andsetinn

If it isn't mentioned it should be legal, unless you're running the old Trinity spec rules which stated that unless something was specifically allowed it was forbidden.

tornado

Yeah ...it is legal..unless it is filled with NOX

Bryan

GundamWZero

iTrader: (4)

Nah, I am not looking for zip, already got that! It doesn't have the long running stamina that it once had when I was running the 4700uf cap. I went to the electronics sites to buy one and I got lost again...... I would normally waltz into a Radio Shack, plop this capacitor on the counter and WHAMO!!!! get a new cap for pennies on a dollar........... But here in Germany, its another story.......


Anyone got a couple of 4700 uf, 10v caps they can mail to me?


pretty please?

gcooper

Hi TImXLB,

Thanks for the info. How has it been working for you have you noticed a big difference before and after?

Coop

POOKYT

OK fellas I read the entire post and the extras. I need a simple answer to a pretty simple question about the capacitors.

I have a Quantum Comp. I have purchased the worlds kit and now I want to install it on the speedo.

Questions:

1 In stock sedan racing do I use the large or the small cap?

2 In 19t sedan racing do I use the large or small cap?

3 In 7-10 turn mod sedan racing do I use the large or small cap?

I understand by using the caps I may experience harder wear on my comms.
Thanks guys

Brant

donoman

OK check this out, for the non-technical people a great analogy for a capacitor would be a water bottle.

When your battery is at full voltage 7.2V or higher, your capacitor (water bottle) is going to fill up with water (electrons). The higher the capacitance, the more charge this puppy will hold. The voltage rating on the caps is like how thick your water bottle is. If it was made with very delicate material (rice paper) then it couldn't hold much water, could it? So, the higher voltage rating means a "stronger" capacitor.

Now your water bottle is full and you're trying to pour more water in. It simply can't get in there once it's full of water, right? The battery no longer charges the capacitor at this point.

If there is an event where the battery drops voltage quickly (you burst on the throttle or you get some noise or something) the capacitor will dump its charge to compensate. This is why we put it across the battery leads. Think of it as a backup battery (actually, it is) that is just helping your battery out.

When your capacitor dumps that charge (water), it needs to exit the capacitor. Think of low ESR as low resistance, a BIG opening on your water bottle. Think of High ESR as a small opening, a tiny pinhole. The low ESR (Big opening) will allow the dump to occur quicker, right? And less heat will build up too.

Now, I'm not sure what the power capacitor actually does in regards to "Boost" but I believe it COULD help in 2 ways:

1) Keeps the battery voltage looking higher to the ESC preventing heat buildup.
2) Maybe the battery becomes highly resistive at low voltages, in which case you would notice the dump of electrons from the capacitor.

Make sure you always have your capacitors in the correct direction (+/-) otherwise you will screw things up. You might even start a fire if you hook it up backwards and cause a short between your battery leads.

My guess is that the capacitor allows for a quicker dump when you suddenly change throttle positions and therefore people "think" they are getting better midrange power.

But, do the calculations, even if the Cap is supplying only 10A , and it's a huge 10,000uF cap, this won't be able to last longer than 0.01s. Which is enough to help boost the motor for the initial throttle change and help with throttle response, but not enough to make you feel like you are squeezing a NOS bottle the whole way down a straight.

Um, just a semi-uneducated view on things

donoman

Since we're on the topic of electronics, do all the ESC's use EMF braking? I designed an H-bridge that used reverse torque on the wheels for an robotics competition (homemade software-based ESC) and boy, we kicked some serious butts at the national competition against the guys with simple regenerative braking. In fact, we took the cookie due to this technical advantage.

LeadFoot

I'm not sure if anyone mentioned that there is a price to filling up a capacitor. That part does not happen for free. A bigger cap will require more draw from the battery and more caps will need even more draw to fill up the cap.

Not a big deal when you are at the start of the race with a newly charged battery but more of an issue towards the end depending on the type of course you are racing on.

Remember, everytime it discharges, it must be filled up again. The bigger the cap the more that it will need.

So, there is a give and take effect and a point of diminishing returns.

That is not to say they do not work, just that there are limits


POOKYT:

Small one for Stock: There are fewer spikes because the motors draw less and 3300s can handle the load.

Large one for 19t and mod: Larger current draw more spikes in power.

More important for technical tracks where you are on/off throttle more often than flowing long tracks where you can go the whole race without going off throttle.

LeadFoot

donoman: Can you explain "H-bridge"? Because for brushless this might be interesting because those motors and esc have very little brake

TimXLB

iTrader: (14)

gcooper:

Hi,

I ran the double cap/double hyper booster on the Binary stock motors we ran at Cleveland. we noticed more punch when compared to running just one cap and no Hyper boosters. I haven't this setup on too many other stockers ( the M/S was the only other motor). as for run time after installing both caps/hyper boosters we lost around 10 to 20 seconds at 30 amps. still had plenty of time (around 90 seconds) at 30 amps on our T35.

sorry for not responding earlier but I haven't been online much this week.

Thanks

POOKYT

Thank you Leadfoot! The only other question I have now is can I run a small cap with my tekin G-10 since it is in the car I race in the stock class. OR do I even needone with the Tekin?

Thanks Fellas

Brant

donoman

Hi Leadfoot,

H-bridge is basically what ESC's already have to run in reverse. However, I'm not sure if any ESC's use their H-bridges to brake faster.

Before we tuned our robot it would spin the wheels in reverse when braking. Once we got it right, without slipping the wheels, the reverse torque was very powerful.

DOMOisCOOL

I bought a 35v 1,000uF capacitor from RadioShack. I thought the voltage was too high, but I bought it and will give it a try. Will this capacitor harm my electronics since it has 35v?

donoman

Andrew, read my previous post regarding capacitors. You will understand the voltage rating.

TryHard

iTrader: (4)

Hey Guys, I just read through this thread.

I recently brought an MRT VX pro Speedo, and it cam supplied with a Power cap to it, however when soldering it together, I somehow managed to get confused and soldered it back to front, que a craked top to the cap, and liquid spaying out.....
(FWIW the cap I blew says on it that its a Rubycon 16v, 1500uf ZL, T0308, 105degC, if that means anything to anyone)


So I'm looking for a new cap, and I've had a look over some of the specs you guys have said, and have had a little hunt.
What I want to know is are these any good.
Maplin Capacitors
the ones I was looking at are down the bottom (mainly 4700 and 10000 uf ones).
I can't see any figure for ESR though, but maybe I'm being blind, but then again I find electronics extremely difficult to understand (thanks to donoman for the "english" explanation)

If these are any good I'll pop it a Maplin store and pick one up, maybe more, cause at 40p for a 4700uf, 16v one thats super cheap .

Regards
Ed