12 v operation with Respironics M series Auto with C-flex

I am running a Respironics M seris Auto with C-flex. I have a 12 volt adapter for use with a 12 volt automotive battery that is on a maintainence charger when not used. I am not able to run my machine with it connected directly to a battery. The machine powers up and the lights illuminate, however, when I press the start button, the fan runs for a second and then it shuts down.

I cannot understand why this is happening. Has anyone had the same issue? I when camping this weekend without my CPAP and I did not sleep well.

A few points for those who might ask:

• I have the correct polarity.
  I have the correct sized plug.
  I am not using the humidier.
  I have tried the plug directly on the back of the machine (not the humidifier) with the humidifer detached.
  I measured the voltage of the battery (13.8 v)
  I have tried this on one of my cars with a live cigarrette plug (engine off).
  I have measured amperage at the terminal in series with the battery clip and see no massive spikes in current. Just a minor amount of power.

Linus wrote:I am running a Respironics M seris Auto with C-flex. I have a 12 volt adapter for use with a 12 volt automotive battery that is on a maintainence charger when not used. I am not able to run my machine with it connected directly to a battery. The machine powers up and the lights illuminate, however, when I press the start button, the fan runs for a second and then it shuts down.

I cannot understand why this is happening. Has anyone had the same issue? I when camping this weekend without my CPAP and I did not sleep well.

A few points for those who might ask:

• I have the correct polarity.
  I have the correct sized plug.
  I am not using the humidier.
  I have tried the plug directly on the back of the machine (not the humidifier) with the humidifer detached.
  I measured the voltage of the battery (13.8 v)
  I have tried this on one of my cars with a live cigarrette plug (engine off).
  I have measured amperage at the terminal in series with the battery clip and see no massive spikes in current. Just a minor amount of power.

Did you measure the battery voltage when the machine powered on? If the battery can't maintain the current draw the machine will shut off.

You didn't say where you got the wire & plug for this. IF the wire is not large enuff to carry the current draw it likely will NOT power up. So tell us about this wire?

The failure condition you describe sounds to me like a battery with high internal impedance. This is a very common failure mode for lead-acid batteries, especially gel cells. As Gumby CT said, the test is simple. measure the battery terminal voltage with the machine off, then turn it on. If the voltage drops more than a few tenths of a volt, its a high impedance battery. Too low a wire gauge is not likely a problem here unless the gauge size is very small (24 or smaller; that said, I wouldn't use anything smaller than 20 gauge, and 18 gauge would be even better) and/or the wire run is long. What you ultimately use depends on how hard it is to terminate the various plugs used.

The battery is a Mercedes Benz Battery. The wire itself is thin. I am thinking that the wire is the cause. I am not sure what to do about a lead acid battery other than going with Lithium Iron Phonsphate or Lithium Cobalt Exide. Both are very expensive. Ther Lead acid battery is free.

I can say that I have had the plug for a long time (baybe 20 years). I will check the operating voltage too. I had the same issue with a 12 v power supply (high amperage).

Thanks for the suggestions.

Linus wrote:The battery is a Mercedes Benz Battery. The wire itself is thin. I am thinking that the wire is the cause. I am not sure what to do about a lead acid battery other than going with Lithium Iron Phonsphate or Lithium Cobalt Exide. Both are very expensive. Ther Lead acid battery is free.

I can say that I have had the plug for a long time (baybe 20 years). I will check the operating voltage too. I had the same issue with a 12 v power supply (high amperage).

Thanks for the suggestions.

I'll bet a dollar the thin wire is the problem.

I bought mine from Radio Shack. The requirements I had were -
1. a fuse - I wanted it to have a fuse which would be easily available.
2. LED - I want an indication that the power is available
3. It had to carry at least 3A - I think the one I bought was capable of 5A

I thought about a switch - but that is just another point of potential failure and confusion. If it needs to be switched off, I just unplug it.

The one I bought was pre-made but you had to buy a connector separate. I think they called it Adapta Plug cuz you can buy whatever size you need. I think for my M Series it uses and N connector. Bring your machine in to have them check it if in doubt.

Then the key is to get the polarity right - for my M it needs a Positive tip.

Next of course you want to try it out BEFORE you need it - like when the power goes out or you're going camping. You also want to know how long your battery will last at your pressure.

Check out this link to see if this will help you. I don't know if this has the LED but should be adequate as long as you aren't using a DC Humidifier too. If you are - Me thinks you will need to work out something else.

http://www.radioshack.com/product/index ... Id=3802147
Enercell™ Heavy-Duty 12V/5A Power Cord (8-Ft.)
Model: 270-048 | Catalog #: 270-048 $10.99

PS. You could always buy the Respironics spec'd cable from cpap.com

Good Luck

If you are having problems with both your battery and with a suitable power supply, this suggests a different problem.

Based on the experience I have had with cigarette lighter plugs over the years (notoriously unreliable!!), it would be unusual if one of these was wired with wire so thin that it would cause your machine to shut down at motor start.

Does the machine give any kind of error code when it shuts down? Do the lights dim upon startup? What else does the machine do/not do? Any unusual noises? Does the display, etc. stay on after the motor stops? Ever blow a fuse in the cigarette lighter adapter?

I am concerned you might have a problem with the DC power supply inside the machine.

i would definitely try a different cable. I have been using the one from Respironics, it is very well built, it is fused with heavy wire and has two inline filters. I tried a "cheaper" cable made for a radar detector and it behaved as you described, the lights would light up until you pushed the button then they would go out it they would reset. While the cable looked heavy duty when I cut it open it was only a very thin wire 36 gage. My current system I have been using is a 1-1/2 amp float charger continuously hooked up to a 75 Amp hour deep cycle battery. then through the Respironics cable into the humidifier. While camping I have gone three, eight hour sleep nights with humidifier on without charging. At home I just leave the charger plugged in and it works like a UPS and I don't worry about power outages, we have had three since the start of the year.

GumbyCT wrote:

Linus wrote: The wire itself is thin. I am thinking that the wire is the cause.

I'll bet a dollar the thin wire is the problem.


http://www.radioshack.com/product/index ... Id=3802147
Enercell™ Heavy-Duty 12V/5A Power Cord (8-Ft.)
Model: 270-048 | Catalog #: 270-048 $10.99

PS. You could always buy the Respironics spec'd cable from cpap.com

Good Luck

Since there are no takers - I will withdraw my offer. I would still like to hear the outcome from Linus.
But I remain resolutely certain a larger gauge wire (to handle 3A) will resolve this problem.

A battery may show 13.8v but be dead. You need to measure the voltage when you turn the cpap on.
If it's shot the voltage under load will go low right after you power the cpap up. I seriously doubt
that that thin wire would be your problem.

Okay folks. First of all I want to thank you. You are awsome! It was the wire. It was too thin. Gumby, you were right. Where do I send the dollar?

I went to radio shack and bought the heavy duty 5 amp cable. It would not work on their power supply there because it is only able to provide 3 amps. I am sure that my CPAP probably has a start up surge... I digress...

Anyways I gave it a try in my car. It works. When I got home, I tried my battery that sits in my garage. It too works. I pulled this battery out of my car a few months ago a preventative maintenance. I replaced it early. So I have an extra bettery. Right now it is in a battery box and I have a battery maintenance charger hooked up to it. I am going to run my CPAP tognight with the humidifier in pass over mode to see how well it works.

No more camping without breathing. Since I started CPAP (about 1.5 years ago) I have only gone four nights without. Two of these nights were because I forgot a part when I traveled, and other two last weekend when I camped without my CPAP.

It works after a night on the battery. Voltage after a night was 12.6. This is pretty much around the level last night after pulling it off of the charger. I am spending the moring putting a charge back into it so that it will be ready for the next camping trip. Also I am searching for some solar panels and a battery regulator.

I ran without the humidifer running and left my heated hose unplugged. It was cold last night so I a left my windows open to simulate a night up in the mountains. It felt slightly dry having just the pass over setting for the humidifer and the air felt much colder than I am used to having. I have been using a heated hose close to my starting point for CPAP. Other than the cold, I am good to go.

Again. Thanks for all the help.

Linus wrote:Okay folks. First of all I want to thank you. You are awsome! It was the wire. It was too thin. Gumby, you were right. Where do I send the dollar?

I went to radio shack and bought the heavy duty 5 amp cable. It would not work on their power supply there because it is only able to provide 3 amps. I am sure that my CPAP probably has a start up surge... I digress...

Anyways I gave it a try in my car. It works. When I got home, I tried my battery that sits in my garage. It too works. I pulled this battery out of my car a few months ago a preventative maintenance. I replaced it early. So I have an extra bettery. Right now it is in a battery box and I have a battery maintenance charger hooked up to it. I am going to run my CPAP tognight with the humidifier in pass over mode to see how well it works.

No more camping without breathing. Since I started CPAP (about 1.5 years ago) I have only gone four nights without. Two of these nights were because I forgot a part when I traveled, and other two last weekend when I camped without my CPAP.

I am glad it helped. Hopefully others will also get something from it.

Write on the dollar "Gumby was write" - put it in the nearest US mail box, we'll see where it ends up. You know kinda like Where in the World is George.

I agree gumby is right on the money.I bought the same Radio Shack setup a few years ago before a trip to wva from florida,both wife and i use the machines when traveling we have the same respironics machines and also i might mention i bought a cigarette lighter plug adapter to alligator clips and packed my trolling motor battery in the car in case i needed a power backup should i stop off in rest area and not drain the car power when shut down. I use the resmed machines at home that insurance supplied but love to take the respironics i bought as backup on the road.I leave them packed in their case and if i have to go at a moments notice they are ready to roll without bothering my home machine next to the bed.

Blown Fuse UPDATE
Since I had a fuse blow in my Respironics special DC cable (has a 3A 250V slo blo fuse in it) I wanted to keep some of this info together. I bought replacement 5A fuses at the local auto parts store to have spares for camping, travel, storms, etc.

GumbyCT wrote:I bought mine from Radio Shack. The requirements I had were -
1. a fuse - I wanted it to have a fuse which would be easily available.
2. LED - I want an indication that the power is available
3. It had to carry at least 3A - I think the one I bought was capable of 5A

I thought about a switch - but that is just another point of potential failure and confusion. If it needs to be switched off, I just unplug it.

The one I bought was pre-made but you had to buy a connector separate. I think they called it Adapta Plug cuz you can buy whatever size you need. I think for my M Series it uses and N connector. Bring your machine in to have them check it if in doubt.

Then the key is to get the polarity right - for my M it needs a Positive tip.

Next of course you want to try it out BEFORE you need it - like when the power goes out or you're going camping. You also want to know how long your battery will last at your pressure.

Check out this link to see if this will help you. I don't know if this has the LED but should be adequate as long as you aren't using a DC Humidifier too. If you are - Me thinks you will need to work out something else.

http://www.radioshack.com/product/index ... Id=3802147
Enercell™ Heavy-Duty 12V/5A Power Cord (8-Ft.)
Model: 270-048 | Catalog #: 270-048 $10.99

PS. You could always buy the Respironics spec'd cable from cpap.com

Good Luck