DC to AC help

[kfp673]

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

[theoldwizard1]

kfp673 wrote:
When I search, most of the inverters have AC plugs directly on them but I would like ours hard wired in.

While common, this is not universal. Samlex makes inverters that are designed to be hardwired so that all AC outlets will work.

If this is what you desire, I suggest you buy an inverter/ charger/automatic transfer switch. Get rid of your old converter any wire the new inverter/charger/automatic transfer switch directly to your batteries via a mega-fuse on the positive cable and a meter shunt on the negative cable!
Your shore power cable goes directly to the inverter/charger.

[Acampingwewillg]

Can't speak to the quality but Newpowa has a sale going on right now.....1200 watt inverter with remote- 159.00 and I think their 2000 watt with remote is 179.00 both Pure Sine wave. I don't think either have a transfer switch but seems like good prices. I was only checking it out due to a solar panel sale and I was looking for a stand alone inverter for my residential fridge.

[padredw]

Valhalla wrote:
If you try to automate it, you need to have a way to disconnect the charger. Otherwise, it will draw battery power to run the inverter, which will run the battery charger, to charge the batteries and the cycle continues.

This is absolutely true, but I used a very simple approach. There are two switches side by side inside my coach: one to turn the inverter on and the other to turn the converter off. I know this is not 100% fail proof, but in practice I find that it works well for me because anytime I turn the inverter on, the switch for the converter is right there beside it.

[BurbMan]

I agree with your approach and what you are looking for is a transfer switch. In rigs with generators, the transfer switch automatically powers the rig from with either shore power or genset.

I chose not to light up the whole rig from my inverter and used a single circuit 15 amp transfer switch instead. I have a 600W inverter and selected the circuit that I would want powered from the inverter. The transfer switch is hardwired into the breaker panel and connected to that circuit, so only the outlets on that circuit receive power when the inverter is powered.

Here is the inverter and transfer switch set up


The Xantrax has a remote option so I mounted the remote in the trailer by the other controls, along with a voltage meter:

[jdc1]

So, wouldn't putting a manual shut off just before or after the converter breaker be an ideal/safe way to power up all the RV outlets? A nice little 30A AC switch with a HUGE sign reminding you to shut it off when unneeded?

[valhalla360]

A stand alone unit is a lot easier to install (even if hard wired).

If you try to automate it, you need to have a way to disconnect the charger. Otherwise, it will draw battery power to run the inverter, which will run the battery charger, to charge the batteries and the cycle continues...unless you have come up with a perpetual motion machine, there will be losses all along the way and it will quickly deplete the battery bank.

You can kill the charger breaker manually but expect at some point to forget and wake up with a dead battery bank.

Keep in mind, AC loads are often higher wattage, so your pair of 6v golf cart batteries may not be up to the task.

[2oldman]

Probably should be in tech issues

[padredw]

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.]

[CA_Traveler]

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.

[Lwiddis]

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.