12s focbox and reliability

Hi guys just a quick question about reliability. 12s4p 30Q, dual focbox with 5065 140kv motors running FOC sensored at 40amps 60k erpm . Worked for about 50 kilometers and then DRV error occurred… No idea why. Is 12S safe on Focboxes? Also a have quite long battery wires, should I add more caps? Is it possible that I blew my drv because of the inductance being too important?

Can be a reason yes. How long your battery wires?

could be a number of things. I personally never run anything above 10s on any 4.x hardware. (dont own F-boxes)

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Think the 60.000 erpm is top limit for the Focbox. 12s will go way over that. You need to maintain things below 60k at around 53.000 erpms to play on the safe side. That in turn allows you to use only 8s or perhaps 9s before traspassing the 60K threshold.

He run 140kV motors…you will not reach the 60k max erpm with it. Not with 12s. From 190kV you could get troubles. But there also only if you pull your trigger fully on fully charged batteries and without load. As soon as you stay on your board you will lower the max erpm.


Been running 2 focbox for over a year now, in foc, 500mm 8agw batt wires, 12s and 200kv motors (although limited to 60000 in the settings) 65 motor max and 60 battmax. Haven’t had any problems so far


He was running FOC, so no erpm limit. Also no one runs 8/9s with focbox. 10-12s is more normal and plenty do it without fail. You shouldn’t run into any issues with focbox properly setup.


There are so many factors here that can cause failure in a vesc. At those settings you should have been safe although at 40 amps per controller you are at the limit with that battery. 12s is usually safe on focboxes over any other vesc4 derivative but so many other things can weigh in. Are you unduly stressing the board out with steep hills in your area? Are your belts like guitar strings? Are the vescs secured in the enclosure safe from vibration? Are they cooled sufficiently? These are all things that have tripped me up. Without knowing the exact set up you have its almost impossible to provide an answer to the question posed. Oh and sometimes if you look at esk8 electronics with one eye half shut and the other open they will fail. every time.


Thanks guys for your inputs, I will try to add caps and report here. Also I’m really lightweight, I almost never go full power on my board, never had overtemp issues and my Focboxes are mounted using extra thick double sided foam tape… I’m the ‘’ careful ‘’ type of builder. Just wondering if 12s is usually safe on Focboxes

How many other people do not have the esc right next to the battery and added caps?

That’s all I’m saying… Lol

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Oh and 60k Erpm limit does not apply to the Focbox it’s been tested way above 100k Erpm

What do you mean by no erpm limit in foc? Does that mean It can run at any erpm even over 100k?

No Xtra caps, about 40cm of wire in between focboxes and lipos, 12s, 50A battery amps, 80 motor, dual 6374. Total weight 120 kg and I bomb up hills off-road.

I’m using true copper 10awg silicone wire though. Noticed that most cables don’t actually seem to have copper strands.

I would add static electricity also to the list. I’ve seen a lot of ppl touching their ESCs with bare hand w/o any sort of anti statics protection.


Yes, the myth about 60k erpm on focbox is a myth. Tested upto 100k or maybe even more. Posted by enertion.

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You can have plated copper strands.

Not sure. The typical stuff you buy from say Hobbyking is silver colored rather than copper. What I have now is much darker and towards brown/red/orange.

Mine is def plated or coated cause when you cut it you can see copper in the ends.

The best way to tell is simply to weigh the cable. Copper is 3 x heavier than Aluminium. In weight sensitive applications like quadcopters, you actually want Aluminium cable for higher conductivity to weight ratio.