500F... that is HUGE from a capacitor standpoint.... wow.

 

I used a multimeter to do it. and shown 0.04A TO 0.18A.

Depending on the meter and range, you could have been inserting hundreds of ohms in series with the cap. This is a frequent mistake by newbies. Trying to measure the current with a DVM changed the circuit enough that you can't take meaningful measurements.

A DVM measures current by introducing a resistance in the circuit and measuring the voltage across it. You'd be far better off inserting a small resistance (less than an ohm) and measuring the voltage across it.

 

I don't use the current measurement range very often - sometimes you blow a fuse doing that and its too much hassle to find and install a replacement. Instead I have several shunt resistors that I regularly use, most are precision, and measuring the voltage across them I have not blown any more fuses, and I know what the burden resistance is.

 

Charging capacitor 500F from PS 3.3V through resistor 3Ω.
It takes 42 minutes for capacitor voltage 2.7V.

 

Charging capacitor 500F from PS 3.3V through resistor 3Ω.
It takes 42 minutes for capacitor voltage 2.7V.

View attachment 233945

Thanks.
I'll try this one.