Quote:
Originally Posted by Enki
Actually it seems to me that when the cells are charged and maintained, they don't leak down as bad. The first time I charged them, leakdown was pretty bad. They got down to 12.62 volts in 19 hours, but then I recharged them; see the attached image for stats before and after the recharge. Note that my bank has *no* cell balancing, which would likely improve leakdown further.
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Excellent post!
I've been charting the leakage of my 350F series of capacitors over the course of the past few days and will put it into an Excel sheet soon. Mine are balanced by the LED/diode method, so most of the initial "leakage" is just driving those lights. Do you find balancing to be unnecessary? I've wondered if higher charged cells would also have a higher leak rate, effectively balancing themselves. This would be a worthwhile experiment since eliminating the balance circuit simplifies things and lowers the parasitic drain.
Your parked parasitic draw of 250mA is extreme. I'd only expect that draw on a cheap aftermarket alarm system install, or a failing electrical component. Have you measured the drain after letting the car sit for a longtime without opening the door or messing with the door locks? I ask because my TSX has a higher draw just after parking, and whenever the door has recently been opened. It eventually settles to 40mA.
The 14v-10v 560mA figure in your spreadsheet is very helpful because I found conflicting methods of how to calculate it (please PM me your spreadsheet or the formula). It looks like my truck, with a 20mA parasitic drain, can only sit for 28hrs before your 3000F caps would fail to start it. I believe I can get the drain down much further after disabling a thermometer with constant LED back-light. I'll try that tomorrow.
Can you explain the V+W -> A and the V+A -> W table a little further? I know how they are calculated, but I'm just wondering what the figures have to do with replacing a car battery with capacitors. I'm also curious what you are planning with those resistor calculations.
I bought 2 amp loggers to measure the amps going into, and out of a capacitor or battery so that I can determine the charge/discharge efficiency between capacitors, LiFePO4, and lead-acid. When I start getting more than 1 day off per week, I'll start experimenting and share my methodology and results.