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Could a solar charge controller be connected to your alternator and instead be used as a sort of battery isolator to charge a house battery in an RV?
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No Sir, that is what they make Electronic Battery Isolator for. Lot less expensive to. Do not use Mechanical Isolators. Use Electronic as they can be set for any battery type. Let me know if you need a link. We are talking $30 to $70 for a good one up to 70 amps and more if needed.MSEE, PE -
What electrically prevents this from working? It would be nice because you would be able to monitor current draw and charge current to your house battery, and a use for a left over controllerComment
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Solar Charge Controlers are designed to work with a Current Source, not a Voltage Source. Your vehicle alternator is a Voltage Source. A Solar Panel is a Current Source. You can still monitor and measure current with a Electronic Isolator. You can even see more Info like both Charge and Discharge current.
You can try if you have a PWM controller, but no way will a MPPT controller work.MSEE, PEComment
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My theory was that the solar input on a charge controller is not "throttled", it will take whatever current it can be supplied. Is has very low resistance. If you were to hook it to a power source such as an alternator, it would probably try to draw the maximum current output from the alternator and then fail dramatically.Comment
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Not high enough voltage out of your alternator. Your alternator will only charge up to about 13.4 to 13.8 volts depending on make. PWM charge controller cut out at 14.4 for FLA batteries
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That's not the problem; you can set output current limits on most MPPT controllers. However, no controller can boost voltage; they can only drop it. And since your alternator is running at around 13.8 volts, and since all controllers have _some_ voltage drop, you won't get enough voltage to charge reliably.Comment
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