System One REMstar Auto CPAP - direct connect to 12V batt?

I received a PR System One REMstar Auto CPAP Machine with A-Flex machine from my DME, and saw that I can buy a 12 Volt DC Power Cord for it.

My question - is this just a direct connection to the battery, or does it have some kind of voltage regulation built in? Looking at the (small) picture, I didn't see any obvious electronics.

Does the CPAP unit handle the voltage from a direct 12V battery (like 13.5V for a fully charged battery)?

I can wire up a direct connection and save the $$ if this is the case.

Thanks,

Steven

Yep! I think I remember that the center is "hot"...but double-check that before you plug it in. Or your "flow generator" becomes a "smoke generator"!

The manufacturer warns not to use the 12V adapter while the engine is running.

I warn you especially not to crank the engine while the machine is hooked up to the battery.

There's no voltage regulation in the cord. Hook it up to any car battery or other "normal" 12V battery. When the battery voltage drops too far, the machine will quit working at some point. Other than that, it should work just fine.

If you hook the battery up to a battery charger while using the machine, there's a theoretical possibility of the charger doing something bad. The charger is designed to charge a "dumb" battery, not run an electronic device. If you try it, it will probably work just fine, but don't come yelling at me if it eats your CPAP machine.

The PRS1 machines will run the humidifier off the 12V supply. If you use the humidifier, you will run the battery down a lot quicker.

Warning: Some ResMed machines use the same plug, but opposite polarity. Switch them and the CPAP machine goes BOOM!

I bought the cable and it does have two really heavy pieces on it. I did ask here what they were and someone replied, but I don't recall what they do. The consensus was you could make the cable from parts at Radio Shack and be just fine.

davelikesbeer wrote:I bought the cable and it does have two really heavy pieces on it. I did ask here what they were and someone replied, but I don't recall what they do. The consensus was you could make the cable from parts at Radio Shack and be just fine.

The two heavy pieces are "toroids." They block radio frequency noise. i.e. They keep radio interference from coming out of the machine and making the wire act like an antenna and interfere with cell phones, etc. They also prevent the wire from acting like an antenna and picking up cell phone and other radio signals and getting into the machine and interfering with the CPAP machine.

They will do very little in terms of protecting from spikes, voltage variations, etc.

At least that's what they look like. I would have to cut them open to be sure, but they look like the usual RFI toroids I've seen on dozens of other electronic cables.

Things will probably work just fine without the toroids, but maybe not. Manufacturers have a certain responsibility to make sure their devices don't interfere with radio and other devices. Medical manufacturers need to worry about devices interfering with their therapy devices.