charging capacitor

[joeyd71]

so i heard that it is true that you need a resistor in order to safely charge a capacitor. my understanding is that the resistor is to prevent so much energy from entering the capacitor all at once.

but what if i were to hook up a "trickle charger" to the capacitor? because in theory it is supposed to slowly charge a car battery, wouldn't it have the same effect if i hooked the trickle charger up to my capacitor?

let me know if this is a good idea or not.

Thanks,
Joe

[luka]

well, you are right, sort of... you need resistor to limit current, I see no diffrence if you need to charge caps to 12v or 400v, if energy needed will stay the same

[jol50]

I think it is more the damage it can do, the big spark, burns on the terminals, fire hazard, etc. I charge it with a 12v test light. I always use that to charge/discharge because it is sitting in my tools anyway. If you had to use a charger, just hook it up before you turn it on. It only takes a second or two for a 1f with my test light.

[joeyd71]

i'm not too concerned with the fire hazard.

but here is another question for you-
say i charge the capacitor, will it lose its charge if it is not connected into the circuit within like 20 seconds? or once you charge it, it will hold that charge for a while?

[luka]

it will loose it, but I found i can easyly hold it several hours. First smps I tried, mains power... over night, next morning still had voltage to scare me a lot, but here we are talking low voltage, still, charge will hold. But you can always use resister to drain it of its power