I recently stumbled across ES member gwhy suggesting that hall throttles be partially dis-assembled, and the bare solder connections be sealed with some type of epoxy or paint (perhaps clear nail polish), and the alternate suggestion posted was to use a non-conductive dielectric silicone grease to pack the internal parts (or do both?). Perhaps seal with nail-polish/epoxy, and then pack with silicone hardening sealant/rubber?
Small packets of silicone grease the size of your finger can be found in most automotive electrical sections at a car parts store. Silicone grease retains its viscosity from -40F to over 300F http://www.w8ji.com/dielectric_grease_v ... grease.htm
https://endless-sphere.com/forums/viewto ... 34#p904590
____________________________________________________Some throttles will sort of short out if they get too wet inside. Where the cable enters the throttle body, there is often a small plate held on with a screw that can be removed to gain access to the wire connections inside. The actual hall sensor is waterproof, but the 3 wires going into it are often exposed and can be bridged by a drop of water, causing the motor to run with the throttle at zero. If you can seal the area between the hall sensor and the 3 wires, the whole thing should be submergible. I used a little fingernail polish to soak the area. Runny epoxy would be good too.
Water gets into hub motors and causes rust, even if it is just from humidity. E-bikes in rainy and humid weather are encouraged to dis-assemble their hub-motors and coat the insides with some type of rust-proofing. An interesting side note is that in the thread about ventilating a hubmotors side-plates to let out the built up heat (to allow more amps), it was noted that when the stator gets hot, any moisture evaporates and easily leaves through the vent holes, so...it's apparently just as important to create an available exit for moisture as well as trying to keep it out?
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It is vital to keep the battery pack and its BMS dry, but I have no specific advice just yet. However...this is probably the most expensive water damage you will experience, so something really needs to be done.