Quote:
Originally Posted by Ecky
I think I may have chosen the wrong LEDs - they went from bright to dark in a matter of minutes, with the cap bank stabilizing around 12.5v. I'm thinking rather than 30ma continuous forward current (100ma peak), I might want something more like 2-5ma, and/or a slightly higher voltage.
On the other hand, they'll probably very aggressively keep the caps in balance.
Maybe it was because it was the first time I'd charged them? I'll keep an eye on it and see.
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Yeah, keep the caps on the charger for half a day and then see what they settle out to. Measure each cap to see how closely the voltage matches the others.
If you had an adjustable power supply (I highly recommend one), you can take a spare LED and measure current draw at various voltages. The ideal activation voltage would be somewhere around 2.5v, with lower voltages barely flowing any current at all, and higher voltages flowing higher mA. A settled voltage of 12.5v suggests your LEDs flow pretty high until about 2.1v each.
I had tested various LED and diode combos in my parts bin before settling on the ones you see in the photo with the yellow caps. BTW, there is an additional diode in series with the LEDs because the LED alone was not a sufficient voltage drop. It would have been too much voltage for those red and green LEDs without the diode in series.
Other color LEDs might be closer to the voltage you want.
I'd also charge all caps up to the same voltage and let them sit for several days to see if they bleed at the same rate. You want to identify a dud before putting these to work. I know Maxwells to be very high quality, but many of the other brands have been known to ship duds.