Automatic Transfer Switch

pianotuna wrote:

Gdetrailer wrote:

Otherwise, if it is you simply do not like propane at all, swap the RV fridge for a home fridge conversion.. My current TT, we did a home fridge conversion, just one pair of 6V GC2 batteries powers everything we use including the fridge for 24hrs without the need for solar or a generator..

Gdetrailer,

Do you know the make and model of the fridge?

Haier 10 cu ft fridge, marketed as small apartment size, same manufacturer that makes Magic Chef and a few other well known brand names of that size.

I measured the current draw personally and average was right at 90W at 120V, compressor is marked as 1.1A draw.

Only downside to it is it is a frost free model so it does have a auto defrost cycle but that only happens once for 10 minutes for every 10 hrs of compressor operation. My timed tests gave average of 20-22 minutes compressor run per every hr from 50F all the way to 100F. Didn't bother testing below 50F as I am not a colder weather camper.

Paired that up with a Tripplite PV1250 MSW inverter which has a power save feature which puts the inverter into a deep low power sleep mode when it does not see a 120V AC load. That power save mode saves 24 Ahrs of battery capacity alone per 24hrs.

Since the fridge is pretty efficient the charge line from my vehicle is able to nearly support the fridge while driving unlike if I was attempting to run a absorbsion fridge off of 12V.

Gdetrailer,

Nice choice of inverter/fridge. My Magnum has a standby mode--but ever few seconds it checks for a load. That causes the microwave to beep, as I run in a "whole house" mode.

TechWriter wrote:

So OP will have to always remember to throw several switches or risk dead batteries.

Plus, if the ATS is generator preferred and the inverter is connected to the generator side of the ATS, then OP will have to remember to also turn off the inverter when shore power is applied.

Why not just use a manual transfer switch?

Or, though more expensive, it sounds eminently more practical to buy an inverter/charger with a built-in transfer switch and wire it like so (with or without a sub panel), especially is OP's wife or friend(s) will also be responsible for switch throwing:

no he won't nothing poweres up just because the breaker box is live.

the whole idea of using a transfer switch with an inverter is for boon docking so you do not use them at the same time and you turn it on when you need it. I have left mine running for an entire weekend but didn't use any 120V stuff and I used a whopping 5AH more per day due to the effiency of the inverter. now if you have your frifge on electric and such then ya you need more batteries than the four I have. when I plug in shore power with my inverter running it will actualy disconect my inverter and reansfter to the shore supply so that is how the factoy wires it when you don't have a genny.

Steve

pianotuna wrote:
Gdetrailer,

Nice choice of inverter/fridge. My Magnum has a standby mode--but ever few seconds it checks for a load. That causes the microwave to beep, as I run in a "whole house" mode.

Yes, the Tripplite does similar thing as your Magnum, it sends a quick pulse every few seconds in order to detect if there is a 120V load above my preset. Set mine to power on if it sees about 9W, this way I can plug in a 120V trouble light and it will turn on the inverter if I need the light.

I don't bother with MW on inverter, figure for that it doesn't take much effort to start the gen so to me it was a low priority item.

Since you don't need the microwave powered all the time, add a manual switch in a easy to get to location, switch the microwave off when not needed.. That would allow you to take advantage of the low power sleep mode you have.

I use a 20A DPDT toggle with center off to manually select shore or inverter for my Home fridge conversion. Saves plugging and unplugging.

Have been considering upgrading to the Tripplite APS versions which have built in ATS for the fridge which would simplify our setup and teardown list of things to do.

Some inverters, Victron, for instance, will pass thru the full amount of shore power and even synchronize the phasing so if shore drops off, the inverter takes over instantly "no break power transfer" as McDonnell Douglas called it on the MD-11. No need for a transfer switch at all.

Charles

All valid points.

As far as cost of this Mod goes it's actually pretty cheap compared to some of the mods I have done about $200.

If my current fridge draws too much power to run when towing with the solar I now have then so be it I will go back to Propane I simply want the option of energizing my outlets from the inside of the trailer with a flick of a switch.

If my refrigerator failed I would consider a residential fridge although I do like to use of propane when boondocking so that would be a hard choice.

At around $1400 that is an expensive option. As with a Victron inverter/charger running about the same price.

A question regarding wiring.

Most of my parts have come in and I am getting ready to wire. Not sure if the ATS will fit in the same cabinet behind the control panel. If it does it would be great as wiring would be shorter and easier. If not I will have to Put the ATS is a cabinet where the Park cable extension cord coils up.

This would add about 15 extra feet to my wire run. From the ATS I will need to run wire to the Inverter about 20 feet. I will also have to run wire from the ATS to the Converter Charger as it has to be wired to the ATS a distance of about 15 feet.

I'm planning on running 10 gauge wire. Should I use stranded 10 gauge wire (more expensive) OR a 10/3 Romex? The Wire will be routed out the floor and along the frame to their termination points. Either one will be inside flexible plastic conduit.

Any thoughts?

Here's a schematic of my solution:

K1 is my existing ATS. K2 is a 120 VAC 30 amp relay. The output feeds all my 120 volt receptacles except the ones feeding my fridge and microwave. The converter is powered only when on shore or generator power.

1L243 wrote:


I'm planning on running 10 gauge wire. Should I use stranded 10 gauge wire (more expensive) OR a 10/3 Romex? The Wire will be routed out the floor and along the frame to their termination points. Either one will be inside flexible plastic conduit.

Any thoughts?

Either stranded or solid wire is fine, Romex is not really rated for use inside conduit. "Single strand" stranded or solid building wire unlike Romex should be run in a conduit.

In the past, I was able to buy single strand at a lower cost per ft because of bulk pricing but when you add in the cost of conduit actually made it more expensive option than Romex. If the wiring is exposed to potential damage hazards then conduit might be better option over Romex.

Automatic Transfer Switch is installed. As usual the estimated cost of $200 was more like $300. Primarily due to the cost of shielded 10ga copper cable.

I needed about 42 feet.The distance from the control panel to the ATS which is in the front pass through is about 13 feet. I had to run one 10ga cable from the control panel to the panel side of the ATS. A second cable from control panel to the Plug side of the ATS and a third cable from the Progressive Dynamics converter/charger (which is located below the control panel) to the Plug side of the ATS. A fourth cable from the Inverter to the Inverter or Generator side of the ATS. This distance was only about 2 feet.

Since I no longer need the the 15 amp dedicated breaker in the service panel for the Converter/Charger I added a 15 amp AGC fuse inside the ATS to protect the Charger.

How it works.

When plugged into shore power everything works as it should. When I want to run on the Inverter generally I will already be unplugged from Shore power. But, if not the Inverter will have priority . The batteries will only charge when plugged into shore power.

From inside the trailer I turn on the Inverter using the wired  remote on/off switch. There is a 35 second delay. You can hear the ATS "click" and then everything comes to life inside the trailer.

I won't know till the next time I take it out on a sunny day when I have solar to see if turning on the refrigerator if I will be in the positive or negative.

Regardless it will be nice to have shore power at the flick of a switch wherever I am.