POWER INVERTER? CONVERTER? ?

No offense, question sounds familiar indeed.

You want inverter 1.5 times more than total nameplate(s) of everything that you will be running at the same time. Get inverter without fan if you mount it where you can hear it.

Bigger inverter won't draw more watts than the load demands, but it will draw more if you leave it on when not in use. The bigger inverter - the higher idle draw. For this reason you don't want to have it much bigger than you need, and it would be nice to turn it off when not in use. Small inverters rarely come with remote switch, and if mounted in living quarters for ease of switching it on/off, you want a fan-less model.

Thank you all. I now know what I need. Yes, this is almost a repeat of a previous inquiry but not quite. Thanks to all for your willingness to help. Much apreciated

My last 2 TT's were mostly DC powered for everything except the microwave and Air Conditioner so I only used a 400 Watt pure sine inverter in the bedroom primarily to power my ASV type bipap machine. It worked fine even if I chose to run the humidifier. It's a 28vdc machine and I never bothered to get a DC adapter for it as I already had the inverter. The Bipap I had prior to this one worked on 12vdc so I just direct plugged it into a DC plug I installed in the bedroom.

I wired a 600 Watt Pure sine inverter into my current 5er auto transfer switched to power the whole trailer. I currently have to remember to turn off the circuit breaker for the DC converter before I turn the inverter on, but will wire in a relay to automatically isolate that circuit when it gets cool enough I feel like crawling into the equipment bay area. I also switch the fridge to gas and the water heater as well. My 600 watt inverter powers the TV's, microwave vent fan if needed, my powered recliners etc but isn't big enough for the microwave, AC, or any heating items bigger than our crock pot. It also powers my Bipap through the night no problems.

You might want to check out the AIMS 600 Watt Pure Sine 12 Volt Power Inverter - PWRI60012S that is on AMAZON for $122 I think I saw. I paid more than that back in 2009 when I got mine... After I burned up a couple of item with my Modified Power Inverter I just stopped using them altogether... Think I still have one I use for my outside lights in an emergency...

This is a full 600WATT PSW model which is available from each 120VAC receptacles.
i.e. you can pull 400WATTS for your CPAP machine from one of the 120VAC outlets...

I use this 600WATT model directly connected to my battery bank and it is usually ON all the time we are camping. I ran one HD multi-head Extension cord to the home entertainment area of my POPUP and a second HD multi-head Extension cord back to the table near our tent bed.

This provides me with all the 'emergency power' I need for my electronics and other items. I usually only use around 250-300WATTS from the POWER INVERTER mainly from 6PM to around 11PM in the evenings running the Home Entertainment HDTV and my ham Radio things... My battery drain measured at the main Battery Switch is usually around 20AMPS DC current during this time period. I have some thing direct wired to the 12VDc Distribution panel.

This usually drops my 255AH battery bank down to its 50% charge state by 8Am the next morning when I am allowed to run my 2KW generator to charge my battery banl bank back up to its 90% charge state. this takes around three hours of generator run time. Then I am good to go again for the next day/nigh run off my batteries.

I watch my battery drain on and inside DC VOLTMETER setup and when it drops down to around 12.0VDC I know it is getting close to the 50% charge state.

This is what I have been doing since around 2009 with my off road POPUP trailer running off my battery bank...

Hoping my story hasn't changed much since last you asked haha...

Roy Ken

What do you have for batteries?

Oasisbob wrote:
My current 400 watt modified wave unit duns electronics okay but will not run Cpap machine or box fan so I am told I need a pure sine wave unit. So what size unit would you suggest to run the above equipment? If I get a larger unit than what I need will it use more power even if I don't reach max capacity? I really am ignorant on this and Youtube video's have not really told me much. Any thoughts?

You have left us ignorant also. :B In order to make a suggestion we need to know the watt rating of the CPAP and fan.

My CPAP runs on my MSW inverter. Draws about 80 watts.

An oversized inverter will only draw slightly more than just big enough.

If you are only needing it to run the CPAP, I'd get one one 1.5 times the required wattage. That would be 600 watts if your CPAP requires 400 watts. Several 600 watt and under PSW inverters can be found here.

Get a PSW that is 125% larger than the highest wattage device you wish to run.

There will be idle current losses, but if you have a 600 watt inverter and only draw 400 watts the demands from the battery bank will be at the 400 watt level, not at the 600.