Waterproofing Electric Motors and Components

[cleanspeed1]

Just purchased the plans for the Mother Earth hybrid conversion, and what occured to me was how do you waterproof and weatherproof the motor and associated components so that they can be protected and stay cool?

Nothing worse than getting into a situation with high standing water, high heat, cold and other conditons. Not to mention accident protection.

[Ryland]

You can use dielectric grease on connections to keep water out, you can also use Silicone II (non reactive to copper) on connections to seal them up completely, controllers should either be weather tight and sealed at the factory or they should be inside the vehicle, but most controllers are weather tight.
Motors should have sealed bearings, if they don't then dust is going to be more of an issue then anything else.
As for water in the motor, most motors are not designed to be run in water for, but it will not hurt them as long as they have a chance to dry out at some point.
Take a look at your car alternator, it's not even close to being sealed up and if you look at it after driving in the rain you will find it soaked, some trolling motors are water cooled and the only thing you have to watch out for with them is not to use them in salt water.

[DJBecker]

Originally Posted by cleanspeed1

Just purchased the plans for the Mother Earth hybrid conversion.

Are you talking about the several decades old non-viable plans? Perhaps that's not the best place to start...


A series DC motor relies on an air cooled commutator. There is no feasible way to waterproof the brush assembly. The best approach is to have splash guards on the bottom of the engine compartment and duct cooling air from a dry location.

A good approach for power cables is a lacquer spray on exposed conductors, with a fire resistant plastic cover that allows drainage. Heat shrink can be problematic for wet locations because it wicks and traps water.

[cleanspeed1]

Thanks for the response. I know internal combustion well, this whole electric scene is new to me but I am looking forward to playing with electrons.

[DJBecker]

Originally Posted by Ryland

...Silicone II (non reactive to copper) on connections to seal them up completely, controllers should either be weather tight and sealed at the factory or they should be inside the vehicle, but most controllers are weather tight.

Motors should have sealed bearings, if they don't then dust is going to be more of an issue then anything else.

Silicone II is a inexpensive alternative to electronics-qualified RTV (room temperature vulcanizing) silicone rubber, but it will still release acid while curing.

Many controllers are air cooled and must be mounted in dry locations. That usually means a splash protected area in the engine compartment. Mounting them inside the passenger compartment is a safety problem, both because that puts traction voltage close to people and because of toxic smoke when they fail.

Motors usually have C3 shielded bearings. The bearings aren't sealed against the elements. Sealed bearings usually have low RPM and load ratings.

[cleanspeed1]

Originally Posted by DJBecker

Are you talking about the several decades old non-viable plans? Perhaps that's not the best place to start...


A series DC motor relies on an air cooled commutator. There is no feasible way to waterproof the brush assembly. The best approach is to have splash guards on the bottom of the engine compartment and duct cooling air from a dry location.

A good approach for power cables is a lacquer spray on exposed conductors, with a fire resistant plastic cover that allows drainage. Heat shrink can be problematic for wet locations because it wicks and traps water.

Sometimes you have to look back to go forward. I am getting the plans to study them, and with help update and modernize the deal.