Water cooling design for ebike controller

Ebike cooler

Ebike Cooling addict

Hi, my name is Lev Leon, I’m 28 and I’m an E-bike enthusiast.
Slowly getting attracted to the field of electric transportation, I’ve decided to quit my programming job, and take a shot with an apply for a job at one of the biggest local e-bike shops.

ebike shop
ebike shop

A few months later I’ve decided to build this bad boy, based on Porsche frame from Germany. All I’ve had before is this generic foldable 20-inch disaster:


Now I ride with style

german frame

Thoughts on Ebike water cooling system

The latest and the most important upgrade I’ve made was my passive\active water cooling mod for the controller. You will probably ask why would I do that, there’s indeed was an option to cool the controller simply mounting it outside the components box.The answer is simple – I don’t want to.

My plan was to create a powerful e-bike with the cleanest look possible, means everything has to stay in the box. At first, I didn’t think the controller will complain about the self-produced heat, but I was wrong. Have to admit, riding this way in the middle east heat for a few months, the controller deserves an applause, but the doom day had to come sooner or later.

ebike controller with mosfet cooling

It was a ride to work, I was late so I’ve taken the highway path. Going 100 km\h for about 13 minutes, 33C outside overtook the controller capabilities- it stopped, making weird noises. When the box was opened, you could easily mistake the bike for a combustion engine. The amount of heat came out of there was ridiculous, not to mention the steaks that could be made on top of the controller.

As PC gamer too, I thought to myself – why wouldn’t I make my controller water-cooled exactly as my CPU? At first, I thought I might compromise on the design levels, mounting that radiator outside, but let’s be honest – it looks friggin cool.

ebike frame
ebike frame without cooling
ebike frame with pc cooling components

I’m pretty sure the idea will spread out as soon as people will care about the build aesthetics. Personally, I’m not very satisfied with the same mounting position right on the bottom of the frame, taking all the wheel dirt and water splashes. I know, most\some of them are waterproof rated, but I’m still nervous seeing 300$ controller taking it all. If I can hide the controller at the most protected place I will do so.

Custom Ebike specs with water cooling

The water-cooling system is actually pretty simple to assemble and install and came out to be very effective ( i’d assume about 70% less heat ).
Bike specs are 72volts 45a Panasonic battery, 80a controller, Cycle Analyst, 3kw motor stuffed with ferrofluid and a hub heatsink, which probably boosts the motor to about 5k nominal. The bike has turn signals, horribly loud horn, front and back lights,two different alarms (basic alarm and GPS reports) most of it wired with relays.

ebike battery panasonic cells
Unfortunately the bike is being used as a daily commute, means I had to go for it, lacking a few tools to make it perfect, but eventually, it came out pretty clean.
The first stage was to add the water container to the controller, which I did by creating relatively flat surface right about the MOSFET heatsink screws.

I am then mixed epoxy glue with aluminum shreds, for better heat transfer. The difference between my way to attach it to using thermal paste is very small, making sure it is staying in place without any mountings was a higher priority.

radiator mounting

Mounting the radiator outside, horizontally was just an idea to make it look as the big bikes radiators, although few people though it isn’t smart to make the bike wider, I am still pretty happy with the result. The pump is 12v 3.5L/Min, powered with amp controlling knob, which allows me to use it according to the riding style.

I was suggested to replace the pump with a much smaller energy consumption one, as I am loosing too much energy, but I see barely to no difference with the pump connected to the main battery, and if there will be noticeable consumption, I have tons of used cells that can make a huge 12v battery just for it -weight is not a concern on this build.

The results of this cooling mod are amazing.

I tried to push the bike as hard as I can and the controller inside the box is barely warm (too bad I didn’t add a thermistor, but I’d say it is about 45C at the most intense use). As I already mentioned – the energy consumption is minor, but there’s always a few pumps available to match the main power capabilities. I wouldn’t say this is any type of cooling breakthroughs, and I don’t know about you guys, but if any component that I use, require hear reduction, I’ll water cooling the **** out of it.
It might be some mental disorder too.

This article was written by Lev Leon, and EvNerds published it in his name

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