Solar and Alternator Combination

kj67072kj67072 Registered Users Posts: 5
I am very new to the solar community. I have recently gutted a 1995 G20 Conversion van and I am in the process of turning it into a camper. I have done some research and believe I understand some basic ideas/components about solar. However, I am finding it difficult to locate information regarding charging a battery with both solar panels and the alternator of the van. Is this possible? If so how would the two parts be linked together? I currently have a battery post on the frame of the van directly behind the drivers seat. It was used for the electrical bed that I have removed. Would it be possible to use this incoming battery feed to charge a secondary battery with the alternator? My thoughts were to hook up an AGM deep cycle battery to the alternator and eventually get solar panels when I have the money. I am planning to install low voltage LED lights throughout the van and also have an inverter to charge a laptop, camera batteries and some other electronics from time to time. If I have to hold off on the inverter until I get solar panels that is fine. The only other component I am considering is a 12v bilge pump if I decide to install a fresh water tank under the van. Thanks ahead of time! Looking forward to finally understanding this stuff!!


  • zonebluezoneblue Solar Expert Posts: 1,218 ✭✭✭✭
    There are a variety of ways people do this. The most common way is to use a start bank and house bank of the same voltage, and use a device variously called a dual battery isolator. They work by only connecting the house bank to the vehicle electrics when the alternator is running. Shop around as they vary from simple relays, diodes to smart mosfet based devices. Once youve dont that, you can add your solar charge controller into the house bank.

    One word of advice, if you are starting from scratch, is to give serious consideration to using a 24V house bank. This similpfys a lot of things on the solar side. You can get 24V pumps and fridges etc, so not a hardship there. But if the alternator is 12V, then thats trickier. However for me it boils down to the ratio of moving to stationary. With mine i was stationary more than moving,  hence dependence on the alternator was pointless, and dictated a 100% solar solution. And my bus was 24V alternator anyway, if i ever needed a redundant backup.
    1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,

  • kj67072kj67072 Registered Users Posts: 5
    Thanks for the advice!
  • kj67072kj67072 Registered Users Posts: 5
    So I have looked around a bit and I must say I am not sure exactly what to get. I am thinking this will do the trick but I am not sure about the amperage. 
  • BB.BB. Super Moderators, Administrators Posts: 32,015 admin
    Assuming it is a good quality product--Yes, it would do what you are asking. Basically connect the two battery banks together when the alternator is charging.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 6,032 ✭✭✭✭✭
    Whatever you buy, I would make sure that West Marine sells it !  Or, Camping World if this is an RV.
    To me, that is an indication of quality and availability for the long haul.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
    E-mail [email protected]

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