RC-Monster Forums - capacitor specs

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- - capacitor specs (https://www.rc-monster.com/forum/showthread.php?t=7696)

Not good, thanks---I'll forward your comments to Engineering.

Quote:

Originally Posted by BrianG (Post 117824)

BTW: NovakTwo, there is an error on this page: http://www.shopatron.com/product/par....56.7400.0.0.0

The title says 680mF, but the cap is actually 680uF. Just a factor of 1,000 different. :smile: Not a big deal, but someone might make an issue of it...

So many questions, so little time ( I have no technical knowledge).....

Quote:

Originally Posted by BrianG (Post 117809)

Ah, the trans cap contains voltage clamping transorbs. How much energy can the circuit safely shunt before heating up too much? Can you release specs on the transorb devices (or at least the device part number so I can look it up)? I wonder how it would perform if one were to upgrade the cap from the stock 10v 5600uF to something in the range of 35v ~1000uF (trying the keep the physical size close to the same).

Also, the cap is only rated for 10v, which limits the battery voltage to 2s or 7 cells max. Too bad there wasn't a higher voltage version, something in the 25v range for people with 3s to 5s systems.

Adnan answers:

We use two 12 volt Trans sorbs and they are rated at 1500 Watt each (SMCJ12A). Replacing the capacitor we use (for our BL controllers) is not a good idea as we use 30 volt MOSFETS for the lowest possible RDS rating and we design with a safety margin of 2 to 1 with respect to voltage break down rating.

This is done to protect the MOSFETS from voltage spike damage especially during hard braking. The capacitor we use (5600uF) is very low ESR and high ripple current capable device that prevent high voltage spikes under heavy load conditions.

Thanks for finding that data for me. :smile:

I understand (and appreciate) overengineering the FETs, but I was actually referring to replacing the cap on that transorb module to allow use on other ESCs. But, now I see that the transorbs would have to be replaced as well for higher V versions. Might as well build a module from scratch...

Just want to take a minute to say thanks for answering the various questions, especially considering they're on the CC subforum.

My MMM caps are also dented, but I can't find 330uF caps.
Can I use lager uF caps? Thanks.

Yes you can, but the voltage still needs to be at least 25v and must be low-ESR type. Whatever you find will likely be physically larger and harder to mount cleanly.