MakerX Mini-Foc esc - Are the capacitors necessary?

I’m not very knowledgeable about how escs work so I figured I’d make a thread to ask for advice. The situation is I have an old fiik board that doesn’t run (might be a clone/ fake idk) and long story short the old esc is toasted so I thought I’d swap some vescs in there and get it running. The problem I ran into is the esc case is small. The old esc is very square and the case was built to fit it snuggly. Most dual escs which are more rectangular. So the only escs I could find that would possibly fit were two makerX minis if I stacked them one on top the other. When they showed up the first thing I noticed was a capacitor on the battery wires which wasn’t there in any pictures or videos on their site. You can see in the pictures there’s absolutely no way this will work because the esc case goes right up against the battery case and the capacitor sticks out of the esc case no matter how far you push it back. I did some searching on the forum and @rusins mentioned they used to not have capacitors so that explains why the product page has pictures without the capacitors. From what I understand escs can run without the capacitors but long battery wires and voltage spikes from braking and accelerating can cause the esc to blow. The boards battery wires aren’t very long and also it’s only a 9s LiFePO4 battery meaning I’m only at 32.4 volts (before spikes) out of the 60 volts the hardware can do. My question is do you guys think I can get away with removing the capacitors from the esc and if so how do I remove them?

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Companies don’t usually make revisions that add cost without good reason, so they might have encountered a problem in the original design that required adding the cap to resolve. I wouldn’t remove it, but you could probably cut the heat shrink and reposition the cap more favorably like horizontal to the ESC, or maybe have the whole ESC sideways and use slightly longer cables, not sure if that fits or not.


I know they wouldn’t make a change without reason I guess my idea is my setup which is the least needing of the capacitors would be able to get away with it and they would make the change so that people who are running 12s wouldn’t blow theirs. The esc won’t fit sideways. But thank you for the idea of repositioning the capacitor my only worry is just that the case is small so repositioning it might not even be enough but I’ll see.

i think you will want to keep em. maybe move the caps further away from the esc and have em inside the board if that works…?

@linsus is probably knowledgeable enough to weigh in about the necessity of capacitors in your 30V setup.

As for removing them – cut the heat-shrink open, and then you can just use some wire cutters, or if you’re fancy, a little bit of heat from a soldering iron should be enough to pull them off. Make sure to insulate the battery wires afterwards so that they don’t short!

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The caps serve to dampen quite a lot of things, including voltage spikes and drops caused by instant amp draw and switch from accelerate / brake, it absorbs eventual surges between esc and battery, it helps keep the power lines clean for your ESC to read voltage and amps.

You should keep it imho

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Would something like this be any good to add to another esc? No voltage drop sounds cool for a easy peasy lil thingy on the power wires?

Theres no such thing as no drops :slight_smile: but the caps help to sustain big current draws from the load, absorbing fluctuations in voltage both up and down. (Yes, when the mosfets turn off or you apply break, transients up is present, the motor is essensially a big inductive coil that is very volatile when exposed to switching)

Generally more cap is better but theres alot of factors in play. If you draw current long enough the energy in the caps will disipate very quick. But the transition from drawing current in caps → battery becomes alot smoother.

I remember calculating an semi ideal number for amounts of Farad on the caps and the trade off reaches its peak around 1200-2000uF or so for the Vesc6(on the electrolytes). Meaning above wont yield alot more benefit.

Drawing more current quickly => more energy => more cap needed.

Theres also alot of math surrounding ESR of the caps. Which is why a mix of lytes and ceramic is very common and often beneficial.

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Regarding OPs problem, I would not recommend removing the caps, but you could desolder them and then reposition them to fit bit better, be careful with vibrations tho, could penetrate the caps (and also wear them out alot quicker) if mounted loosely.

Alternatively buy abit smaller caps that would fit better, should only cost you 2-3 bucks


Do you have a link for some smaller caps or some insight into where to find some or what specs I should look for in my search?

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In case you havent found a solution or someone else is curious as to the answer, I have bought caps (680uF 63V) from here to great success (I think they’re genuine but I wouldnt be able to tell if wasnt anyway[Capacitance is correct and internal resistance is within margin of error so eh?]), I think you could fit 3-4x 220uF (63V rated) mounted to the top of the heatsink and connected to battery leads via 20ga silicone wire leads. Will send pictures tomorrow as I dont want to go in my cold garage right now.

while ebay is cheaper, if you want genuine unused stuff I’d recommend mouser, digikey, arrow or any of the other major distributors

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