Quark fried, blown capacitor...

[zeropointbug]

Hi guys, I was driving my truck on hard pack gravel, and I thought the pack had just dumped, because the whole truck lost almost all power.

So I went to recharge and the voltage was high enough still that it would have been 1/2 pack left. So I charged it up, and went to run it, it did a proper start up chime, pulled the trottle, it cogged alot, then moved forward like super slow with almost no torque. CRAP. So I went and checked it out, there is a brown dried liquid on each end of the case that oozed out. I opened it up, and there I see the capacitor on the end, the shrink wrap on it looks like it got very hot, and it ripped and pulled away, and the capacitor vent was blown open (which is probably where the liquid came from, electrolyte).

Does anyone know if S&T will take this back and replace it? I'm going to phone them tomorrow.

[BrianG]

Ooooh, it looks like it puked its guts out. You could try calling them, but I wouldn't hold my breath since you modded it. Why not simply replace the cap? Those things are subject to quite a bit of abuse (electrically and physically), so it's not surprising really.

[zeropointbug]

jeez, how do you expect me to replace it when it's permanently in there?

I COULD maybe get rid of part of the case and put shrink wrap on it? And secure a good heatsink to it.

Anyways, if I did replace the cap(s). Do you think I should use solid capacitors? They are supposed to be alot more durable and better/low ESR performance than liquid caps.

What do you think?

[BrianG]

Thermal epoxy is easily broken. Just put the whole ESC in the freezer for about 20 min, then pry between the case and the slab. Should pop right off.

Can you get solid caps of the same voltage and capacitance as the low-ESR electrolytics in there right now? If you do replace them, see if you can get three in there instead of two. So, if there are currently two 330uF caps in there right now, get three 220uF caps. Because the capacity is smaller, they shouldn't be as big. Using more caps of the same overall rating has a better transient response and you aren't workin each one as hard.

[MetalMan]

My MGM Compro 12012 also blew a cap today - a rather large puff of smoke came out, and the truck stopped dead in its tracks.

[BrianG]

Must be the day to blow caps. Good thing I didn't take any of mine out. :026:

Hello
i suggest the capacitor don't replace back in case, esc case heat will do blow that again.
i use low-esr 105c 470uf/35v x 4P to solder power line pretty good.

I bet Quark will replace without even opening it up. You might try that first. It is rumored that they don't even look at them.

[zeropointbug]

Oh really? I will see what happens after I phone S&T, i sure hope they would replace it instead. Really, about 10 runs through the truck with a 7XL, and the thing gives up on me?! Yah right this thing can handle 300 amps for 10 seconds. :005: I don't care if anyone does open up and mod the case, they should be able to do something still, like replace/repair, w/e.

BTW, i just pugged it in again and the boot-up chime was very weak. Weaker than before.

Has anyone else replaced the caps in a Quark?

[zeropointbug]

I was just browsing around and found these... they are a new cap. The claim ultra low-ESR, and 125C rated.

What do you think? OOPS, FORGOT THE LINK!!! HERE

I am still gonna phone S&T tomorrow, to see what they can do.

[Serum]

A link would be helpful. So far it sounds good. 125C rated.. ultra low esr..

Though at 125C the lifespan of these things is much shorter.

[zeropointbug]

yah, on the product series line-up, it shows they have extended temp rating, but their lifetime is lower at about 2000 hours, the 105C's are more like 5000+. It's not like we are running these things very much though.

HERE is the product line-up page. Go down to the fourth group of series, they are low-ESR.

I'm curious as to what S&T say.. they basically told me I had to send the controller in. Wouldn't tell me anything about the blown component.. The guy on the phone kept saying "it's hard to say".. even though, I told him it was the one component between the positive batt lead, and the FETs.. grrr.

[zeropointbug]

I got a hold of S&T, they said send it in and they would replace it... that's service.

BTW, he said when I get it back, I should solder a couple good caps on the input leads for preventative maintenance. He said it should be done with large 1/10, 1/8 scale vehicles.

So I am going to find a source for these 'NICC' NRSH caps and use them. I like the looks of the 35v 330uF caps, maybe get 4 of them...?

[BrianG]

That's nice to know! You can mod it and they'll still cover it - or did you mention you epoxied the FETs to the case? If you're gonna use 4 caps, get the 220uF ones because they'll be smaller and it will be easier to get soldered as close to the ESC as possible.

Oh, just a warning, you're gonna get a bigger arc when you plug in your batteries once you do that, but I'm sure you knew that...