So, I have been using my 12v(6.6 amps) C-Pap machine for a few years in my Creek Side. Now..........my wife is using a C-Pap. So far I have had my wife use my home unit(same exact one as in the trailer) on her side of the Queen size bed. The pressure on my unit is just a hair higher then hers is set for. With both units running all night without the humidifiers running has a very minimal affect on our 2-6v series 200a battery set up. Well, she wants her own, not mine. So hers is a 24v unit that uses 3.7 amps. Again, mine is a 12v @ 6.6 amps. Thinking when I get the converter to jump the 12v up to 24v it will double the amp draw? That would be something like 7.4 amp. Which in reality is not much more then what I have going on now. Is my thinking right?

With only a very slight increase for the conversion, yes.

yes 7.4 at 12v = 3.7 at 24v but there will also be a slight conversion factorso maybe 7.8 amps at 12v

I'm going to guess her's is a resmed. battery power solutions makes a great 12V to 24V DC to DC converter for these units.

I think a few added comments might be of help for anyone who is not familiar with RV CPAP issues. First, Res Med makes CPAPs designed to run on 110 volts and also other units designed for 12 volt use. The 110 units seem to use a lot of power and for battery use they would also require an inverter which loses additional power in the form of heat. The 12 volt units comes with a transformer and can be used with 110. I found many of the providers do not understand the difference. So you might actually need to research the Resmed offerings and give the provider the appropriate part number.CPAPs can chew through a lot of battery power. According to the OP, his 12 volt model uses 6.6 amps. For 8 hours of use, that would be 53 amp hours. Two units running for a night would deplete the 200 AH batteries to less than 50 percent. The 6.6 amp draw sounds high and is probably the maximum with the humidifier running. My wife's unit pulls about 3 amps without the humidifier. Anyway, CPAPs pull a lot of power and if you are going to run a CPAP solely on battery power, you will need a substantial battery bank and you will need to run a generator or have a suitable solar system and plenty of sunlight.There are some new travel units that require minimal power, but you would need to go back to your sleep doctor to discuss the suitability.

ktmrfs wrote:I'm going to guess her's is a resmed. battery power solutions makes a great 12V to 24V DC to DC converter for these units.Yes, I have ordered the Resmed 12v DC/DC to 24v converter. I am pretty sure the only thing I will need to do to get it fired up is fabricate a pretty stout 12 gauge, 12v extension cord to get from my side of the bed to hers.

C-Pap power usage | Good Sam Community

62 Replies

SidecarFlip
Explorer III
Jun 28, 2017
Vintage465 wrote:
ktmrfs wrote:
Vintage465 wrote:
SidecarFlip wrote:
Interesting reading. I use an S8 in my TC, running 2 Trojan 6 volt batteries and an AIMS power remote switching PSW 1500 watt and after 8 hours continuous use my SeeLevel battery monitor still shows 80 percent capacity in my batteries in the morning.

I use a passive (air over) humidifier, not as heated one.Hard to find but worth the trouble.

I also use the S8 on hunting trips running off a Lithium Ion battery pack and a MSW 500 watt inverter (passive again) and 2 Li packs run the machine for 3 8 hour nights and charging is a cigarette lighter plug away.

I have no issues in the TC or in a tent.

I am running two cpap machines. That is why I may be using more. But with two machines, if I only tug it down to 75-80% of capacity, my solar always packs me back up by noonish.

even with two machines, not using humidifier, it sound like a higher than expected draw. my one machine, the airsense 10 draws at most 8AH/night, actually closer to 5AH. so even at 10AH/night each, that's 20AH total, or not quite 10 percent on a pair of golf carts. you should be staying above 90 percent if that's all that is drawing current. I suspect things like your fridge, CO detector, propane detector, stereo even in off is really standby, are all drawing as much or more than a CPAP machine.

and trying to determine battery SOC by only looking at battery resting voltage is difficult.

Yes I was thinking all the little green and red lights all over the trailer would be adding to the drop

Because I have a TC and not a trailer, I can keep the parasitic losses to a minimum. The only green light I have is the CO detector and 3 amber led's on the fridge. No nightlights on either. Just pitch black and sleeping.

No TV and no stereo. I use a C Crane Solar Observer am/fm NOAA weather radio for entertainment and it's solar powered.

Every light bulb inside and outside are LED.
SidecarFlip
Explorer III
Jun 28, 2017
Why I use a passive hunidifier. Keeps the power consumption lower.
ktmrfs
Explorer II
Jun 27, 2017
MEXICOWANDERER wrote:
This morning:

Respironics BiPAP

14.0 inspiration

11.0 expiration

Duration: 7 hours 09 minutes

Without humidifier

6.62 ampere hours. 12.00 volts lab power supply input.

Allow me to demonstrate a sample :)

A 12 watt fan would stir papers at six feet. And with BiPAP fan disabled, the BiPAP unit electronics draws .09 ampere. LCD display lamp off.

your daily AH is consistent with my resmed air sense CPAP without the humidifier, and also consistent with a resperonics unit I had previously.
MEXICOWANDERER
Explorer
Jun 27, 2017
This morning:

Respironics BiPAP

14.0 inspiration

11.0 expiration

Duration: 7 hours 09 minutes

Without humidifier

6.62 ampere hours. 12.00 volts lab power supply input.

Allow me to demonstrate a sample :)

A 12 watt fan would stir papers at six feet. And with BiPAP fan disabled, the BiPAP unit electronics draws .09 ampere. LCD display lamp off.
Vintage465
Nomad
Jun 27, 2017
ktmrfs wrote:
Vintage465 wrote:
SidecarFlip wrote:
Interesting reading. I use an S8 in my TC, running 2 Trojan 6 volt batteries and an AIMS power remote switching PSW 1500 watt and after 8 hours continuous use my SeeLevel battery monitor still shows 80 percent capacity in my batteries in the morning.

I use a passive (air over) humidifier, not as heated one.Hard to find but worth the trouble.

I also use the S8 on hunting trips running off a Lithium Ion battery pack and a MSW 500 watt inverter (passive again) and 2 Li packs run the machine for 3 8 hour nights and charging is a cigarette lighter plug away.

I have no issues in the TC or in a tent.

I am running two cpap machines. That is why I may be using more. But with two machines, if I only tug it down to 75-80% of capacity, my solar always packs me back up by noonish.

even with two machines, not using humidifier, it sound like a higher than expected draw. my one machine, the airsense 10 draws at most 8AH/night, actually closer to 5AH. so even at 10AH/night each, that's 20AH total, or not quite 10 percent on a pair of golf carts. you should be staying above 90 percent if that's all that is drawing current. I suspect things like your fridge, CO detector, propane detector, stereo even in off is really standby, are all drawing as much or more than a CPAP machine.

and trying to determine battery SOC by only looking at battery resting voltage is difficult.

Yes I was thinking all the little green and red lights all over the trailer would be adding to the drop
ktmrfs
Explorer II
Jun 27, 2017
Vintage465 wrote:
SidecarFlip wrote:
Interesting reading. I use an S8 in my TC, running 2 Trojan 6 volt batteries and an AIMS power remote switching PSW 1500 watt and after 8 hours continuous use my SeeLevel battery monitor still shows 80 percent capacity in my batteries in the morning.

I use a passive (air over) humidifier, not as heated one.Hard to find but worth the trouble.

I also use the S8 on hunting trips running off a Lithium Ion battery pack and a MSW 500 watt inverter (passive again) and 2 Li packs run the machine for 3 8 hour nights and charging is a cigarette lighter plug away.

I have no issues in the TC or in a tent.

I am running two cpap machines. That is why I may be using more. But with two machines, if I only tug it down to 75-80% of capacity, my solar always packs me back up by noonish.

even with two machines, not using humidifier, it sound like a higher than expected draw. my one machine, the airsense 10 draws at most 8AH/night, actually closer to 5AH. so even at 10AH/night each, that's 20AH total, or not quite 10 percent on a pair of golf carts. you should be staying above 90 percent if that's all that is drawing current. I suspect things like your fridge, CO detector, propane detector, stereo even in off is really standby, are all drawing as much or more than a CPAP machine.

and trying to determine battery SOC by only looking at battery resting voltage is difficult.
Vintage465
Nomad
Jun 27, 2017
beemerphile1 wrote:
Vintage465 wrote:
...I may have to look into one of the little "Mr. Heater" Free Standing Catalytic heaters for real cold nights.....

FWIW, I don't believe Mr. Heater produces any portable catalytic heaters, only blue flame heaters. The Buddy line of heaters are all blue flame heaters.

Gonna say I need some schooling on this then! I will look further into these. I was thinking by the looks, they were catalytic heaters.
Vintage465
Nomad
Jun 27, 2017
SidecarFlip wrote:
Interesting reading. I use an S8 in my TC, running 2 Trojan 6 volt batteries and an AIMS power remote switching PSW 1500 watt and after 8 hours continuous use my SeeLevel battery monitor still shows 80 percent capacity in my batteries in the morning.

I use a passive (air over) humidifier, not as heated one.Hard to find but worth the trouble.

I also use the S8 on hunting trips running off a Lithium Ion battery pack and a MSW 500 watt inverter (passive again) and 2 Li packs run the machine for 3 8 hour nights and charging is a cigarette lighter plug away.

I have no issues in the TC or in a tent.

I am running two cpap machines. That is why I may be using more. But with two machines, if I only tug it down to 75-80% of capacity, my solar always packs me back up by noonish.
ktmrfs
Explorer II
Jun 27, 2017
SidecarFlip wrote:
That is a good presentation for sure. Now I know why my +90 condensing furnace (in out house running on propane) makes so much water and why the exhaust develops a lot of ice around it in the winter time...all water. I was considering a Wave heater for my next unit. Reading that, I think I'll stick to a forced air unit and deal with the amp draw.

and these furnaces get quite a bit of extra efficiency and heat out of condensing water from vapor to liquid. water releases a great deal of heat when it goes from a vapor state to a liquid. Conversly it takes a great deal of energy to get water from a liquid to vapor, notice how water will sit near boiling for quite a while before coming to a full boil.
SidecarFlip
Explorer III
Jun 27, 2017
Only thing I know about 'Buddy' heaters is that I use one in my hunting blind in the winter to take the chill off.

I also have a Coleman catalytic heater that uses Coleman fuel. Both work well in the winter.

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C-Pap power usage

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