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Inverter advice

  • 16-10-2022 7:05am
    Registered Users Posts: 387 ✭✭ nokiatom

    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?


  • Moderators, Motoring & Transport Moderators, Sports Moderators Posts: 6,250 Mod ✭✭✭✭ fergal.b

    The size of inverter you need depends on what you want to run off it, something like a coffee machine can be close to 2000 watt a kettle 1500 watt and a microwave 1000 watt so look a what you have and add up the amount of watts you would use at any one time then add a few more to cover yourself. On my boat I have a 3000 watt inverter run off 3 110 amp batteries. Cable size may change if you have a long distance between battery and inverter.

  • Registered Users Posts: 387 ✭✭ nokiatom

    Thanks for your reply and chart, its very useful. Im new to this solar power system and i dont have solar panels yet. I was given 2 batteries which are not new but hoping I can experiment with them connected to small appliances such as pc with router and speakers, fridge freezer and maybe a couple of 100 watt lights. I dont want to invest in solar panels yet as I would like to test the condition of the batteries first.

  • Moderators, Motoring & Transport Moderators, Sports Moderators Posts: 6,250 Mod ✭✭✭✭ fergal.b

    To run a pc you will need a pure shine wave inverter, the fridge freezer can take a lot of power at start up and will probably be the biggest draw on the batteries, lights if you go with LEDs will use very little power. Batteries play a big part and are probably the biggest investment, are the ones you got leisure batteries or starter batteries, they are usually second hand because they were not doing their job so I wouldn't trust them to be reliable. I'm no expert in all this but have done alot of research for my setups so that they meet my needs, might be worth calling "cozy campers " or "" for the right advice.

  • Registered Users Posts: 387 ✭✭ nokiatom

    the batteries are Victron gel deep cycle. I was told they are fairly old but rarely used. I did charge one up and then connected a load to it (two car headlights 55w each), after 11 hours the voltage had dropped to 10v and then disconnected it. I then recharge it again with a Ctek MXS 5.0 with Recond selected and i do find a small improvement everytime. I still have to test the second battery so just hoping I can experiment with something small soon

  • Registered Users Posts: 5,724 ✭✭✭ Ubbquittious

    B'Careful with what inverter you actually buy. There is a ferocious amount of utter Chinese sh1te ones out there. You'll find out that certain appliances won't run off them despite them being sold as "pure sine wave" and "starting power" figures being greatly exaggerated

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  • Registered Users Posts: 387 ✭✭ nokiatom

    So what would you suggest as an inverter for starters. I'm only experimenting in a small way and nothing is going to be permanently connected. I just want to see as well are the batteries any good for a small setup. If they were in reasonable condition I might then look at solar panels, otherwise I would have to charge them with a battery charger

  • Moderators, Motoring & Transport Moderators, Sports Moderators Posts: 6,250 Mod ✭✭✭✭ fergal.b

    I like the victron stuff and have a 3000 watt smart inverter on the boat, not cheep but good quality.

    Add up the watts you think you will need and then doubble it 😉 "marine parts direct in Swords " have a selection of smaller inverters, for victron stuff I use the smart inverters connect to an app on your phone so you can keep an eye on what power you are using and how much you have left. If you are thinking of going solar down the line you may need other bits of kit like a MPPT controller so it's worth sticking with the same make like victron as the parts can communicate to one another.