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kfp673's avatar
kfp673
Explorer II
May 25, 2022

DC to AC help

Hello All. I know it has been discussed a million times but I'm struggling to find posts that start with "step 1". Feel free to simply point me to a post if you know if one.

We started doing a lit more boondocking 2 years ago. We upgraded to dual portable generators, added more water storage, and upgraded the single 12V battery to a pair of 6V. The 6V upgrade was huge and allows us much more time with out the generators. I might add to that but the next thing I'd like to do is power some AC devices such as coffee maker and TV off the battery. When I search, most of the inverters have AC plugs directly on them but I would like ours hard wired in. Ideally we would like to have any AC plug have the ability to run off the battery with an inverter before the panel but I'm not sure how to do that or which (relatively affordable) inverter to go with. If I learn from your replies that picking 2 or 3 AC outlets is easier then I am fine with that as well, but I still want it hardwired with either an auto switch over or manual switch but where it feels to the user as if you had AC power to the trailer. Auto switchover would be preferred.

Any help is appreciated and thanks in advance
  • There are probably several different ways of doing what you want. I will tell you of our way. I will try to make it simple so let's just start with the inverter (ours is 2000 W) which is wired to the battery bank in the front compartment of our fifth-wheel. [we have solar and lithium batteries, but I will leave out that part and just start with the inverter.]

    We have hardwired from the inverter to a normal 30 Amp outlet which is open to the outside of the trailer. This required a hole and a cover for the outlet:

    Outlet

    I could go into much more detail and if you PM me I will be glad to answer any questions. But this is how it works. I simply use the regular 30 AMP cable and plug into the inverter just as I would to a campground pedestal. Everything in the trailer is "live" just as it would be in the campground. Of course, I cannot power everything, but all my plugs are "live", my TV is live, my refrigerator and heater are live [if I have enough battery to run them.]
  • Automatic change over will limit the selection, cost more and is unnecessary. When the RV has AC power the battery charger will supply the DC to operate the inverter, less efficient but no need for any type of switching.

    Start with the AC watt load for your devices, add a safety factor even up to 2X for the inverter size. Inverters are generally MSW modified sine wave or PSW pure sine wave. Some devices like a TV may/may not work with MSW.

    Also the DC amp draw is about 11x the AC amp draw. Example: A 360W appliance would draw 360/120=3A AC and 33 amps DC. So be aware of the higher battery discharge when boondocking and solar become a consideration.
  • With an adequate solar system you’ll have no generator time unless air conditioning is needed. The TV will work fine with a 200 to 300 watt cigarette plug-in PSW inverter. Coffee makers pull more juice.

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