Quote:
Originally Posted by cts_casemod
The alternator will most likely be subject to a bit of s strain while charging a capacitor from 9V to 14V, for example. It's a 'dead on' short circuit.
I currently have 12.8V LiFePO4 battery on my car and even that ended up blowing the bridge rectifier due to the CV charge employed.
I say a hybrid would be the best approach. Say 10Ah lithium battery than can be had for $60 coupled with the capacitors to aid on starts. Probably a 200F would suffice.
I like the idea of a small solar panel to trickle charge... never used use, but I'm seriously considering it.
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Alternator output is regulated, so the strain should not exceed rated output. Perhaps the rectifier blowing was coincidence.
I like the 10 Ah paired with the capacitor idea the best. I'd go with 6x 350 farad caps since they are most common and cheap kits are available on Ebay.
Solar charging would require a balance circuit since neither caps or LiFePO4 is tolerant of even slight overcharges. A small solar panel can easily exceed the parasitic drain of vehicle electronics plus self-discharge and over-volt both the caps and the battery.
I had a small solar panel over-run the LED balancers I have installed on my caps, but fortunately I discovered the problem before the voltage went much above rated.
Quote:
Originally Posted by cts_casemod
My point is that super capacitors are viable if they replace the battery altogether, I don't think I would pay the premium just for the added longevity of the starter battery, when a smaller size deep cycle VRLA or lithium would achieve just as much, unless it was the case for extreme low temperatures.
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I tend to agree. Supercaps can replace a battery on cars with extremely low parasitic drain, which is almost no current vehicle due to remote entry, car alarms, and radio. My truck has a 0.0057 Amp draw due entirely to the radio memory. If I took the radio out, I think there would be zero parasitic draw. A small solar panel can keep it topped off.
A supercap/LiFePO4 combo makes sense if the goal is to reduce weight, but LiFePO4 is not tolerant of charging in sub-freezing conditions.
When my Prius battery finally dies, I'll replace it with a LiFePO4 since it's located in the temperature controlled cabin, and the OEM replacement cost is something absurd like $250.