Hi I just bought the same mosfet. Can you tell me where you bought your spdt reed switch?
Sorry about your board, glad your ok.
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Are you running it in salt water? I canāt believe that only water did so much damage. I drowned my battery once and after drying I could use it again without any problems.
I now use a pcb that I have designed with water and temperature sensors that gives an audio alarm and throttle back slowly so you know there is a problem in de electronic box.
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A friend also flooded one completely and still rode for 20 minutes with it. The battery was perfectly fine until he didnāt dry it properly and corrosion shorted kill some of the cells. Perhaps the BMS is what caused this damageā¦
That sounds reasonable, maybe some of the mosfets shorted out the battery in some way. I dryed mine with hot air blowing in the shrinkrap. Are the cells likely to corode? I tested the nickel strips in salt water / air for weeks and they do not corode at all.
Btw I do not use a bms while foiling. Only for charging so I have a balance connector on my battery packs.
The cells can corrode eventually. You could always pour corossion X through it to displace water etc as well.
Iām sure weād get @Flightjunkieās endorsement for that too haha.
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How do you keep water ingress out of your balance plugs as well ? Amphenol have the AT series but they wonāt fit easily the battery cases :
Do you use any fuse between your battery plugs like flightjunkie did ?
My battery box is 100% waterproof if I close it the right way. And I have a water sensor at the lowest part of my box so my battery will always be dry. I donāt use any fuses because I am scared of breaking my esc when the power is cutout under load. I have no problems without fuse, just be very carefull to not do stupid things. Because these batteries are dangerous so treath them with respect.
Any picture of your battery case ?
I dont have a battery case, only the waterproof box on my efoil. All electronics are in this box. The battery itself is not waterproof.
Iāve done pretty much the same thing. Made sure my board was 100% waterproof and then made sure the battery Shrink wrap runs higher up. If there is any water ingress Iāll be notified with enough time to get to shore before water gets to ESC or battery.
In my next build I will focus on all components being fully waterproofed as well though.
I agree it might be a simple and good solution but I am a bit scared to burn all my electronics if water ever gets in. Iāll make a waterproof case and make sure my hatch is watertight too but I would rather have 2 protections instead of 1. Pretty simple to burn everything with some water 
Hi.
A wet battery must be taken care of immediately. If left overnight it will be destroyed.
If battery gets wet in salt water you must remove all covering (like shrink wrap) and submerge the battery in fresh water. Wash the salt off really well, or it will slowly die from the salt corrosion over the next couple of months. Using something like āSalt Awayā to get all the salt off is also a good idea.
After getting all the salt off you must dry it quickly to minimize āflash rustā. I like to use compressed air to blow the water off. Once blown off, then dry with a paint stripper heat gun, or a high power hair dryer. Make sure the battery is completely dry. Getting the battery nice and warm while doing this helps.
Once free of moisture you must completely saturate the battery with corrosionX. Make sure it coats and soaks into everything. If you canāt submerge the battery in the CX then take your time and make sure to get it to penetrate up the insulation on all the wires, under all the nickel, and both ends of the batteries.
Let the CX soak overnight. Then wipe it off with a rag. Get off as much as you can so the battery isnāt messy but leaving some residue will help prevent corrosion.
When you build a battery you should coat everything with 4 coats of spray Conformal coating. This will help protect the battery if it gets wet, or exposed to moisture. But, even if coated with conformal coating you must still do this process if it gets wet.
Good luck.
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Hi.
Iām so sorry to see that disaster. Good thing someone was around to give you a ride back in?
Usually a wet battery continues to work to get back to shore. The damage results after the fact if not immediately de-salted, dried, and corrosion treated.
Looks like a BMS failure to me. BMSs can just randomly fail without warning while sitting in your garage overnight, or fail due to moisture / water damage.
Please be careful with these large Li-ion batteries, and even more careful if you use a BMS. I donāt use a BMS. Too risky in my opinion.
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Bruh sucks to see that.
But normally a li ion battery donāt catch fire due water. I build li ion batteries for electric skateboards. And I have seen more then one batteries with water damage.
Cells starts to corrode over time never seen something like that smoke out.
I am new here on the forum. I want to start building a efoil in some months. Unfortunately I see here on the forum many batteries without the correct safety.
Hi.
Welcome to the forum.
Do you use a BMS on your electric skateboard builds? I think the failure rate for these BMSs is higher because of the increased load. I pull 200 amps when doing tow-in surfing.
Never again will I use a BMS. I removed them from my Evolve, and Onewheel. All my DIY builds are designed with no BMS, a voltage alarm, and external balance charging.
High amp loads and high KW battery. Dangerous combination.
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Thanks!
Depends on the build. If I pull many amperes I run the BMS bypassed. So only charging is with the BMS. Discharge is directly from the battery. I always suggest to put a fuse on the output then.
But the failure off the BMS depends much on the quality that is used. How cheap the fets etc are. If a BMS turns off the power while you are going +20km/h you are going to break your vesc.
Cool to hear you have a evolve and Onewheel 
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What amperage fuse do you use? I am scared that the fuse will blow while running full throttle.
I did not use the fuse,the battery had bms and the battery itself got wet
I am building my efoil now, and i am scare that my battery burns like yours. It is my nightmare these days jaja. I guess you saved your board sinking the box right? Is difficult to put out the fire on battery with water? IĀ“d like to see your video.
Regards,
Pablo