thanks. :). I was gonna ask the same.
This is a picture of the two focboxes mounted to aluminum plate in stock prototipo DSS50+ built by lacroix.
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I ordered the pads. then realized you said you prefer a thermal tape. I think it’ll be good though afaict my focboxes are bolted to the aluminum plate.
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I like the tape because it’s cheap and you get full coverage. The pads are just as good. My preference is of zero value 
.
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No prob, whenever you can. Thanks
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Between the Focbox and the plate the best thing is thermal paste, far superior heat transfer compared to any pad or tape
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my reading tonight has led me to think that too. I think I may try that route instead.
OTOH the thermal pad that connects the FETS to the case has a much smaller area and is already limited by being a thermal pad. so I’m guessing the case to plate interface can keep up even with a much lower thermal conduction rate. hmm.
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It’s hard to say, while they are is smaller, the FETs are hotter than the case, so the rate of thermal transfer between it and the case, even through a thermal pad can be higher resistance, can be higher, and also the cooler you can keep the case, the more heat goes from the FETs to it
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Ok, before making changes and doing the thermal interface focbox->plate experimentI wanted to gather some data.
I initially planed to do this on proto#2 but it’s having it’s own issues now with a DRV fault. after previously having blown the FETS on the other focbox.
So, Let me do these tests with proto#1 (10s5p 20700b 20T/62T 155mm tire diameter )
this is my thermal test run ESCs temps shows 77 and 88. 84m climb over about 2km distance. a bit steeper at the end.
it’s interesting the two temps were that different. perhaps I should replace the internal thermal pad before doing the ESC -> aluminum plate experiment.
Hmm. that temp difference correlates with a motor and battery current difference between the two ESCs.
wonder what that is and how it would muck up my experiments. 
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so weird… swap ESCs and see if this follows the ESC…
somehow I missed this. I’m not hitting 80c on the bench.
just hitting 80c fairly easy on a hill. or carving hard.
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hmm.
Presumably swap motors first step. that’s easiest.
Then swap receiver and CAN setup next…
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So here’s a theory. what if one motor is a few KV lower than the other. my primary is 184kv vs 182kv on the secondary ( according to lambda based calculation from FOC detection of lamda) or 175kv vs 170kv (according to BLDC detection + kv command in vesc_tool )
the primary has the higher kv, the higher temp, and the descrepancy is largest when i as at 95% dutycle for a stretch at the beginning there.
blah. words. 
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VESC flux linkage measurement is about 10% under compared to oscilloscope measurement.
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@fessyfoo does that count?
Forget about the thing in front, the white box with dual side heatsinks? It was sized for bare ESCapes but not really e-board related (for a board it can be made smaller and boxier)
Eventually for a MTB with top mount 
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taking that plate out is invasive, and will be a pain. deferred a bit.
So I did a different experiment on a diff board, proto#2
Both focboxes replaced now with focbox 1.6. ( supposedly cooler on their own vs 1.7? )
Also replaced their thermal pads (fet to case) with Thermal Grizzly minus 8 thermal pads. ( 8 W/mK )
I then did my heat run
I think it did really well. never broke 80c.
the run has 3 phases of hill. often I could get close to 80c on the first phase and consistently on the second phase. With this setup on a hot day ( 34c esc temp to start) I made it all the way to the top without breaking 80c on the ESC. ( and motors got too hot. )
Not too scientific as I don’t have a good record with before data on this proto#2.
163’C motor??? 
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That’s sensor noise. 