Xantrex inverter in Class A- again

Hi all, after a lot of research here and elsewhere, I've decided to install a Xantrex modified sine wave inverter in a 1997 Itasca Suncruiser 32WQ (I can get by without true sine). Originally I was going to do the Xpower 3000 and hard wire it to the panel. I've also been kicking around the 1750 which doesn't have the hard wire capability. Here's my questions:

1) I plan to run only a TV/DVD player, propane furnace, fridge, and occasional micowave while driving, and only the furnace and maybe a fan while stopped with the engine off (winter trip coming up). Should the 1750 be big enough, or go with the 3000 just to be on the safe side? I have a big problem with always having to have "more power" even when it's overkill, so I'm trying to be responsible and not overdo it.  ;D

2) I'm installing it in the same basement compartment as the transfer switch. Instead of hard wiring it to the panel, can't I just use my 30A shore power cord and 15A adapter like I do to plug it in at home, and just plug it directly into the inverter receptacle, and use the inverter remote on/off switch when I want to use it? I should be able to go up to 1800W without overloading that outlet (15A X 120V).

3) If I just plug in the cord as above, that also runs the converter/charger. How will that do with it recharging the house batteries at the same time it's drawing from them?

I have no problem hard wiring it to the panel if needed, but the 1750 doesn't allow it, and if I can get by without it on the 3000, it would make it easier to remove in the future if I desired.

Plugging the shore power cord into the inverter will work.  I have a 1750 watt inverter in my Arctic Fox that I connect that way.  But you have to turn off the converter when you're using the inverter or you'll set up a perpetual motion loop from the batteries, through the inverter, to the converter and back to the batteries.  Since each conversion step is less than 100% efficient this will  waste a lot of battery power.

The easiest way to break the loop is to disconnect the converter from it's AC feed.  If it plugs into a wall socket, unplug it.  Or install a switch on it's AC feed or turn off the circuit breaker that feeds it.

You might also look at other parasitic loads on the AC side.  For example, the circuitry that interfaces a wall thermostat to the air conditioner will increase the inverter's battery draw by about 1/2 amp.  So I turn off the air conditioner's circuit breaker when I plug into the inverter.  This does not affect the operation of the furnace, just the air conditioning which won't work on the inverter anyway.

The 1750 should be large enough for anything you want to power.  The largest restriction on how much power you can use will be set by the amount of current your batteries can supply and the size and length of the 12 volt wiring between the batteries and inverter.    You'll be drawing about 175 amps from the batteries to provide 1750 watts output from the inverter.  This means you'll need at least 400 amp-hours of battery storage (i.e. 2 pairs of 6 volt, 200 amp-hour golf batteries) to get 175 amps current flow out of them without unacceptable voltage loss.  Deep cycle batteries do not like to supply a lot of current all at once - they're designed for slower, deeper discharges.  Same thing with the DC wiring to the inverter - you need short, fat wires between the batteries and inverter.

Very concise and accurate information, Lou.  Good job.

I just wanted to add that I did install a 2500 watt Vector inverter in my Bounder using an additional transfer switch directly into the main panel.  The inverter documentation stated that it was not designed for hardwire installation but I simply fabricated a length of romex with a plug on one end (plugged into the inverter output receptacles) and attached the other end to the input of the transfer switch.  It just seemed easier this way since I needed ac at each end of the coach (front tv, laptop, and CPAP machine in the rear).  Works fine.....

The panel was easily split (removed an internal jumper) so that the A/C units and converter were only fed by shore or generator power.  My entire procedure now consists of turning the inverter ON or OFF.....

I did have to engineer my own remote on/off switch (wired like a house three way arrangement) complete with LEDs for power and alarm indicators.  lou long

I did the same as Onaquest with a previous coach - and I used an inexpensive off-brand 2 KW inverter as well. Liked the $200 price (they are even cheaper now) better than Xantrex' $1000 for the same function. Rigging a remote switch to the inverter's internal on/off switch was also easy - just a snip of the wire to the inverter's front panel switch and splice in the remote wiring.

And a transfer switch can be made with a household type double pole, double throw switch. Or a pair of single pole, double throw switches (a "three-way" light switch works).  Mount them in an electrical box of a convenient style and you are in business.

But it is perfectly OK to use it as you mentioned too - just unplug that converter like Lou says.  That's assuming your converter is the plug-in type - some are integrated with the AC/DC power distribution panel and it takes some re-engineering to turn off the converter.

Thanks for all the info. I'll have to check but I think my converter is integrated.

This is probably a really dumb question, but will my house lights still work with the converter disconnected? I know they're 12V but didn't know if they were donwstream of the converter or if they are also straight into the house batteries.

Thanks again, Kevin

All inverters over around 100-200 watts have direct wire capability

You want to put the inverter right close to the batteries... You need 1/10th the wire on the 120 volt side you need on the 12 volt side.  So if you put the inverter near the batteries you spend a whole lot less on cable to hook it up.

John In Detroit said:

All inverters over around 100-200 watts have direct wire capability

You want to put the inverter right close to the batteries... You need 1/10th the wire on the 120 volt side you need on the 12 volt side.  So if you put the inverter near the batteries you spend a whole lot less on cable to hook it up.

Click to expand...

The 1750 said it doesn't have direct wire capability where I reviewed it at. The 3000 had the knockout for it and said it could be. I think I will forgo the hard wire option and do the plug-in for now regardless. I'm going in a basement compartment on the opposite side of the coach from the batteries, but will still be within the 10' required in the Xantrex manual, and will actually be around 5' away just the same. Thanks for the input.

RV Roamer said:

I did the same as Onaquest with a previous coach - and I used an inexpensive off-brand 2 KW inverter as well. Liked the $200 price (they are even cheaper now) better than Xantrex' $1000 for the same function. Rigging a remote switch to the inverter's internal on/off switch was also easy - just a snip of the wire to the inverter's front panel switch and splice in the remote wiring.

And a transfer switch can be made with a household type double pole, double throw switch. Or a pair of single pole, double throw switches (a "three-way" light switch works).  Mount them in an electrical box of a convenient style and you are in business.

But it is perfectly OK to use it as you mentioned too - just unplug that converter like Lou says.  That's assuming your converter is the plug-in type - some are integrated with the AC/DC power distribution panel and it takes some re-engineering to turn off the converter.

Click to expand...

My converter can be unplugged, so looks like I'll be good to go. Just have to decide between the Xpower 1750 and the Xpower 3000. Still leaning towards the bigger one since my micro is 1545 Watts (even though that will be occasional) and would make the occasional bigger power need easier to do without turning off the other items, but I'll see. The 1750 can be purchased around $150 cheaper, so may go that route.

My house batteries are dual AC Delco ACDM24DC, about 1 year old. They each say 550CCA with 280A. Should that be suffiicient for the short term larger inverter draw while driving?

Thanks again, I appreciate all the input and help from everyone.

fyrmnk said:

The 1750 said it doesn't have direct wire capability where I reviewed it at. The 3000 had the knockout for it and said it could be. I think I will forgo the hard wire option and do the plug-in for now regardless. I'm going in a basement compartment on the opposite side of the coach from the batteries, but will still be within the 10' required in the Xantrex manual, and will actually be around 5' away just the same. Thanks for the input.

Click to expand...

Oh, sorry.. I was thinking on the 12 volt side, not the 120 volt side,  My mistake (I'm very used to dealing with folks who want to mount the inverter 20 feet from the battery..> BAD IDEA and thus never thought of the AC side)

Sorry.  You can still put a standard plug on the end of a length of 12/2 W/Ground Romex you know  Or 2 lengths if your rig is a 50 amp

Or the proper size wire with a dual plug adapter..... IF you can find a dual plug adapter that is (I have a dual 15 amp to single 30 amp adapter in my adapter box)

This is probably a really dumb question, but will my house lights still work with the converter disconnected? I know they're 12V but didn't know if they were donwstream of the converter or if they are also straight into the house batteries.

Click to expand...

Disconnecting the converter from it's source of 120 VAC is no different than not being plugged into shore power.  All of your lights, etc. will work just fine.

I wasn't able to find any hard specifications on your batteries, other than they are Group 24 Marine/Deep Cycle.  But judging from their Group 24 physical size, they will be marginal for a 1750 watt inverter at full power - most likely you will see a 120 volt voltage drop under heavy load, and they are definitely undersized for anything larger.,

Thanks for the information. I do have room in my battery compartment to go with larger house batteries, so if it comes to that, I'll do that as well. Most of my use will be while driving (with alternator support), and on shore power or generator when stopped. Thanks again all.