High-power motor without capacitor

Hello forum

I purchased a Pololu High-Power Motor Driver 18v25.
I am wondering if it is possible to not use the included capacitor. If so up to how much volt and current should the board be used ?

i want to keep my design as low profile as possible and the large capacitors are just too thick.

thank you,


It really depends on your particular setup. If you have very short (and thick) power leads and keep the voltage below 12 V, you can probably safely do a couple of amps without the capacitor. However, I strongly recommend you use an oscilloscope to look at the supply voltage to verify that you can get by without the capacitor. The capacitor can have a very significant impact on board performance, and in many applications you can permanently damage the board by leaving it off. Have you considered mounting the capacitor beside the board instead of over the MOSFETs? If you do it right, you should be able to keep it lower than the surface-mount caps.

- Ben

thanks for the fast answer.
mounting the capacitor on the side is a good idea, unfortunately my main pcb board is just a bit wider than the motor driver board.

i will be using 9 volt and i am guessing the motor will draw a max of 3 A.
could i use a smaller capacitor and if so do you have any suggestions?

thank you again,

First let me apologize; when I first read your post I thought you were referring to our Simple Motor Controller 18v25, not our high-power motor drivers. For the most part, my answer still stays the same, though the bit about the “surface-mount caps” obviously doesn’t apply. Your application sounds like it will probably work without the capacitor installed, but it would be good if you could use scope to see what the power is doing when you run the motor in various ways. Generally, the bigger the cap, the better, although there are diminishing returns, so at some point you can decide that 100 uF or 330 uF or 1000 uF is good enough for your application. A smaller cap would certainly be better than no cap, and although it’s best to have the capacitor as close to the board as possible, you could consider moving it off the board by a few inches and connecting it with wires if that helps you fit everything.

Also, you might consider using our VNH2SP30 motor driver carrier, which has a very low profile and seems to function fairly well (better than our high-power motor drivers, at least) without an external capacitor.

Just to be sure, you’re not planning on using a 9V battery like this, are you?

  • Ben

- Ben

thanks again.

it will be a 9 volt power supply, not a battery.

i will check with a scope and take it from there.

the other board is too wide. i need something 1 inch wide or less.