Quote:
Originally Posted by Crashy
I've had them on my solar setup and gave them the boot. The problem is high ESR and high self discharge. At 2.7v per cap, it's quite difficult to reach the voltage level you are working at. They must be connected in series which divides the capacitance and multiplies the ESR. They must be balanced. Using your argument, to avoid high self discharge, stay away from the voltage limits.....that would require even more caps in series, thus decreasing overall capacitance and increasing ESR (losses). Once again, more losses cannot possibly improve efficiency.
I found that my 6S pack did not charge quickly at all. From zero to 6v it was quite decent current over 2 minutes (too long!), but quickly dropped off and took 20 minutes total to reach 14v. And as soon as it was disconnected from the charger voltage dropped like a stone. And capacity out vs in was only 20%. 80% loss...no thanks
I know several people who have huge banks of them in 48v systems and they often comment on how warm they are. These are connected 24/7. Any time an electrical component is warm that's losses. A huge bank of them getting warm = huge losses. Doing this 24/7 = idiotic
I've been following Robert Murray Smith for years. Eventually we will perfect caps and they will replace batteries but we are not even close
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You had defective caps, which I have heard is common. My 6s bank charges up quickly and takes months to drop a volt. Never any heat, and minuscule charge / discharge losses due to the extremely low resistance. Maxwell's BCAP series are rated at 0.29 mOhms. My 6s never needs balancing as they naturally find balance and are closely matched.
There's nothing more efficient than capacitors for accepting a charge and then discharging. There are serious drawbacks as you say, such as greatly diminished capacity when connected in series, inability to hold voltage during discharge, and inability to accept an overcharge.