Howdy folks,
Ive got a 95,000uF / 15V electrolytic cap that I suspect has gone off-value and I need to measure it. None of my meters can handle a value this large, so I need a technique. Heres what Ive got so far:
0.095F × 1000R = 95 seconds time constant.
I charge the cap to 15V, apply the resistor and start timing until the cap falls to 0.63 of Vo (9.45V), which takes around 90 sec. I take this to mean the cap is a bit down in value, but not bad - maybe 5% off?
But I dont think my procedure is right.. what are the correct numbers / calculations? Because when I charge this cap direct from a 15V supply (no resistor), it draws near zero surge current - and I'd expect quite a surge - like to the limit of the 1A supply.
Thanks.
Ive got a 95,000uF / 15V electrolytic cap that I suspect has gone off-value and I need to measure it. None of my meters can handle a value this large, so I need a technique. Heres what Ive got so far:
0.095F × 1000R = 95 seconds time constant.
I charge the cap to 15V, apply the resistor and start timing until the cap falls to 0.63 of Vo (9.45V), which takes around 90 sec. I take this to mean the cap is a bit down in value, but not bad - maybe 5% off?
But I dont think my procedure is right.. what are the correct numbers / calculations? Because when I charge this cap direct from a 15V supply (no resistor), it draws near zero surge current - and I'd expect quite a surge - like to the limit of the 1A supply.
Thanks.