Cooling FOCBOX with heatsink!

Conscious of the importance of cooling down power electronics , I decided to measure the FOCBOX mosfet temperature using the bluetooth module and the iphone app. This post will be a comparison like for like. 2 rides 1 day apart, same set up same rider , me :slight_smile: , The heatsink was mounted using a thermal compound with 4-5W/mk of thermal conductivity to improve the contact. The heatsink is slightly greater than the FOCBOX baseplate. RESULT !!! : max temp reached 80degC without and 63degC with the heatsink , so it definitely works!!

I think I will safely raise the max current limit knowing the cooling is improved

Given how wide the FOCBOX is , this method is better than adding a fan from a thermal conduction standpoint. A fan would be useful only if a heatsink is present as the heat exchange surface is much increased.

tell me what you think :wink:


This is very interesting; thank you for sharing


This solution has crossed my mind several times. Is the heatsink exposed to the wind while riding or is it hiden in your encolsure?

It looks like there’s just a few holes drilled, but I don’t know if any holes are drilled on the other side, allowing for flow …

Thanks for this sharing mate !! I was asking myself if I really had to do this :blush: I think, you convinced me :wink: what weither and ambient temperature is it in yr country ?

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Yes part of the heatink is exposed to air, it is extending out of the enclosure. But to make it waterproof I taped it over, still we get heat transfer

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Hi Riako I rode this in Stafford :uk:, it was 0 degC these days outside. So what we measure is only temperature rise:) !!!

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Look at the pic with the compound, part of the heatsink is out

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wow :open_mouth: that is really interesting so !! I used to ride under vesc6 FOC dual 6374 130kv 12s(12Ah) But it dont exceeds 45°C (“hard ride”) / 34°C (under snow time) in a closed box. But for my esk8 I will use Fox so your report is very interesting, especially since I was thinking about to put everythingin a closed and watterproof box too … :sweat_smile:

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Having a dual setup would divide your current need by 2 therefore each speed controller would heat up much less. You have 130kv motors so they will draw even less current than mine being 149kv.

Where/how did you measure the temperature ?

I m on single motor set up. 6374 149kv 12S 5Ah

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Really guys I don’t understand how cool my vescs ( Maytech ) are going under hard riding without any cooling, with 2 6355 16/36 I never go up than 40~45 degrees. Riding a raptor 2 also around 50~55 degrees Max, and I’m a heavy rider, 110kg fully pack.:thinking:

You have to pull hard up a decent hill to get temps to come up. I have dual FOCBOX mounted on an aluminum plate.

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Ok, that perfectly make sence to me :blush: Love this topic ! Thx for the infos Im missing !! It will be a dual esk8 but only use the beautifull days (potentially hot). I got it with Ackmaniac and (around Paris, I got some VDLA on my build ) spec are 70amps motor max, 65 amps batt max on itch v6. But E1Allen seams to be dual too … maybe the not the same ambiante temperature, but almost same as your single. Surfer … wow your V4.xx stay super cool ! Air forced ? I gonna take a look at your build :wink:

Also, I’m running hard my e-dirt scooter under fox seens friday (vs. VESC 4.10 before ), its actually open air, I will put my BT module on it to see the temp (its less than 5/10°C outdoor). And then made the upgrade to see the profit !

I think its a good point and always could help our build (especially this summer).

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That was going up a steep hill on 18/36 with 107mm wheels. Was still accelerating when I backed off at 37mph but the temps were climbing quick.

Maybe 25c ambient temperature

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Hard to tell anything about it… These are two completely different runs! But at least we can say that the focbox runs cooler

Nice Research!

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Hi Death cookies , these are the same runs… , same rider / average power / speed ride time with a few diff

the point was to demonstrate if we can extract heat using this method and the answer is yes. Therefore it makes for a safer design

If I’m not wrong when you go 10s the vesc is running cooler and the motors hotter, with 12s vesc is going hotter and motors cooler, it will be nice if someone can confirm that :smirk:

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voltage will only affect your top speed, and battery current that is it. motor current is always the same regardless

but in this regard 12s will draw less battery current so the VESC will be a little cooler

You mean one VESC has a heatsink and one has not while you captured both datas?

Well, i think you have here two different runs with the same Setup but still not the same run. I can clearly see that both runs differs in Terms of Speed. Round about 6:40 you have one time a complete stop and one time not. So the difference will add up over the entire run thus making it not well analyseable.