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Old 05-02-2010, 06:03 AM   #1
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Default Capacitors on Speed controls

Hi Guys,

I want to know what a capictor does fon a speedy control. I am running a QC3 Speedy forbrushed 540 motor.

I currnetky dont have a capacitor, and speedies i use to have always had a capictors, but this one doesn't, i am starting to wonder if i need to have one.

Some people say it gives yo ua boost.

What size capcitor should i use and how do you attach it??

Regards

Brad
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Old 05-02-2010, 06:45 AM   #2
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LOL wanting that winning edge brad?

Anything to get 0.0001 kp/h down the straight
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Old 05-02-2010, 09:01 AM   #3
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Capacitor stabilize the voltage to your esc...lower esc temp, better punch ..
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Old 05-02-2010, 09:24 AM   #4
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how much capacitence do we need exactly then?
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Old 05-02-2010, 09:36 AM   #5
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Old 05-02-2010, 06:04 PM   #6
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the capacitor smoothes the large'ish voltage spikes caused by the motor and the ESC transistors switching at high speed. It doesn't give you any boost, the amount of energy stored in the cap is miniscule.
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Old 05-02-2010, 07:37 PM   #7
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i would like to reinforce what gameover said. the capacitor is to smooth the voltage spikes created by the ESC since it is PWM (pulse width modulation) and thereby keeping the speed control cooler. to see any noticible difference in punch you would need a capacitor almost as big as your battery. older speed control with big cases had the capacitor(s) inside them but most new high-power speed controls have them external.
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Old 05-02-2010, 09:21 PM   #8
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Caps also serve the purpose of absorbing spikes when braking. When the ESC applies brakes the motor is turned into a generator, and can produce a large voltage spike, which can cause issues in the ESC and batteries if nothing is there to absorb it.

Make sure to use low ESR (equivalent series resistance) caps and solder them as close as possible to the ESC board (also to keep to overall resistance as low as possible). The caps should be rated to 105C, and it is better to use multiple caps instead of one large cap (e.g. three 500uF caps in parallel instead of a single 1500uF cap) because the multiples allow better heat dissipation.
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