Quark fried, blown capacitor...
 

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.

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.

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?

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.

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.

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.

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?

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.

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.

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.

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...?

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...

no comment.....

Yeah, that might be a problem, you don't want to go too big because of arcing like you said, your plugs might just become vapor after a while. :005:

Other option, what do you think about making a plug literally soldered right onto the board and poke out of the case? And have a cap bank on the battery end of things, right next to the deans, so almost no wire length between the caps and the case. But do you think caps should be on the other side of a plug?

BTW, i've tried to find solid polymer caps, but only made up to 16v. The only place I have seen them is a PC motherboards, video cards, some new sound cards. I don't want to run them in series either, IMO.

I wonder if ultra caps would help. Do you remember our thread back in Dec.? They would simply be for more power and take load off batts, but if used right, could they function as a power stage cap?

One way to help with the arc is to use a light bulb between the last contact you make. Once the caps equalize, no more arc.

I'd keep the wire coming out of the ESC. If anything, use larger 10GA wire.

Yeah, putting caps in series will add their voltages, but halve the capacitance (assuming you are using two of the same values). Ultracaps might help, but are too big and heavy IMO. Not enough bang for the buck weight-wise. You have to keep the caps as close to the ESC as possible.

I would just add the caps to the PCB or the wires right before the ESC.

If you decide to get some caps, you usually can get a better price if you buy bulk. I would be interested in ten 220uf 35v caps. If we can get more people on this, it can be a group buy...

ICIC

Where are you thinking we can get these caps? I can't remember what caps Quark uses, but I don't think they are the best, IMO. They should use three at least too.

What size are the ones in the Quark? 350uF? I can't remember.

Do you think it would be worth it doing a group buy, i'm just thinking of the shipping cost too... you know?

I wouldn't mind buying a whole lot of these either, like 50 or so, just to have for what ever. Low-ESR caps are fun when playing with pulse discharge.... brass washers.... wire coils.....:005: :005: Sounds like a gun shot when you short the coil out on a bank, and many disappearing coils. lol i was using 300 volts though.

Guys like you are the reason why the guarantee rules get tighter and tighter.. No need to explain this, i think?

You 'modified' it, you need to tell them honest what you did to it. as simple as that.

Couple days ago I just bought 10 of the 220uf 35v caps that Brian recommended. The price was pretty cheap from Digi Key, only about 3-4 dollars for 10. The shipping and handling was was probably 2 times that though.

Let us know how you used them and how they work. Pics are required of course. :)

Anyone got a recomendation for caps to use across the battery leads? Id like to do this mod. I feel like I push my Quarks pretty hard and anything I can do to help them I am interested in doing. Unfortunatley i'm kind of an electronincs dummy. I know capacitors basically just store a charge and release it when the overall system voltages drop to keep the votages as even as possible. How does adding more capacitiors help? Make it more resistant to voltage drop therfore drawing less amps by keeping the voltages higher?

Did S&T recomend a capacitior to use? A link to a place to purchase and any instalation instructions would be great.

Yes, adding caps will help supply a little extra current boost when the ESC pulls heavy current in bursts, but the capacitance value of those don't really provide much help there. They are there to help absorb the back-emf pulses, since they are really A/C pulses. So, they are used as storage to a small degree, but more like A/C filtering. Maybe GriffinRU can provide a little more insight since he seems to have more experience with ESC design.

They are not really for voltage drop, they are for power conditioning and noise/spikes absorption. They take a crap load of abuse, obviously, and more of them spreads the load between each of them. They also provide more of a pulse when switching.

We should figure a good value for the capacity and use that, too much capacity, to much arcing will occur when plugging in batts.

About 'no comment', all I said was the cap had blown, I looked in, saw it... I mentioned I had a plate adhered to the case. He just kept telling me to send it in and they would replace it, he obviously didn't care, then he was talking to some guy in Switzerland? Who could that be? :005:

But yah, I'm thinking either 4 220, or 330uF caps right in next to the Quark input. I'll let you know what I decide

IIRC, the Quark has two 330uF 35v caps. Adding 2 more 330uF caps would bring the total capacitance up to 1320uF. Better yet, use three 220uF caps - same overall value but should handle the current better and the increased overall surface area will help with heat. It might be difficult to add three more caps close to the input and still have short leads and not look like crap. Two should be fairly easy though.

yah, 2 330's sound pretty good. Also, what do you think if one made a little cap bank of say 4-6 caps of 330 and made another input in the case right next to the batt input, and had the bank protected by shrink wrap? It would sit right up to the Quark, either they lay down on side, or 4 standing up in a square bank, do you know what I mean?

what does IIRC mean?

Yeah, a little "bank" should work ok. Just keep in mind that the more capacitance you add the more arcing on battery hookup.

IIRC=If I Remember Correctly. :)

Oh sorry didn't reply to you. The capacitor they recommend, sort of (easily available somewhat) is the Novak power capacitors. Just so they can say hey, here, this is the one we use, they work.... know what I mean.

Here is a LINK

They look good to me, should work great for the Quark, having 2 680uF caps.

Forget that, that is the wrong capacitor for this, it's only 16v caps. They just mentioned Novak caps, so I searched it. But I can't seem to find 35v Novak ones, they seem to only have 25v caps, I don't think thats enough IMO.

I'll find something.

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?