Quark fried, blown capacitor... - Page 7 - RC-Monster Forums

BrianG · 05.06.2007, 07:23 PM

How big are they (size and weight)? If they are as big and/or heavy as a battery pack, I would just rather get a larger pack. I realize they would help the batteries by providing a more constant load rather than being subjected to bursts, but just not sure if the gain is worth the cost in R/C (bang for the buck). However, once you get to larger 5th scale up to 1:1 vehicles, I can definitely see the benefits!

GriffinRU · 05.06.2007, 07:34 PM

Quote:

Originally Posted by BrianG

How big are they (size and weight)? If they are as big and/or heavy as a battery pack, I would just rather get a larger pack. I realize they would help the batteries by providing a more constant load rather than being subjected to bursts, but just not sure if the gain is worth the cost in R/C (bang for the buck). However, once you get to larger 5th scale up to 1:1 vehicles, I can definitely see the benefits!

The one which I use (rated ~3kW) was a little bit overkill for e-maxx.
Dimensions 216x69x38mm
Weight 566g

1/4 scale would be a blast with them

BrianG · 05.06.2007, 07:38 PM

Hmm, yeah, a little heavy/big for 8th-10th scale.

I'd be curious to see an eagletree graph with and without the caps to see how much they help the voltage stay steady, and to see if you can get the full Ah rating out of the battery since it isn't working as hard (in bursts).

Maybe a 5-10F setup would be a little better for smaller 8-10th scale vehicles, yet still provide close to the same benefits.

GriffinRU · 05.06.2007, 08:38 PM

Quote:

Originally Posted by BrianG

Hmm, yeah, a little heavy/big for 8th-10th scale.

I'd be curious to see an eagletree graph with and without the caps to see how much they help the voltage stay steady, and to see if you can get the full Ah rating out of the battery since it isn't working as hard (in bursts).

Maybe a 5-10F setup would be a little better for smaller 8-10th scale vehicles, yet still provide close to the same benefits.

Tests and simulations shows that ESR is more important then capacity, but you cannot get low enough ESR without capacity. Basically your caps ESR must be equal or less then battery's, while over discharge batteries impedance goes up so that's where you start seeing benefits, not even mentioning temp.

zeropointbug · 05.06.2007, 10:52 PM

These caps have much lower ESR than any battery available. I will be using 8 in series of the 120F cap, so 15F system with 20 volts capable. 0.0025 Ohm

It sure will be interesting. :027:

zeropointbug · 05.06.2007, 10:56 PM

Quote:

Originally Posted by BrianG

How big are they (size and weight)? If they are as big and/or heavy as a battery pack, I would just rather get a larger pack. I realize they would help the batteries by providing a more constant load rather than being subjected to bursts, but just not sure if the gain is worth the cost in R/C (bang for the buck). However, once you get to larger 5th scale up to 1:1 vehicles, I can definitely see the benefits!

Do you mean up front cost "bang for buck", or total lifetime cost?

BrianG · 05.06.2007, 11:09 PM

Both... sort of. Lipos have a lifetime no matter what. I understand they will last longer if the caps can help them run more gently, but they still will "go bad" eventually. How many more cycles will you get running with and then without the caps? I know you don't know since no one has done any kind of test like this. I can see a longer lifetime, but not sure how much longer.

Don't get me wrong, I'm not a technology nay-sayer; it's just that I don't use something for an application just because it exists. However, if it works, and has economical and performance benefits, I'm all over it.

05.06.2007, 11:35 PM

If I order these 330uf 35v low esr capacitors from ebay, is anyone else gonna want any?

BrianG · 05.06.2007, 11:47 PM

If you buy a bunch, I'll buy up to 10 off you...

05.07.2007, 12:13 AM

Brian, the deal on ebay is for 200 of them. LOL.

MetalMan · 05.07.2007, 12:16 AM

Do you know what the price per capacitor would be for us? I may be interested in getting some also.

zeropointbug · 12:24 AM

:005: 200, what a deal it is eh!

I don't know if you could ship in an envelope or not? I would not mind getting some, just for the sake of it.

If you have an eBay account, maybe you get a sticky post made for other ppl to buy these for their Quarks? as a preventative measure or course, and possibly better/smoother running. Like I said before, they told over the phone that they solder a couple extra caps on all their large 1/10 / 1/8 RC.

zeropointbug · 05.07.2007, 12:36 AM

Quote:

Originally Posted by BrianG

Both... sort of. Lipos have a lifetime no matter what. I understand they will last longer if the caps can help them run more gently, but they still will "go bad" eventually. How many more cycles will you get running with and then without the caps? I know you don't know since no one has done any kind of test like this. I can see a longer lifetime, but not sure how much longer.

Don't get me wrong, I'm not a technology nay-sayer; it's just that I don't use something for an application just because it exists. However, if it works, and has economical and performance benefits, I'm all over it.

Well, that depends on how much harder 4C average discharge (15 mins runtime) without caps (lower lows, much higher peaks) is compared to 4C average discharge with ultra-caps (low frequency current ripple/discharge, and constant discharge).

I have high hopes for this, BUT, I'm not going to promise anything yet. Until I can take a look at some eagletree recordings, and go from there... I know what kind of cycle life they have at constant rates, but what we put batts through, you just don't know. you know.

I will let everyone know how it will perform.

BrianG · 05.07.2007, 12:50 AM

The "Jea Capacitors" ebay store has a bunch of different values.

For the MM and Quark, I would get 35v caps, but the capacitance value is a different story. You probably want 3 or 4 smaller (220uF to 330uF) caps to shed heat easier. However, having a bunch of caps clustered around the ESC may be a little messy. But, if you get one, maybe two, larger ones (~1,000uF), it will be easier to mount, but harder to shed the heat.

So, now I'm not sure what value to get. Arggg.

270uF 35v
330uF 35v
390uF 35v
1000uF 35v
1500uF 35v

zeropointbug · 05.07.2007, 01:08 AM

Hey, I found that the 330uF is the best BANG for ESR/capacitance, and low ESR will mean less heat.

IMO, I would mount 2, maybe 3 extra caps, or if you want to get a little crazy, 6 of them in a bank.

BTW, I found that note in the manual about the LVC. It must have still been at the LVC I set way back when I first got it, and that's maybe why it was cutting out, because I think I set it to something like 2.5V cell, and I may very well have gone under that under a burst of current?