Adding Capacitors, what voltage and how much is too much? - RC Groups
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Jul 12, 2012, 05:47 AM
Its not that windy...

Adding Capacitors, what voltage and how much is too much?

Hey all,

I've recently bought the 150A 6s ESC from HK. I'm not actually planning to use it in an rc car, but that's besides the point of this post. Bottom line is that I need to reduce the voltage spikes as much as possible.

I've been reading up on the topic of adding caps to escs. Every time someone adds capacitors, they seem to use ones that are nearly twice the input voltage.

The HK esc only uses 25V caps, good brand caps, but only 25 nonetheless.

My questions are:

Shouldn't I upgrade the caps to 50V versions?
And as long as I'm at it, how big of a capacity can I add?

Thanks for any and all help!
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Jul 12, 2012, 08:34 AM
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wparsons's Avatar
You can add pretty much as much as you want within reason (ie not adding 5000mah of capacitors). If you add too much you can damage the batteries when they try to charge up the capacitors when you first plug the battery in.

There's no benefit to running a higher voltage, unless you can't find the lower voltage ones easily.
Jul 12, 2012, 11:03 AM
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traxx de maxx's Avatar
I think when adding caps to anything you need to go up atleast 30% more Volts than the system.
I think it's 30% but i could be wrong.
Jul 12, 2012, 05:46 PM
Registered User
wparsons's Avatar
You don't *NEED* to add buffer in the voltage, as long as the caps are rated for the maximum voltage you'll ever run.

I would go with a bit more than 25v if you plan to run 6s since 6s fully charged is 25.2v.
Jul 13, 2012, 06:22 PM
Its not that windy...
I ended up buying 50v caps in case of voltage spikes. Don't mean to ignore your advice wparsons, but if larger won't hurt, then I might as well use bigger ones.

Thanks for everything!
Jul 15, 2012, 05:56 PM
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wparsons's Avatar
^^ Like I said, there's absolutely no harm in having higher voltage ones. You won't see any benefit if your voltage is well below the limit of both, but if you're running right near the limit it'll be nice to have the extra head room just in case.
Jul 16, 2012, 01:03 PM
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traxx de maxx's Avatar
do they not store the same amount of voltage that supplies them anyway.
so if you use it on a 20V system then only 20V will be stored no matter how high the voltage rating is on the cap, or am i wrong somewhere.
Jul 16, 2012, 09:48 PM
Registered User
wparsons's Avatar
No, you're 100% right. They only store the voltage being supplied, the voltage rating is just the amount of voltage they can happily store.

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