How resilient are hub motors to wet and bumps?

[Jessiedog1234567]

I have put an 800w 48v hub motor onto a small pit bike for my son to ride around a field at the back of our house. Just a query about hub motors themselves; are they fairly resilient to the wet? I am not talking about driving through deep puddles but more about wet grass and muddy surfaces. I notice that where the cable comes out is obviously an opening, would it be a good idea to fill that with some silicone to reduce the chance of any water getting in there or would it normally be sealed in there?
Also are hub motors fairly tough when it comes to cross country riding. I am not meaning big jumps but more about uneven ground as per the field. I have seen some scooters that are suited for cross country but didn't know whether they have special tougher hub motors.
Any advice or experience would be appreciated
Thanks
Image below is of the hub motor on the pit bike.

 

[amberwolf]

Before doing anything, you might want to watch this
https://www.youtube.com/watch?v=gwlbAJLzI_w
It's got sections about water ingress, waterproofing, etc., that show how things you'd expect to work don't, and why.

There's also threads like Kingfish's "DIY Rust repair and restoration" and at least one by Doctorbass I don't recall the title of, about prepping a hubmotor for getting wet (because it's going to--you can't actually keep the water out easily).

There's also dozens of threads about waterproofing/weatherproofing the rest of the bike, wiring, controllers, connectors, etc., if you search on that type of stuff in the titles / first posts.

That said, if it's not going to be rained on, and it's not going in the puddles, it's probably going to stay dry inside.

 

[fechter]

Hub motors are generally very durable under those conditions. There isn't really much to go wrong inside one. Keeping water from entering along the wires is the main thing. Overheating is the other potential weakness.

 

[MadRhino]

A DD hub can run underwater and survive this repeatedly. I know because I did it, and the only problem that I have had was a morning that water had frozen inside. The next day it was riding as usual. Hub motors are not expansive, not enough anyway to care much about them to last many years. Yet, the big DD hubs can suffer a lot of beating and abuse, and last easily 20 to 30 thousands kilometers over 2 to 3 years without any care. Unless they are fried by overheating, they can be fixed easily. It is the simplest motorization that a bike could have.

 

[LI-ghtcycle]

+1 MR, I live in Oregon City, OR, we get almost as much rain as Seattle WA, and I have run DD hub motors (9C style mainly) and all I have ever done is use a drip loop to keep water from being directed inside the hub motor. Be careful how you seal things up, not allowing for water to evaporate out and condensate inside can be just as bad, I think it's really only the bearings inside that will eventually be a problem, I ride rain or shine for transportation to work and have done so for years, just use common sense, and don't hose down the electronics when cleaning, should be just fine.

 

[dogman dan]

The motor can run filled with water, but then rust is eventually a problem. or the water inside can freeze, locking the motor till it thaws. Is it muddy all the time, or just occasionally?

Mud is rare here in the desert, but when I get it I go wallow in it. I just drilled some tiny holes in the motor cover, so water that does get in (condensation) can get out again each time I run the motor. The vent does allow some water in if I'm riding in deep water, but no rocks or dirt bigger than a 1/8th inch hole can let in. In my climate, it won't stay wet in there long, so no need to paint the insides of the motor. in a wetter climate, you might need to do that.

 

[tanstaafl]

To avoid rust inside my bicycle frame, I followed the manufacturer's instructions and sprayed engine fogging oil on the inside of the frame. This sealed it pretty well with a relatively sticky oil that protected the surface from moisture. Is there anything like that we could all be using inside our motors to eliminate problems from occasional water infiltration?

 

[dogman dan]

You can fill the motor with oil and it will run too. Not enough to leak out the axle hole or the cover seals. It would work to just spray oil the insides, or silicone spray it, until the motor got so hot it cooks it. The permanent fix though is high temp epoxy paint on the steel inside.

 

[miro13car]

just noticed this thread
so dont complain that is old.
in cold climate where I live
you must be careful not to roll ebike from -10C cold right into say warm +20C building.
It will for sure result in condensation inside motor - such advice is just common sense, but still some riders has no imagination.
my EPLUS edives have minimum rust inside even after thousends of kilometers.
but roll it next to loading dock doors and open doors fully like for 10 minutes.

 

[MadRhino]

Hub motors are so cheap, I have no care other than performance. I always have another ready to ride anyway. I used to fry them with overheat pretty often in the early years. Today I use bigger hubs that can survive my riding style. Even with motor care and maintenance next to none, they last an amazing long mileage.

 

[John in CR]

Water ingress is why I prefer hubbies with wires coming out of the axle instead of a channel for the wires between the axle and bearing. Then starting on the axle I wrap electrical tape in one continuous piece with a lot of overlap from the axle to 2-3" of the wire harness down the drip loop. I've ridden my primary commuter in a lot of rain for the last 1.5yrs, and because it heats up pretty good due to uphill grades into the wind on the way to work, I hose it down upon arrival to keep the magnets from roasting when I park. I popped the side cover open last month when I had the motor off for a tire change, and it was still factory fresh inside despite my 17kw abuse and daily hose-down. More common hubbies have a much larger volume of air inside, which causes the motor to try to suck in more water when they cool. Keep the rubber axle seals well greased to repel water, seal as best you can, and always use a drip loop (which makes wheel removal easier too), and hubbies can be quite water resistant.

Oh, one other thing. Water follows cables like a river channel as Justin demonstrates in his presentation, so I always put the open end of the wiring harness (where the cables split to the phases at the controller) in a location where water can't get to it and point it downward so water trying to get in has to go against gravity. That's to prevent the wire harness cover from acting like a straw to suck water in when the air pressure inside the hubbie is below ambient as the motor cools.

 

[markz]

I do remember watching the entire video
Very informative!

https://www.youtube.com/watch?v=gwlbAJLzI_w

 

[miro13car]

MadRhiono,
electric drive for ebike which does not fail safe = does not protect itself from overheating is the one I would not like to ride.
so you ride in constant fear of burning motor?

 

[dustNbone]

I don't think over temp protection is a requirement for all systems, especially in the hands of someone experienced who knows their system well. I've never had thermal protection on my ebike, and I've never fried a motor. I have a pretty good idea what it's limits are, and when I'm pushing those limits.

And as MadRhino said, motors aren't that expensive. If it cooks, replace it with something more capable. Or slow down. Lol. Yeah right.

 

[miro13car]

so you are experienced as you said,
motor which is used well below it capabilities ? to use bigger motor , carrying extra weight to avoid burning it?
"within limits.."??
it is required /thermal protection/ for not experienced ebike riders who are in majority.
touching motor after climb is radiculous to me.
I have electronics built in in my EPLUS, TADIAL FORCE, BIONX , etc. drives to protect.

 

[dustNbone]

I wouldn't use a motor with integrated controller for a high performance application. It's almost never what they're designed for. Even my BBS02 which used to have an integrated controller, doesn't anymore. And as a result I can push a bunch more power through it for longer time than I could before.

 

[MadRhino]

MadRhiono,
electric drive for ebike which does not fail safe = does not protect itself from overheating is the one I would not like to ride.
so you ride in constant fear of burning motor?

No fear, no excuses. You choose for yourself, between the thrill of performance and the illusion of safety.

 

[markz]

integrated controller
performance application

That's toasty hot, not good.

You choose for yourself

Radio Controlled LiPo batteries come to mind

View attachment 1

 

[miro13car]

I ride 50km/h on my EPLUS 1000W in 20 Celsius sunny weather all day long , motor gets warm , I can hold my hand on it , nothing even close to hot.
On very hot day here in Calgary like above 30C yes thermal protection kicks in , NO thermal cut off, good design system will NOT just cut you off in the middle of road,
EPLUS limits power
even 48km/h is plenty fast for me, you call is performance or not performance - general statement.

 

[dustNbone]

I suppose it also comes down to how confident you are in your own ability to keep tabs on how hot things are.

The BBS02 is pretty easy, my left calf goes past the motor housing every pedal revolution, and if I'm running the thing hard, I give it a little dab with my leg on the way past and I know approximately how hot it's running. Controller is mounted behind the seat post, a quick reach back and I can monitor that as well.

For my application, reliability is very important. I frequently ride on mountain pass roads where traffic levels are extremely low, a total failure could be very unpleasant. I try to carry spares of everything likely to fail, basically everything but the motor itself. It's also among the reasons I run no PAS and no display. Too many failure points.

If I was going to install anything it would be a thermometer to monitor motor core temperature, maybe an alarm, but I'd never give it the ability to throttle or power down the system.

 

[MadRhino]

...you call is performance or not performance - general statement.

Simple definition: performance is a general statement that is relative to the other vehicles that are around you.

Poor performance: they can pass you.
Fair performance: you can keep up with them.
High performance: you can pass them.

Common definition: A performance vehicle is one that is competitive, standing a chance to win.