Adding Second Inverter

[mlr1951]

I want to install a residental refrigerator and a second inverter. I want the refrigerator to switch from inverter to shore or generator power when available. What is the correct way to do this?

Thanks

Mike

[rossboyer]

Usually, at least with our Xantrex inverter, when shore power is available even though the inverter is in the Invert mode; the inverter is bypassed to feed the attached circuits from shore power. What size inverter is currently installed in your motor home? Possibly it is big enough to handle the residential refrigerator. If it isn't, the battery bank is usually sized to handle the expected load; and you may need to add another battery bank or upgrade the capacity of your current battery bank. On our motor home, the inverter has 2 circuits of 20 amp each. When our refrigerator fails, I am going to install a switch or relay to enable switching between the microwave and refrigerator if using the inverter without shore power. Motor homes differ, and you may or may not be able to do this.

[wolfe10]

Actually, TWO questions about your present inverter: Does it have enough capacity and is it a sine wave or modified sine wave inverter. Many residential refrigerators are not happy with MSW inverters.

And, as Ross said, many inverters have built in transfer switches. You should either choose one of them or figure on adding another ATS to the system if you want the transfer automatic.

Brett

[kenk02]

I assume your primary inverter has a battery charger. You want your second inverter to have an internal transfer switch (so it will detect no shore power and switch to "invert" mode). But you do not want an inverter with a battery charger. Two battery chargers may not "play" well together.

Xanterx Pro Series fills this requirement. Its available in 1000 and 1800 watt versions - 1000 watts is plenty for modern refrigerators.

See: http://www.xantrex.c...-inverters.aspx

ken

[desertdeals69]

If you list what ATS and Inverter you have by model I can tell you what you need to make the installation. We do this type of thing on a routine basis in our shop.

[mlr1951]

Thanks for the replys. This is a 2000 Mountain Air DP with a 2500 watt Xantrex Freedom 458 inverter/charger and 4 house batteries and a Power Switch ATS. The new refrigerator will be a no frills Frigidaire 10 CU/FT without an icemaker.

[desertdeals69]

The inverter you have is a modified sine wave. It could present problems with not only the refrigerator but some of the new electronics such as tvs. Size wise thats ok but I would have six batteries for more capacity. What would be Ideal is a 2500-3000 watt true sine wave inverter with six matched golf cart batteries.

[wolfe10]

The inverter you have is a modified sine wave. It could present problems with not only the refrigerator but some of the new electronics such as tvs. Size wise thats ok but I would have six batteries for more capacity. What would be Ideal is a 2500-3000 watt true sine wave inverter with six matched golf cart batteries.

I agree.

Brett

[RVerOnTheMove]

Thanks for the replys. This is a 2000 Mountain Air DP with a 2500 watt Xantrex Freedom 458 inverter/charger and 4 house batteries and a Power Switch ATS. The new refrigerator will be a no frills Frigidaire 10 CU/FT without an icemaker.

I have the exact same setup (but with more batteries) and I have run my household fridge (a 20CF GE Profile w/ ice maker) for over 10 years without issue. I would not change anything or add another inverter. You just need to add more batteries and rig the plug for the fridge into your existing inverter circuit. You should not have any further issues. The charger in your 458 will be able to recharge the additional batteries as well. I currently have 4 12V batteries providing about 1000 AH's and the 458 keeps them up just fine.

[mlr1951]

Thanks everyone for the replys and opinions. The TV is a new one and works fine with the modified sine wave so I will use what I have and move the refrigerator to the inverter panel.

Mike

[desertdeals69]

Keep in mind that as far as the modified sine wave inverter is concerned the effects could show up as shortened life of the electronics etc.

[RVerOnTheMove]

Or not. My coach has used the same 458 MSW inverter for about 10 years with no ill effects of any kind on any kind of electronics other than the plugged in clocks which won't keep proper time (I use mostly battery powered clocks).

I have a 20CF HH fridge, satellite TV, LED TV's, satellite internet modem and router, computers, phones, electric razor and toothbrush. What have I missed?

I do believe my MW oven would work better on a PSW inverter but I don't run the MW on the inverter anyway.

If I ever have to replace my inverter I will replace it with a PSW inverter, but I will never replace my working MSW inverter.

[desertdeals69]

I will keep my fingers crossed for you!!

[RVerOnTheMove]

PM

I will keep my fingers crossed for you!!

For me? You are thinking that maybe after having run all of this equipment in this coach with this inverter for the last 10 years something might suddenly go wrong tomorrow?

I know there is disagree with about the use of MSW inverters with modern electronics, but I am posting actual experience with actual hardware.

[desertdeals69]

We have been in the RV business for 36 years and have encountered quite a few different situations along these lines. I'm just passing along what I've learned along the way. I was using inverters back in th 70's when most of the rvers didn't know what one did. They didn't have battery chargers so we had to make high amp chargers to shorten the charge time while running on the generator.

[RVerOnTheMove]

You might have the best knowledge of anyone I know about the equipment from the 70's. You may or may not be aware of this, but the hardware in almost all the RV's today is newer and more sophisticated equipment (like the 458 MSW inverter) than what was installed back then. I hope this does not come as a surprise to you, but what I stated was real world experiences with "todays" hardware. I have seen many posts by many folks that the MSW inverters can cause major issues and should be avoided. I have yet to see one single poster back that information up with facts (lots of opinions, but no facts).

[desertdeals69]

The Inverter that you have was designed some 20 years ago not hardly what is currently the best today. I agree with you that some folks can and do use older equipment and it works just fine for them. This discussion started out as to what would be needed to make what he had work the best. I offered up what we have found is the optimal set up.

TV's that failed with MSW inverters first cropped up when the flat screen plasma came on the scene. The LED/LCD TV's are relatively new so we don't have that much history with them. Other things that failed were micro processors in coffee makers and microwave ovens.

[wolfe10]

Guess I'll weigh in on this one-- I think this thread has gone about as far as it can.

If you need a new inverter and you can afford a true sine wave inverter GET IT.

Can a MSW inverter successfully power your new refrigerator? Best advice-- call the refrigerator manufacturer for their advice.

Everyone-- have a great Thanksgiving holiday.

Brett

[RVerOnTheMove]

I agree Brett. If (IF) he needed a new inverter he should install a PSW. Since his inverter is working perfectly well he has different decision to make.