Capacitor question

[Jay Barnett]

Hiya, hoping someone with electronics expertise can help me with this question..
I have a generic EUC mainboard and i dropped a screw on the largest main capacitor which is an 80v 1000uf and it shorted and died.
Can I replace it with a 80v 1500uf ? its got basically the same characteristics, same tolerances and temperature ratings, even the same brand capacitor..
Im just wondering if the size could be critical in some way to the timing?
Seems generally ok to substitute larger caps of same voltage for many circuits, but im just wanting to make sure..

cheers in advance Jason  

[Keith]

16 minutes ago, Jay Barnett said:

Hiya, hoping someone with electronics expertise can help me with this question..
I have a generic EUC mainboard and i dropped a screw on the largest main capacitor which is an 80v 1000uf and it shorted and died.
Can I replace it with a 80v 1500uf ? its got basically the same characteristics, same tolerances and temperature ratings, even the same brand capacitor..
Im just wondering if the size could be critical in some way to the timing?
Seems generally ok to substitute larger caps of same voltage for many circuits, but im just wanting to make sure..

cheers in advance Jason  

As ever on this forum (sorry) where the electronics are concerned I can only talk from a radio control aircraft perspective, however there is good reason to assume that there are very close similarities between EUC electronics and electric flight electronics.

The large capacitors in Electronic Speed Controllers (ESC) are there to damp out large voltage spikes that get generated, these are easily of high enough voltage to blow the drive FET's, so do not run the EUC with that capacitor damaged.

As its function is as a smoothing capacitor, a higher value should not be a problem, however the spikes can have a very fast ramp up so it is deemed important that very low ESR (equivalent series resistance) devices are used: http://www.illinoiscapacitor.com/pdf/Papers/low_ESR_fact_or_fiction.pdf. If the capacitor's ESR is too high then the voltage spikes can make it past the capacitor. This may not be as critical in an EUC as the wheels are operating at lower RPM, even allowing for the higher pole count, however I cannot say that for sure.

If you do have a device with the same characteristics as the original, other than higher capacitance it should be OK.

Usual disclaimer: Please note use of "should" not "will" in the above - cannot be absolutely certain no harm will occur as don't fully know the design criteria for your particular EUC.