Quark fried, blown capacitor...

[zeropointbug]

Oh right, you did say you did that. That's nice to know then, I was just thinking if he ever wanted a case machined?

[BrianG]

Yeah, I guess that is a reason...

zpb, I used 1/8" copper tubing that I flattened in a vice. It works really well and is available at most hobby shops/hardware stores.

[zeropointbug]

Oh yeah, I just thought of that actually. I have 1/4 inch here, but maybe I'll go tomorrow and get some, that should provide a low resistance, low inductance channel for the caps.

Hey, I just told my machinist to mill this up so I can try it out. I have emailed Mike a couple times, but he hasn't responded. He must be very busy, I won't bother him with anymore.

The distance between it is 4.00mm, I squeezed the FET's with the caliper and that is that measurement I got with a good pressure, I thought.

Yeah, I've emailed Mike a few times and never got a response. With all of the emails that he gets, I suppose that he has to prioritize his responses and what you are talking about having done is way beyond milling a motor mount. It's probably going to require a 3D machine of some sort or someone on a mill with a lot of patience.

I removed the tape off my top FET heatsink and epoxied it hanging out to one side. (the FETS are a bit off to one side so this works well) Then I epoxied it to the side of the case when I did the bottom FETS. With no end caps I get air flow inside too.
My bottom Heat pad thingy looked the same off a NEW Quark, I thought my old one came apart, but looks like they are not 'seated in' right from the start.

I just got back from racing, used smaller tires after a 15 min haul my motor was 180* in spots, my Quark was 120*, batts barely warm. I think I will try to gear up to try to equalize my temps a bit. The nitro guys really took notice this time....

My CAP mahowk is doing fine. Its quite sturdy and in a well protected spot.


As for CAP placement, I dont think it was the extra wire that was a concern. I wish I could remember more, ( I cant find it now) but it was proximity to the FETS that was a concern. (I understand electronics and wiring, but this was something that didnt make sence at the time, and I just glanced over it.)

[zeropointbug]

They probably were talking about inductance? At higher frequencies that are present in these BL controllers, inductance must be noticed and accounted for.

Also, flat wire (or flattened copper pipe), buss bar, whatever has lower inductance, and resistance than round wire. This is because inside the wire (round), there are self induced eddy currents which turn into heat.

But no doubt your setup should perform very well, i am going to have to use the same setup for a while with the clamp thing, until I get the case machined.

[plumslow]

I know on brushed ESCs you can get a cap that is too large. I had problems thermaling a G-10 until I put a cap on it and the thermaling went away. People were supposed to had problems damaging the ESC by putting too large of a cap on it. I am sure that these ESCs are very different so this may not apply.

[BrianG]

I wonder how too large a cap can cause problems?

[suicideneil]

The only thing I can think of is the spark caused when you initailly plug the batts in, or maybe if the cap stores a voltage greater than the esc is rated for, that might cause the esc to go pop? Theory being that it would be like trying to run to many volts through the esc- more than its rated for. A theory anyway......

[BrianG]

Well, the inrush current spark would be an issue if the current had to go through the ESC circuit to get from the battery to the cap, but since the caps are usually close to the battery input, that wouldn't be the case.

A cap can supply a LOT of energy and discharge very high currents, but an ESC is a high current device specifically capable of high currents.

The voltage on a cap can only be as high as the battery supplying it. It's not like a coil where you can have a reverse polarity inductive kickback many times higher than the input voltage.

Perhaps a display of ignorance, but is there a single cap solution for what we are doing here? I have six of the 35v, 330uf, low esr caps in a bank. Could I have just used one big cap? That would allow us to take advantage of the rather long leads on the cap to directly solder them to the pcb where the power leads are. I haven't seen any significant benefits to running the caps on the Quark, except that I haven't blown it up yet. The MM seemed to show great benefits, but the Quark hasn't. I'm wondering if that 1" or so of wire that I have connecting the caps is too much resistance or too long of a distance.

[suicideneil]

I think the main reason for lots of smaller caps vs one big one was that lots of smaller caps have a greater surface area to dissipate heat, and a lower internal resistance rating too- regardless of both sizes being low esr models.
It cant hurt to try one long cap though, the type with a leg coming out of each end, so you can mount it like you said. Would look much neater anyway.

[BrianG]

The leads on many caps can carry more current than the leads of a single cap. Also, more caps have a better transient response.

[plumslow]

The cap was susposed to even out and remove spikes and other types of noise that the caused the ESC to heat up. It has been 6 months since I read the stuff but check out Tekins forum they talked about this information on a couple of G-10 and G-11 forums. This may not be relevant due the the ESCs being different animals with the frequency of the brushed ESCs and using the regenerative properties. I am looking at getting into the Truggy brushless and guessing on what to order. I am not an expert but just wanted to relay information that could potentially help.