How do I wire in an inverter

bigrigfixer wrote:
To only power the microwave, the outdoor kitchen fridge, and the outlet beside the bed for a cpap?

"Only" a MW oven, compressor fridge, and CPAP? :h Not expecting much from a 12 vdc system are we?! :E

I wouldn't be worried about it normally, but our new trailer has the outdoor kitchen with a fridge that runs on 110, and it would be a shame to only be able to use it on shore power.

Power requirements for these dorm style fridges obviously varies but I'd bet yours is rated at least for 200 watts, if not more ... 200 watts / a nominal 12 vdc = ~ 16 amps, not even accounting for inverter loss. That's a heck of a load on the battery just for the convenience and IMO unnecessary when you already have a gas absorption fridge designed specifically to run with minimal battery draw. :E

So then I thought about putting in the inverter, and remembered reading about splitting the control panel. So then I figured it would be nice to have a microwave, and while we're at it, have the cpap working too.

"Nice" to have? :h Wow, that "nice to have" your MW oven running is by definition going to require a substantial inverter, probably at least 2000 watts, a substantial battery bank, probably dual 6 volt batteries if not 4 running series / parallel, and some method - solar or generator - to properly maintain those batteries. Since any solar system suited for this task would also have to be substantial that then raises the question as to why you wouldn't just invest in 2K genset such as a Honda EU2000i or Yamaha EF2000iS that can power anything in your rig other than A/C but including your MW oven AND recharge whatever battery you have, as needed, regardless of whether it's sunny or not. I can see where running a CPAP on battery power may be necessary when dry camping but a MW oven will only unnecessarily suck the life out of any battery. :E

On our last trailer, I installed a 12 volt outlet for the cpap to plug into with a manufacturer supplied adapter. I may still go that way...

If this worked for you before then there's no reason it shouldn't work for you with your current rig ... K.I.S.S. ;)

But after searching all night, I can't seem to find the post of who and how splitting the panel was done.

There's no need to "split" anything, especially if you're going to invest in a substantially sized inverter capable of running a MW oven. Simply install it as close to the battery bank as you can using appropriately sized cables and plug the trailer's main service cable into the inverter's 120 vac output. This "whole house" scheme means the trailer will behave just as it would when plugged into shore power, of course within the limits of the inverter and the battery bank powering it. That said, I still see a 2K inverter genset as your best overall solution for what you say you expect to power when you don't have 120 vac shore power available.

Hi,

So what are you asking?

There are basically 5 wires going to a built in inverter.

Battery + 12 volts
Battery - 12 volts

120 volts from the circuit breaker if it has a pass through relay
120 volts out to whatever receptacles you want to power
120 volt neutral wire
Green ground is also normally installed to. One wire to the ground bussbar on the circuit breaker panel, and perhaps another wire to the RV chassis.

If the inverter does not have a built in transfer switch, then you can install one. It will have a 120 volt coil on the 'gen' side of the input line. Once the transfer switch sees 120 volts from the GEN it will delay for an adjustable time (usually 0 seconds or 30 seconds). In your case, you would hook up shore power to the 'gen' input, and set the time delay to 0 seconds. Then hook up the non-powered relay connection (normally labeled shore power) to the inverter output. This will not consume any extra battery power to run the transfer switch.

The transfer switch output then goes to the circuit breaker panel, and to the receptacles that you want to power (but do NOT connect the output to any circuit beakers, only the black wire going to the microwave receptacles or rear refrigerator receptacle. Also make SURE that you do not power up the battery charger/converter with the inverter output wires.

What I did with my motorhome was remove the wire going to the TV set from CB #3. Then I connected the black wire to the inverter input (it has a transfer switch and charger built in) to CB #3. The wire removed from CB#3 went to the inverter output. I also connected a white wire from the neutral wire from the circuit breaker panel to the inverter.

Two more #000 wires from the bank of 4 batteries to the inverter, and I was done. I also installed a remote control panel to turn it on and off from inside, as well as a temperature sensor for the battery to limit charge rate when the battery is hot.

Good luck,

Fred.

There are many ways to do this depending on many things you have not mentioned such as battery bank size, coach size/type and how convenient you want to be able to operate things.

Typically, inverters are installed with large cable going to battery banks that are very close nearby. Portable inverters with cigarette lighter plugs are up to 300 watts but usually 150 watts or less. The 300 watt inverters would require the cigarette lighter wiring going to the source to be at least #10 wire and most RV do not use that large of wire.

A microwave would require a 2000 watt inverter in most cases. Two group 27 batteries would be the bare minimum and would provide only a short amount of run time while leaving enough battery power for other things.

There are two kinds of inverters. Stand alone and in-line, the In-line type also charge batteries.

Stand along: Battery-Inverter (note very short cable there---long line--- Oulet(s) near what you wish to power (make 'em orange or red) move plugs to use inverter and turn it on.

In-Line this is for a 2000 watt model larger or smaller you may need to change breaker size

Main power panel--30 amp branch---inverter---Sub panel (15 amp breakers note some inverters the sub panel is built in)====Loads

Also 12 volt (very short leads)to inverter/battery

NOTE on the 12 volt leads

the invewrter install manual will recommend a size for any given run,, UPGRADE at least one size.. and tape the two wires side by side for most of the distance (As long as you can) This will improve inverter life.

Install a sub panel. Put a transfer switch between that and the oem panel. Move the circuits you wish to power to the sub panel.

I prefer to power all the outlets so I simply plug the shore power cord into the inverter. My default for the OEM converter is disconnected and water heater is off. That leaves only the fridge to move to propane.

I wouldn't bother with the microwave - it requires too many amps to run even if for a short time.

It would be more efficient, energy-wise, to continue to run the CPAP on 12V. You don't waste power on the conversion.

I would get a small inverter to power only the fridge.

Running a microwave on a battery/inverter is going to be challenging without a huge battery bank - this was discussed in detail a couple of weeks ago.

If you want to power only certain circuit off the inverter, then go to your fuse panel and switch OFF those circuits you don't want powered. Then plug your main shore power plug into the inverter which is the connected to the battery (as close as possible).

Gerry