What puts a bigger stress on the caps, braking or hard acceleration? My guessing would be braking, because of higher potential difference?

I too would guess braking. The stress from acceleration depends on the voltage of the battery, but in braking the voltage could potentially go higher than the battery voltage (at least compared to the battery's voltage under the load of acceleration).

Yeah, I'm thinking about higher voltage spikes from motor, and transients?

I did a little experiment with a 10,000uF cap I had, and it doesn't arc a whole heck of alot, not much more than stock Quark.

I found these on eBay, they are 1500uF, might be a little big to mount. What do you think? HERE

These ones:?
http://cgi.ebay.com/25-Nichicon-35V-...QQcmdZViewItem
They're pretty cheap!

Yeah, they aren't bad at all, but you have to buy 25 is all.

I also found THIS, they are only 10v, but they are 4700uF each, they have the 4700uF cap, three ceramic caps, and two transient supressors on a little circuit board. Seems like this would be the real ticket, you just have to use three in series, so you use 1570uF, still alot.

I found a pic of the open circuit once today, I can't find it anymore. Looks really well made. $15 though! :030:

Oh, just found a pic of it.

HERE

It looks like a great idea, but they are a bit expensive. On Friday I'll have to check what my employee price would be on those.

Seems like a neat little package. The transient supressors sound useful to shunt spikes, and there are a few high frequency caps (which look like the one that burnt on the Quark BTW).

The description supports the theory that several smaller caps are better than one single one of the same overall value because there is more surface area to dissipate the heat. Unfortunately, the cap on there looks like it's only good up to 16v. I'm sure you can find low-ESR caps on Digikey - just look for caps with very low resistance and can handle up to 105*C.

Yah, i agree with you on that one. I've noticed say... a 1000uF cap has .017mOhm impedance @100khz, and a 2200uF has only .013mOhm. So obviously more of a smaller cap is better.

I'll see what I can find on Digikey, maybe we can make a sticky thread on Quark accessories, and maintenance, and stuff?

hmmm, all I can find on Digikey is surface mount type caps, but a good selection though.

Also, what is the difference between cut-tape (CT), and Tape and Reel (TR).

I would like to find out what the voltage ratings on the ceramic caps(Novak trans-cap), and the transient chip are. Then maybe I could just mount a higher voltage cap to it?

I'm sure ESC manufacturers could integrate these chips onto their boards, you would think. For example, the Quark, they could have soldered the FET's closer to each other, and added an extra capacitor, maybe a few more ceramics too, their is room after all.

It looks like three of the trans caps in series will provide the same ripple current as three 35v 330uF caps in parallel. Plus the hf ceramic caps, and the transients are a bonus. I think I can make a nice little package of three of these soldered together nicely.

Cut tape means just what it sound like. The SMT components come packaged on a plastic tape and they just cut the tape to fill your order. On the tape and reel, you get a whole reel of the components on the tape. For smaller quantities, you'll be getting cut tape. It's what I always get. It you've never bought any sort of quantity from digikey before, just be sure to check their quantity pricing. A lot of the times, buying 250 only costs a little bit more than buying 50.

Oh, the stuff I used to buy that came on cut tape were really small resistors; 0603 through 1210. I don't know that a component, as large as a capacitor used on an esc, would come in cut tape form. Make sure that what you are getting is the physical size that you want. I don't know.

ZPB: Just remember that caps in series calculate like resistors in parallel: Total capacitance = 1 / ( 1/C1 + 1/C2 +1/C3 )
So, if you get three 330uF caps and put them in series, the total capacitance is only 110uF, but the voltage rating is the sum of the voltage ratings of all three.

AAngel: Yeah, sometimes buying in quantity can save a bunch of $$$. So, if anyone wants to get some low-ESR 220uF/330uF 35v 105*F caps, I'm in for a group buy for 10-12 of them (plus shipping of course).

oh okay, after I typed the message, I kinda figured it out. I remember when I bought some resistors as well, they came on a line of tape, in the leads.