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Old 07-27-2004, 03:28 AM   #121
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Originally posted by 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?
Higher capacitor voltage rating will not harm your electronics.
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Old 07-27-2004, 06:39 PM   #122
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donoman: awesome explanation! it helped me get a much better vision of what a capacitor does, i think it's worth a try, my esc doesn't come with any capacitors (novak dually) btw it works great with a 10T, on the stock profile it gives you a very linear acceleration.
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Old 09-12-2004, 03:41 PM   #123
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Quote:
Originally posted by 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?
35V will work but it is too big for the capacitance you will get. You do not need more than 16V. Lower max voltage = smaller size, which matters on a micro.
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Old 09-12-2004, 03:58 PM   #124
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Are you confused about POWER CAPACITORS?

A power capacitor is used to prevent the ESC from damaging itself.
Well, not really, but it prevents damage generated by the motor and battery
from hurting the ESC. When an ESC is switching on and off to give you throttle,
the electricity from the battery is being drawn vary fast. When the ESC switches off the electricity wants to flow. This is called a Ripple Current and will heat up parts
Inside the ESC. The power capacitor catches the Ripple Current and stores it,
Feeding the stored power back to the battier and motor on the off cycle of the ESC.
The side effect is a much improved mid-range throttle response, and a cooler ESC.
A cooler ESC means less voltage drop due to heat, and more voltage to the motor,
witch results in higher speeds.
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Old 09-13-2004, 11:40 AM   #125
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You could use 6.3 volt capacitors, you'd be overloading them but if you're lucky you could be within the manufacturing tolerance with 6.3 volt capacitor.
If you're unlucky, you've lost the price of one capacitor and smelt the wonderfully stomach-turning smell of blown capacitor, which also happens if you connect it backwards.

We usually use capacitors less than hour each day, five minutes at a time.
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Old 09-13-2004, 11:52 AM   #126
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SO DO WE REALLY NEED TO ADD TWO TO THREE POWER CAPACITOR OR IS IT OVER KILL? AFTER ONE WE SHOULD NOT SEE MUCH OF AN INCREASE IN PERFORMANCE RIGHT?
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Old 09-15-2004, 08:45 AM   #127
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Please stop shouting.

Number of capacitors doesn't matter as much as total capacitance. 1X10.000uf capacitor is better than 2X4.700uf or 3X2.700uf capacitors.
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Old 09-15-2004, 09:00 AM   #128
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SORRY I'M NOT SHOUTING. JUST THAT I'M AT WORK AND WE HAVE TO HAVE CAPS ON ALL THE TIME. SORRY IF IT SEEMS THAT WAY.
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Old 09-23-2004, 07:01 AM   #129
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10 ns schottky diode SBL3040 rated 30 amp @ 40 volts

I use 6.3V 3300 micro farad capacitor pull from computer motherboard ( low esr ). If you want to get lower esr ( internal resistance measure by ohm ) you could double the cap in parallel.

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Old 09-23-2004, 07:17 AM   #130
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Honestly speaking, I can't tell the difference with or without power caps. The car is running neck to neck with big azz cap's cars. I just installed it because of trendy reason.

The reason I use 6.3V cap is faster charging to get full capacity of the cap. Using higher voltage rating cap such as 10V is good for long lasting life of the capacitor, but I'm not sure it will reach full capacity, especially if you accelerate and brake often ( technical circuit ).

If the cap gets hot it means it's working.
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Old 09-23-2004, 07:33 AM   #131
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Quote:
Originally posted by asw7576
Honestly speaking, I can't tell the difference with or without power caps. The car is running neck to neck with big azz cap's cars. I just installed it because of trendy reason.

The reason I use 6.3V cap is faster charging to get full capacity of the cap. Using higher voltage rating cap such as 10V is good for long lasting life of the capacitor, but I'm not sure it will reach full capacity, especially if you accelerate and brake often ( technical circuit ).

If the cap gets hot it means it's working.
You're somewhat wrong here; The voltage aint an expression of how high a voltage it can charge, it's only the limit of how high a voltage it can work with without being damaged.

In other words, your 6,3 volt cap will die an early dead. The prove is, that your cap gets hot - it shouldnt during use within the rated specs.

A capasitor is very different from FET's and resistors - the powerloss is very very small, compared to those - have you ever seen a capasitor with a heatsink? No.

What makes a real difference, is the rated capasity - the higher the Farads, the more milliamps, it can carry and will draw before it's full.

If you need faster recharge of the cap, use higher quality caps and/or smaller caps in parallel to get the same capasity as with a big one.
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Old 09-23-2004, 07:56 AM   #132
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Running a 6.3V cap is bad idea. 6.3V is the rated maximum voltage the capicator can take before the dialectric between the charge plates breaks down and you arc across the capacitor. The reason you cap is getting hot is because you have current flow from positive to negative. You basically have added a resistor to you battery. Not good for maintaining you voltage. The arcing can also cause radio interference and stuttering during acceleration.

You need to run at least a 10V rate cap but a 16V is completely safe. Also, 2 smaller caps in parallel with the same effective capacity is better better than 1 super large cap. Effective ESR drops as you add more small cap's in parallel. This will allow the cap's to charge and discharge more rapidly which will keep your battery voltage at a more constant and higher level. Constant voltage translates to more punch when you grab throttle.

My $0.02
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Old 09-23-2004, 11:43 AM   #133
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Oops..... so sorry guys..... bad information. I check again, it was Rubycon 16V 2200uF

The capacitor was rather hot ( almost as hot as my battery ) because I wasn't using any schottky diode yet. Interestingly, the cap and esc were so much cooler after I installed big azz schottky diode

BTW, the 6.3V 3300uF cap is installed in my other car, and truly I don't experience any different with 16V 2200uF cap. It doesn't pop or leak.
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Old 09-23-2004, 11:55 AM   #134
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JUST TO CLARIFY ESR IS ELECTRO STATIC DISCHARGE.THE LOWER THE # THE QUICKER THE CAP WILL RE-CHARGE WHICH WILL RELEASE ENERGY FASTER.
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Old 09-24-2004, 04:58 PM   #135
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Actually ESR means Equalant Series Resistance, but your right that higher ESR means capacitor acts slower, both to store and release power.
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