How to charge a 48V Battery Bank (for Solar efficiency) with an alternator???

tmckenna

Solar Enthusiast
Joined
Jul 8, 2020
Messages
124
Hey guys, currently have a pretty simple setup with on 300ah LifePO4 and an Amazon inverter, but am in the planning phases of my "final" configuration. I was originally planning on doing a 48V battery bank for the solar benefits (more wattage potential) and using a Daygreen DC to DC converter to power the DC circuits in the camper. But I will be purchasing an older 7.3 Ford which you can get pretty beefy alternators for, I've seen up to 390A.

Now my question is that, because obviously the alternator is putting out 12V and my battery bank will be 48V how do you recommend getting the alternator to charge the camper battery. I've looked for 12V to 48V DC to DC converters and they don't support much current. If there is no answer and I have to choose between the 48V for the solar or 12V for the alternator thats fine, was just curious if there was a solution?
 

Boondock Saint

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Joined
Apr 8, 2021
Messages
658
These DC-DC are current to voltage converters. They convert your alt current to appr 4x the voltage which is why the output current is less. 20A @ 48v is still a decent charge if you do much driving. As you know in the 48v camp choices are more limited. I bought the Daygreen unit for my rig, then regulated by a Victron SCC and Cerbo GX as part of overall SOC charge management.

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tmckenna

Solar Enthusiast
Joined
Jul 8, 2020
Messages
124
These DC-DC are current to voltage converters. They convert your alt current to appr 4x the voltage which is why the output current is less. 20A @ 48v is still a decent charge if you do much driving. As you know in the 48v camp choices are more limited. I bought the Daygreen unit for my rig, then regulated by a Victron SCC and Cerbo GX as part of overall SOC charge management.

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Ah that makes more sense I guess. i see daygreen makes one up to 40A which is pretty good (1920W). That might be a good option. At this point I'm thinking it may be more cost effective to just do a second solar charge controller rather than having 2 additional DC to DC converters (step down for 12V camper circuit and step up for alternator charging). Could just keep the battery bank 12V and use a Victron DC to DC converter to charge the batteries from the alternator and however many solar charge controllers I need to support the wattage that I'd have, especially considering high current Daygreen stuff isn't exactly inexpensive.
 

tmckenna

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Joined
Jul 8, 2020
Messages
124
I don't see why not, but could I run 48V to 12V converter off a 48V charge controller to charge a 12V battery bank?
 

RV10flyer

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Joined
Mar 8, 2021
Messages
126
I have 1000W PV, MS 250 SCC, Magnum 4024 Inverter, 24V (28V) 50A aircraft alternator, 9000Btu Mini Split HP on my Std Chevy Express Van. Just stop by your local airport. Plenty of “Ford” or “Delco Remy” alternators with burnt up stators. Pilots love draining the battery while trying to start the engine once every 3 months. Then instead of putting a charger on for a few hours, they fry the alternator. Take it to an alternator shop to get rebuilt for less than $150. Fabricate a bracket, install a pulley, serpentine belt, 10K ohm potentiometer so that Alt output current can be controlled from drivers seat, volt/amp meter, thermistor temp sensor epoxied to rear bearing or stator area, 24V voltage regulator with voltage adjustment potentiometer dug out and wired to 10K potentiometer.
 
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