Adding Interior 110 outlet from Solar

[sbair]

I have an '04 Bambi (19) that has an 80w Go Power Solar charging kit installed. We do a lot of dry camping and because the outlets don't work when we are "dry", I would like to add an outlet that we can plug small things into. I know I'll need an power inverter however, I don't know how to put it all together. I believe I would add the outlet on the front left side, under the table bench seat (where the water holding tank it).
Thanks for your thoughts.

[jdalrymple]

The most efficient setup would be to place the inverter as close to the battery as possible and then run the 120 volt AC wire to the most convenient location for use.
Converting 12 volt DC to 120 volt AC is not very efficient process. It takes a LOT of 12 current (amps) to make 120 volt AC power. The longer the distance between the battery and the inverter, the larger the wire must be to carry the high amperage current. But, a light 14 gauge extension cord will carry the 120 AC power anywhere in your trailer with very little loss.

[DreamStreamr]

We recently added a 400 watt inverter specifically to run a desk lamp we picked up for our dinette. It looks so great, what we had been looking for. Has a CFL 9 watt bulb, so doesn't use much juice. And we have 460 ah battery storage, lots of capacity. But we didn't have an inverter.

This was a cheapy inverter but is quiet and fits no problem near our battery banks, under our L-sofa. We plugged a short extension cord into it for the lamp. We plugged into the inverter also a switched outlet strip mounted on the back of the dinette backrest just under the magazine racks, facing the sofa. We installed a remote on-off switch for the inverter.

We use the inverter to power the lamp, of course, and the outlet strip provides all the outlets we need for charging two laptops, a phone, a tablet, all at once if we want.

Someday we might get a big boy inverter to do the "house". It would be a much bigger step, though, because we would then need an automatic transfer switch, disaster fuse, added distribution panel, and much bigger primary wires. Whenever we discuss it we readily agree, we don't need anything more than the convenience outlets from the current setup.

[CA_Tallguy]

Yes, as has already been said -- put the inverter very close to the batteries, and keep the wiring very short. Also, you MUST use heavy gauge wire to the inverter as the current draw will heat things up. For a small inverter that will not run much, it isn't as big of a concern as a 2000+ watt inverter, but still -- you very much need to use decent cable.

It would be best to have the inverter close but separated from the batteries, however, as an inverter can generate small sparks and batteries can put off flammable gas.

Finally, you might want to get a decent quality inverter, if for no other reason than a good one won't need a fan running as often! I just picked up a 600 watt xantrex prowatt SW (sinewave) inverter for about $100 on clearance at Camping World. I think the employees marked it down more than they were supposed to. Still, looks like they are only $150 to $200 on the web. Very nice unit and the fan hardly runs compared to the inverter I previously had. I actually don't think it has run at all with the loads that I've put on it (TV+DVD, computer, cordless tool battery chargers).

Here's an informercial-ly video about it...

Gear to Get w/ Brian Brawdy - Xantrex PROwatt SW Inverter Series - YouTube

If you don't know about inverters -- the sinewave inverters are "clean" power and you don't have to worry about incompatibility or damage to certain electronics. The "square wave" inverters run just about everything but still -- to save 50 or 100 bucks they are not worth the risk to me. If I get a very large inverter, I might think about a square wave if I also still have this sinewave for sensitive things.

OK, one last bit of advice -- buy an inverter that isn't oversized for what you think you will need. They run more efficiently when matched to the load, or so I've been told.

[DreamStreamr]

Man, I want the sine wave inverter you got, CA Tall Man. Great deal and much better setup than I bought. We weren't really looking for more than a pocket inverter to run the lamp so we under-spec'd it trying to get by.

Then we realized, Hey, this is a cool thing to have -- so we rigged it for more convenience. I'll be following your advice on (1) getting a better quality one, preferably SW; and (2) gaining a quieter one, although we barely hear it under the sofa.

Thanks for great post!

[CA_Tallguy]

I forgot to mention one thing about mounting location -- you need to think about turning it on and off as it will draw current even if items plugged in are not powered up. So it should be accessible for that. The xantrex units have a remote panel you can buy but I'm not 100% certain that you can turn it on and off from them so best to check that out first. Somewhere I read that safety regulations made it so you could only turn OFF the inverter from the remote but to turn it on you had to do it right on the inverter. Seems too bad if that were the case so I do hope that I am wrong and they work for on AND off.

My inverter is in the credenza next to the fridge so I can reach it no problem, but I have HUGE welding cable running there from the batteries because that's where my solar controller also is located.

Another way to wire it would be with a switch (high current or using a high current relay) on the 12 volt feeding the inverter, but again you need to make sure that the inverter would switch on and off using that method. I think many use electronic switches that start up in the OFF position when power is applied. So this method may not work on any inverters at all. Can't say for sure.

[idroba]

Just a couple of more things on the Sine Wave vs. the Modified Square Wave type inverters.

The SW typically have a higher standby loss (that is current draw when at idle, not powering anything). Typical is 1 to 1.25 amps. Standby losses on most Modified Square wave inverters is in the range of 0.06 to 0.1 amps. Some go as high as 0.6 amps. So, if you leave the SW on when not using it, it will eat into your batteries at a much faster rate.

The overall efficiency of the SW inverters is somewhat less than a MSW inverter, partly due to the factor above. SW generally in the 85% to 88% and MSW in the range of 90% to 92%.

I am not pushing one over the other, but I did want to point that information out.

[DreamStreamr]

Spot On about the switching circuit.

I used a too small relay first time, and the inverter can reclose the relay contacts on it's own -- not a good thing. I am installing a 50amp 12vdc relay instead of the original 30amp relay. Nice thing about using a high current relay is using a very small current circuit for switching. I have a micro-switch mounted next to the ham radio, easy to reach and use.