Running AC and DC off of the same battery bank

Hello,

I am curious about running DC loads off of my 48Vdc battery bank. I am using 6V batteries.
I am using an inverter to run 120Vac and 240Vac loads. The loads are around 6000 watt hrs/day.
I would like to run a DC well pump or booster pump.

Is there anything I should be aware of, is this a normal practice?
Wiring advice?

Any help is appreciated.
Thanks,
Island Mon

Comments

  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Running AC and DC off of the same battery bank

    if the pump is made for 48v, then no problem as long as the batteries can take the total loads without draining down too far. most pumps aren't 48v though so a voltage converter would be needed to take it down to the desired voltage at the desired current.
    edit to add:
    don't forget that an inverter is a dc load to the battery bank and putting a converter to the batteries would also be another dc load to the battery bank.
  • dwhdwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Running AC and DC off of the same battery bank
    Island Mon wrote: »
    I would like to run a DC well pump or booster pump.

    Is there anything I should be aware of, is this a normal practice?
    Wiring advice?

    Any help is appreciated.
    Thanks,
    Island Mon


    It's a normal practice for golf cart wiring - they commonly tap 12v off a 36v or 48v battery bank to power the lights.

    For heavier loads though (like water pumps) I would go with neil's advice and use a 48v-12v converter and tap the whole battery bank to distribute the load rather than just tapping one or two of the batteries in the bank.
  • mike95490mike95490 Solar Expert Posts: 8,009 ✭✭✭✭
    Re: Running AC and DC off of the same battery bank

    I have plans and parts list & gerber files for PCB, for a 120W, 94% eff 48-12V DC-DC converter. Gives very pure clean DC, core is a commercial telcom product. Parts cost is about $100, and you need surface mount soldering for some tiny LEDs. I can send files if you want, but I think pumps require more than 100w.

    You could tap 12V off your bank for a few tiny LED's, but that WILL load some cells more than others, and you may have to Equalize more often to keep things in balance, risking killing 12V worth of batteries.

    Grundfos SQFlex pumps run from 30 - 300VDC with internal converter (I think that's how they do it)
    Our Host sells them: http://store.solar-electric.com/grsoposuwapu.html
    Powerfab top of pole PV mount | 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

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: Running AC and DC off of the same battery bank
    dwh wrote: »
    It's a normal practice for golf cart wiring - they commonly tap 12v off a 36v or 48v battery bank to power the lights.

    For heavier loads though (like water pumps) I would go with neil's advice and use a 48v-12v converter and tap the whole battery bank to distribute the load rather than just tapping one or two of the batteries in the bank.

    tapping batteries for 12v in a higher voltage battery bank is something we never recommend doing here even if it's for very small loads. it does, as mike said, present inequities in the battery bank setting up the need to equalize more often and if not equalized then 1 battery will fail early. even the extra eqing will cause more maintenance too.
  • mike95490mike95490 Solar Expert Posts: 8,009 ✭✭✭✭
    Re: Running AC and DC off of the same battery bank

    I've just found another source for some commercial telcom 600W converters, a "sample" evaluation board is $99
    >96% eff but only 55V max DC input.

    http://vicorpower.com/ http://www.vicorpower.com/products/vichip/ibc/
    search for part I048C120T060P1 16V version avaib too.

    data sheets http://www.vicorpower.com/documents/datasheets/ds_ibc.pdf
    Powerfab top of pole PV mount | 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

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • sodamosodamo Solar Expert Posts: 54 ✭✭✭
    Re: Running AC and DC off of the same battery bank

    We do it. Our pool pump is 48vdc. A direct line from the dc side of our system to its dedicated dc controller. Everything else runs from our FX3048 inverters.
    The pump is a Lorentz. Check them out as they have both surface and deep well pumps that run off this controller

    David
    10.04 KW panels
    3- FM80 CC
    4- FX3048T Inverters
    FNDC, MATE3
    OpticsRE
    12 - 1350ah Rolls Surette 4v
    24kw generator (Chinese, built in Az)
    10kw MEP803A backup generator
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