Quark fried, blown capacitor...

[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.

plumslow, thanks for the info. The more the better.

As for your getting into a brushless truggy, I really can't speak highly enough of the performance of the Mamba Max on 4S lipo with a two pole motor. The Feigaos run really well, but suffer from excessive heat; but what do you want from a system that goes for less than $200. If you have the money, the MM and a Lehner 1940 8 or 9 hi amp would be a killer setup. If you want to go with a four pole motor, the Neu/Quark combo seems to be the hot item among most here.

Due to personal experiences, I'd recommend the MM/Lehner combo.

[zeropointbug]

AAngel, haven't we gone over the whole cap thing before? :005:

What a couple ppl said about too large a cap, I can't see it, maybe they just meant for plugging in sparks? The more caps/larger you use, the better.

AAngel, also I find that weird that the MM would see such a benefit for you, and not the Quark. The MM already has more 'capacitor' (3x 330uF) than the Quark, CC doesn't even recommend them for these large R/C's, S&T DOES recommend them, and from your experience the Quark doesn't really benefit from them temp wise. But maybe temp is only part of it then? Adding more caps to the Quark will definitely save the stock caps from blowing, but we don't know yet if it makes for more efficient switching with it.

I will have to see.

BTW, I just ordered a DX 2.0 for my maxx, so it will most likely be night and day for me as far as radios go...

I looked at the MM caps. Although they are 330uf, I belive that they are only rated to 25v. That may have made a difference. I wonder what would happen if you replaced the stock caps with the 35v version.

I run Spektrum in all of my vehicles. I have three of them...A DX3, DX2 and DX2.0. They do work well for me.

[zeropointbug]

Yes, but that is still more than what you use (4s Lipo typically), and having three will have a lower ESR impedance than having 2 of higher voltage.

I did a test of these caps, I reverse polarity, slowly increase voltage until I got to ~16v, then they quickly inflated and blew out.... stinky, don't try at home. :020:

I'm sure the Spektrum will work great for me, especially coming from the TQ-3.

[bdebde]

Love my Spektrum too!

[zeropointbug]

I received my Quark back yesterday, my Spektrum dx2.0 today, S&T also sent the PRO-BEC (very nice). The PRO-BEC is made by S&T and looks to be very well made, and is very small, about 1/3 the UBEC.

I attached the Quark naked board to a decent sized heatsink with the stock thermal sticky pads, and then shrink wrapped it, as well as adding two extra caps on the input bar, opposite of the stock caps. (this is temporary)

Even with a large heasink on there, and moderate driving the Quark got very hot. The heatsink got very hot and just almost as hot as the output wires, but no thermals, and the caps stayed only slightly warm to touch.

http://picasaweb.google.com/SethHuls...49267617195762
http://picasaweb.google.com/SethHuls...49267617195746
http://picasaweb.google.com/SethHuls...49271912163074
http://picasaweb.google.com/SethHuls...49271912163090

AAngel: With my Spektrum radio now, I don't have the low speed capability I had with the stock TQ-3 radio, it's definitely not a snails crawl anymore, which I miss... but no more glitching!

[jhautz]

Originally Posted by zeropointbug

I received my Quark back yesterday, my Spektrum dx2.0 today, S&T also sent the PRO-BEC (very nice). The PRO-BEC is made by S&T and looks to be very well made, and is very small, about 1/3 the UBEC.

I attached the Quark naked board to a decent sized heatsink with the stock thermal sticky pads, and then shrink wrapped it, as well as adding two extra caps on the input bar, opposite of the stock caps. (this is temporary)

Even with a large heasink on there, and moderate driving the Quark got very hot. The heatsink got very hot and just almost as hot as the output wires, but no thermals, and the caps stayed only slightly warm to touch.

http://picasaweb.google.com/SethHuls...49267617195762
http://picasaweb.google.com/SethHuls...49267617195746
http://picasaweb.google.com/SethHuls...49271912163074
http://picasaweb.google.com/SethHuls...49271912163090

AAngel: With my Spektrum radio now, I don't have the low speed capability I had with the stock TQ-3 radio, it's definitely not a snails crawl anymore, which I miss... but no more glitching!

Looks good ZPB. How hot is hot? Did you temp it?

One thing though, it looks like the shrink is all the way around the heatsink. You might want to allow some better air flow over the heat sink fins so it can get rid of the heat.

[Serum]

Seth; have you got more pics of that BEC?

surprising that the controller still gets that hot. Good thing the thermal shutdowns are history.