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charging a low impedance super cap

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bigfarmerdave

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I'm going to be charging a super cap (haven't picked the cap yet) and I'm trying to pick out a regulator to charge it. Lots of regulators have over current protection and shut down when tripped, then start up again.... and I'm afraid it will oscillate like that possibly causing permanent damage. Are there any regulators that max out at a certain current (say 3-4A) and just keep conducting at max current rather than shut down when they see a low impedance load?
 
I'm going to be charging a super cap (haven't picked the cap yet) and I'm trying to pick out a regulator to charge it. Lots of regulators have over current protection and shut down when tripped, then start up again.... and I'm afraid it will oscillate like that possibly causing permanent damage. Are there any regulators that max out at a certain current (say 3-4A) and just keep conducting at max current rather than shut down when they see a low impedance load?

Just charge the cap with a series resistor installed such that it can't draw more then the max rated current of your regulator. It will charge to full voltage, just take a little longer.


Lefty
 
Or use an NTC thermistor. It has high resistance when it first turns on limiting inrush current. BUt after it heats up it's resistance gets lower to remove some of the resistance from the path.
 
To charge a SuperCap of 700F (new types 1,200F) it will take quite a while using a current limiting resistor reducing the charge current to 3-4A.

I suggest to use a power supply which can handle 10 to 15A.

(Don't exceed the nominal voltage (5V) of a SuperCap. It will turn into a bomb!) :mad:

1F is the capacitance of a capacitor allowing 1A of current flow for 1 second. Charging at a current of 3A the 700F cap will be fully charged after 233.33 seconds (3 minutes and 53.3~ seconds) assuming no losses.

Boncuk
 
Unless you use some kind of switched mode charger, the charge-discharge efficiency will always be 50% or less.
 
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