I am wanting to remove the alternator on my Metro and go to solar recharging. The typical idea is just replace the alt with a solar cell and have at it. But that means the car is running on low voltage and the headlights and other accessories can get dim. So my idea is use a roof mount solar panel and charge controller to charge a deep cycle battery. This battery feeds a heavy duty riding mower battery that is hooked up normally to the metro. The deep cycle will connect to it using a step up converter similar to this:
Amazon.com: DROK DC Converter Voltage Regulator 8-32V to 9-46V 12/24V 150W Boost Step Up Power Supply Module: Electronics The typical step up converter can convert 8-30VDC to 8-40VDC or so. I just need either a large module or multiple modules to get the current I need at 14.4V to keep the main battery charged.
It can keep the main battery at 14.4V and all the electronics in the car will be happy. I already have LED lights and can rewire the heater blower to run on the deep cycle since it is probably the highest current draw and won't really matter if it gets lower voltage. If I remember correctly the engine needs a bit under 10 amps to run. I figure if I can get a sustained 25 amps out of the step up controller it should work out about right. If not I could always add another step up module and get more current.
The idea being that since the deep cycle can get low the solar can charge it throughout the day and build it back up. Then when I am driving the step up modules will keep the car running along happy. Trying to do everything with just one battery would mean that at the end of a drive at night I might not have enough power to start the car but with the deep cycle able to go down to 8V or so keeping the main battery fully charged I should be good for even a few hours of night driving with no problems.
Any thoughts on this setup?