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Inverter

  • 16-10-2022 12:27am
    #1
    nokiatom
    Registered Users, Registered Users 2 Posts: 454 ✭✭


    What size inverter would I need for two 12v batteries (connected in Parallel) 150 amp each.

    Also what size cable would I need to connect the batteries together?

    And what size fuse would I need?



Comments

  • #2
    Pete67
    Registered Users, Registered Users 2 Posts: 1,257 ✭✭✭Pete67


    That really depends on the load you want to supply from the inverter, you would select the inverter based on the total load in Watts, with an additional allowance for starting current if you are running any motors.

    Each 100W will draw about 10A from a 12V battery bank, so add up the loads you want to run and then size the battery cables (and switchgear, fuse etc) to handle that current. Keep the battery cables as short as possible to minimise losses. There is no simple answer for cable sizing, it will depend on the load current, length of the run, cable material, type of installation, allowable voltage drop, max allowable cable temperature etc.

    As an example, assuming copper cable and a 2m long cable run, a 100A load on a 12V system will need 27mm2 cables to keep the volt drop below 3% - but that's not a standard size so you would specify 35mm2 as the next available size up. That would probably suit a 1000W inverter, maybe a little bigger if it is only run at full load for a short duration and only occasionally. 35mm2 sounds like a large cable, it's not really, for single core cables such as battery cables, the wire diameter is less than 7mm.

    You can reduce the cable size required by increasing the battery voltage, but that may not be practical depending on the application, and you would need an inverter rated for the battery voltage. For this reason most domestic solar battery installations run at 48V. There are several online calculators to help with cable sizing calculations once you know the load, length of run and installation details.



  • #3
    nokiatom
    Registered Users, Registered Users 2 Posts: 454 ✭✭nokiatom


    https://www.boards.ie/discussion/comment/119758738#Comment_119758738

    Thanks for a great reply. I'm new to this so I want to experiment with a simple system. I would be only powering a fridge freezer, a pc, maybe 2 small lamps and a usb hub for charging small batteries. Everything would be in the same room.

    I'm guessing the max load would be about 700watts but not everything will be drawing power at the same time



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