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Please give me an alternative to the big 12V system I've planned

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  • Please give me an alternative to the big 12V system I've planned

    New here - thanks in advance for any & all help!

    I'm in the planning stages of an off-grid system for a 'skoolie'. The need is essentially a home on wheels, capable of operating remote, complete with two full-time 'office spaces', so our power needs exceed what might be considered recreational.

    Until reading the 12V sticky, I had planned on:

    1) 6 x 1200Ah 2-volt batteries wired in series (4/0 cable)
    2) A 4' run of 4/0 cables from the battery bank to a 2000-W inverter/charger (across a 250A breaker)
    3) 4 x 300W, 36V panels, Each pair on a separate 50A MPPT controller.
    4) The required hardware (not yet researched) required to charge off the alternator as well (for a total of 3 potential charge sources... alternator, solar, and shore/genny)

    I understand the advantages of a 24-v system, but with all the 12V loads we'll have (I'd like to keep as many 12V items 12Vs, as they're easier to source if nothing else), it seems problematic to add in the 24/12 conversion inefficiency on top of the inverter loss, plus I'd really like to charge via alternator & don't know how I'd do that otherwise (have looked for dual-alternator kits, but can't find any, and don't wish to add in proprietary/one-off/homebrew parts that could fail 'in the field' leaving us high & dry).

    I've cut as many corners on power use as I can... we need those Amp Hours. So if you were me, what would you do? Everything I've planned seems to contradict the advice I've read, which I'm sure is there for a good reason. But I don't know the best way to implement the necessary change.
    Last edited by magicbus; 05-13-2019, 03:36 PM.

  • #2
    Look into the balmar gear, for a 2nd alternator, 24V
    or at least their high output alternator for heavy 12V charging. Most "factory" alternators heat up and reduce charging amps after 10 min.
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A



    • #3
      I've had pretty good luck finding 24v items. The only item that I am going to have to convert 24v to 12v - My Webasto heater

      +1 on the Balmar alternators. I have used them in marine applications and found both the products and customer service are great. I would install one in a heartbeat IF I could find a bracket to fit my 2002 Cummins 8.3........
      Last edited by PNW_Steve; 05-13-2019, 12:11 PM.


      • #4
        You could use the 24 volt system for all inverted (AC) loads and add a small 12 volt system for the few small 12 volt loads. Not sure if this remedy would be practical on the Skoolie. I have this set up in Baja.
        2.2kw Suntech mono, Classic 200, NEW Trace SW4024