Modified/pure sine wave

road-runner wrote:
Just looked at a CPAP I have access to. The supply output is 24 volts at 3.75 amps. I'd guess there's a pretty wide range of power requirements with different machines.

My CPAP and dw's BIPAP are both 12 volt. They are both Phillips Respironics units, I guess it varies by brand because Phillips sells 12 volt cords that fit ours.

Replace the modified sine wave 1800 watt inverter with a pure sine wave and move forward.

You can not plug one into the other however you can install them electrically Side by Side Or you can replace the POS MSW with a quality 2KW True Sine Wave.

What is a "Modified Sine Wave" also called by some a Modified Square Wave?

Well.. I grew up on a farm. half dairy, half swine. Now the Swine side instead of opening the gate we had a set of stairs. Up and down, over the fence so we could just walk over. . The hogs could not climb the steps like a dog or cat so the fence was secure.

If you look at a MSW wave on a 'scope it looks EXCTLY like a side view of those steps.

The steps are one of 3 things I know of called Stile
The next is a fictional character also known as Citizen Blue
Before he became a citizen he was a slave. His master raised horses While looking at a pile of horse dung he noticed something. called it to his master's attention who promptly called the vet and the horse was easily cured. had blue not noticed it the horse may or may not have lived but it would have cost a lot more to save it. That pile of horse dung is the third thing and how Blue got his slave name.

So the wave form looks like a stile. (The steps) but well...it's dung.

Square waves contain the fundeemental frequency (60 HZ) plus the fundemental times the number of steps (often 3) and all either even or odd (i think Even but it's been a long long time since electronics 101/2) harmonics.. Very dirty.

A pure sine wave contains... The fundemental.. period (Sweet like Flute sound)

Just looked at a CPAP I have access to. The supply output is 24 volts at 3.75 amps. I'd guess there's a pretty wide range of power requirements with different machines.

wanderingaimlessly wrote:
Not knocking the prior post, but one other option may be running 12 volt DC straight to the machine. Many CPAP & BIPAP machines are actually run by 12 volt DC power. Check with the maker of your unit, a 12 volt power cord, that could be run straight to the battery may be available.

Usually if there is any distance, you want to use 120v for long runs and 12v for short runs because of voltage drop issues.

Not knocking the prior post, but one other option may be running 12 volt DC straight to the machine. Many CPAP & BIPAP machines are actually run by 12 volt DC power. Check with the maker of your unit, a 12 volt power cord, that could be run straight to the battery may be available.

You can leave the 1800w MSW inverter in place, and add a PSW inverter to the same battery bank.

You can also add another battery bank just to run the PSW as long as there is a way to recharge that bank.

You run 120v from the PSW to where the ASV plugs in -extension cord can run outside and back in if there is access. It is only for when you are parked.

You need to supply the sine wave inverter with 12v power and connect the device to the sine wave inverter.

Could replace the existing 1800 inverter with a sine wave model.

Or the separate sine wave inverter could be connected all neat and safe to the single branch circuit you need for the ASV and O2 machine.

tarnold wrote:
So could I just plug the pure into the modified?

No. That's not how it works. You also called it a converter. I think you need professional help.