Quote:
Originally Posted by teoman
What would be the requirement for a newer car with start stop feature, like a passat.
I wonder if 2*5 of the 3v ones would suffice?
I do not mind carrying the initial charge of the day with me,
A lithium ion battery and a boost coverter to charge the capacitors up to 15V or to charge charge each one individually to 3V.
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You wouldn't need 2x to accomplish this. A single series cap bank would give you a few starts without charging.
The downside is you would often lose remote lock/unlock, radio presets, etc from the caps draining down.
I'd keep a small battery connected to eliminate the hassle of charging the cap bank up each time, and losing presets.
Don't charge the bank to 15v. That doesn't leave enough headroom and you are bound to overcharge one of the caps. I'd charge to 14v and then let the alternator decide what voltage to maintain once the vehicle is started.
Quote:
Originally Posted by AlexanderB
I might also get a small solar panel and a little (custom) charge controller to keep the battery topped up, so I can keep my clock and central locking and what else connected if the car sits for more than a week or two.
For $325 I could also install a pile of lipo's that 3x the stock battery capacity, but that wasn't the point, the point (for me anyway) was saving an additional 2% off of the total vehicle weight by deleting the lead.
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The battery in my Acura has died, so I'm considering a series string of 350 farad caps to start the car, and a small LiFePO4 battery in the passenger compartment to keep the caps topped off.
LiFePO4 doesn't tolerate charging below freezing, so I wouldn't consider putting them in the engine bay in climates where freezing is likely.
Rather than mess with a charge controller or subjecting LiFePO4 to cold/hot temps, the best solution is likely to get a very small lead acid battery and pair it with caps.