go with them.

I often suggest to put a fuse -> real or PTC on the battery / nickel side such that when there is a short along the balance wiring the fuse goes and not the complete wire.

I always highlight to buy this ultra cheap water beep sensor from Banggood or ebay. You can drive it also with 9v batt it’s super simple and warned me several times when I had water issue. Otherwise you are completely blind

Several years ago I tested some device (with transparent cover) for water leaking. I used some food coloring (I don’t know which exact - it was some expired sport supplements :rofl: ), when dry - white color, but small amount of water changed it color to bright red and stuck to place where leaking was detected.
Sure, in our scenario it will work only if you have some transparent cover of your case but it’s better then nothing while Banggood shipping your package for 2 months, like my motor…

Yep me too. From the electrical side I have no protection at the moment at all. No fuse nothing. Not even an antispark. Direct into the flier 400a! When i connect I have a spark everytime. For the waterside im on the safe side as everything is doubled waterproof. The hatch and all components are in saperate compartments. So I never had an issue with some water in the board.

No im so blown away how much was damaged here, that I will invest a lot into safety now. Fuse antispark new plugs etc.

Stay safe guys

Yikes that sucks!

Did you build the battery? Any pictures of it? Freshwater or salt water? (likely fresh because it was a lake)

I’ve been following the esk8.news battery builders club. Noticed a few things I could have done better.

Some of the key ones:
Better layout so a balance wire can’t possibly short out to an another group of cell.
Separation between cell groups so the insulation can’t rub off and short.
Fishpaper rings over the positive.
Trim the nickel strips so it isn’t pointy.

I’ve gotten water in my batteries as well, flooded it completely (fresh water). Nothing burned and it actually still was working completely wet… Had to take everything apart and dry and out and redo the shrinkwrap, but it still works well.

That’s a very good theory imo. These wires often run underneath the pack and can easily rub/get disconnected/break free and short against neighbouring cells. This was one of safety upgrade after seeing the wardy incident a couple months ago. Also, having redundancies in your waterproofing is a must! My battery pack is taped with two layers of kapton tape then I added a giant Ziploc bag over it and finally a fireproof/waterproof bag! Edit: I ran the balance wires out of one kapton layer and added electrical tape under and over it to isolate it as much as possible!

It’s also why I’m propose now a flood sensor in my receiver👍

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Yes that’s an amazing feature! Does it communicate the alert to the remote by vibrating or is it on the display?