Inverter for your Solar Vintage

[Zeppelinium]

I'm not a fan of inverters. IMHO, you should never use them to power a microwave or hair dryer or any other high power 115v device. However, if you have a good solar setup, you still need 115v now and then for things like charging your laptop, electric razors, maybe an outside string light, or an LCD TV that plugs directly into mains (all of these are less than 100W).

My converter and fuse block are mounted on the shell inside the "closet" in the bathroom. This makes for a very convenient location, especially because the outside 115V receptacle is available under a cover in that same area. The inverter is connected to the battery through the fuse block with its own 10A fuse (even though it's a 400W inverter, I want to limit the draw on the battery to less than 120W).

The inverter is connected to one of the sockets the outside receptacle, so I have inverter power available inside (one socket on the inverter) and outside. CAUTION: The inverter doesn't really have a neutral. You can't connect the trailer neutral to what you think is the inverter neutral or you will blow the fuse (some converters may not have this problem), so you have to break BOTH of the tabs on the receptacle so the socket connected to the inverter is totally isolated. The inverter ground, on the other hand, can be connected to the shell/trailer ground system.

Now I can go totally solar and still watch our small TV and charge the laptops (using an extension cord). And I can plug in our LED string light outside. Yay!



Zep

PS: Most gadgets these days can be charged with 12V or USB 5V, both of which can be derived directly from the 12V battery buss. The only thing you have to be aware of is that some 12V devices treat 12V as their max and, as you may be aware, the charging voltage on a lead acid battery can be as much as 14.4V. So be careful connecting your 12V electronic gear directly to the "12V" system in the Airstream.

PPS: I cannot spell "receptacle".

[kidjedi]

There is a "luxury" in rebuilding an Airstream that isn't as easily available to finished trailers because of the difficulty in accessing the lines. I am pointing this out for those doing restoration or renovations that allow for re-doing the wiring. I have taken to running a 120v line to the microwave/toaster, central vacuum, and bathroom that can only be powered by shore connection (these three lines bypass the inverter and I use orange hospital grade outlets for these sockets). The rest of the 120v outlets are run to the inverter, and can be powered by shore *or* battery/inverter. I also install panels with 1 or 2 "cigarette lighter" outlets to accommodate the ubiquitous automobile connectors as well as several 5.5mm female panel mount sockets. I've found that the 5.5mm outlets are the most common for 12v devices, and I simply re-wire anything with a different size to a 5.5mm male pigtail. This has worked very well, and helps mitigate worry about power sources when boondocking.

[Zeppelinium]

Originally Posted by kidjedi

...The rest of the 120v outlets are run to the inverter, and can be powered by shore *or* battery/inverter.

OK, the problem with powering a 120V circuit with both shore and inverter is that you need a transfer relay, which is expensive*. Am I wrong about that? Or does an inverter sync up with the shore power, much like a mechanical generator?

I agree with your 5.5mm sockets. Good move.

Zep

* you can make one with a simple relay if you are willing to let the inverter be in charge of the relay. Circuit provided on request.

[kidjedi]

Originally Posted by Zeppelinium

OK, the problem with powering a 120V circuit with both shore and inverter is that you need a transfer relay, which is expensive*. Am I wrong about that? Or does an inverter sync up with the shore power, much like a mechanical generator?

Obviously you'd need to check your specific inverter, but I think most inverters these days have a pass through feature that only utilizes the inverter when there is no 120v source. In other words, when the AS is on shore power, the inverter just passes the current through. When the AS has no current from shore power, it uses the inverter to convert 12v DC to 120v AC. Again, be sure to check your specific inverter to verify this.