Cpap Machine

[Chiefdeck]

Is it possible to run Cpap machine just using trailer batteries or do I need to also use generator and or shore power?

[theSane]

How much power does it draw?
What capacity are your batteries?
Are you running anything else overnight (residential fridge)?


Edit:
Found this site which should help with the calculations and has some safety information.

[al1florida]

Originally Posted by Chiefdeck

Is it possible to run Cpap machine just using trailer batteries or do I need to also use generator and or shore power?

If you will leave the CPAP humidifier heater off, it will probably work just fine.

My wife's CPAP pulls about 1 amp of DC power (8-9 amp hours a night) as long as the heater is off. If we turn on the humidifier heater it pulls about 4-7 amps or more, depending on how high you turn up the heater. We have been dry camping or boondocking using her CPAP for over 7 years.

If you use CPAP humidifier heater and it pulls 5 amps, that uses about 40AH of battery power. If you have a single group 24 or 27 battery, that uses almost 50% of the battery overnight. It is best not to discharge more than 50% of the battery capacity if you want decent battery life.

Her CPAP uses 12V DC and the MFG sold us a 12V cord we plug directly into a 12V outlet. If we were to us the 120V AC power cord that came with the CPAP I would buy a small 100 watt inverter and plug it into a 12V outlet in the RV.

Some or most of the newer CPAP's use 24V DC. If so you will need to use the inverter option. If you look at your CPAP you will find a label somewhere (usually on the bottom) showing the operating voltage.

What are your plans to recharge the battery each day? If you do use 50% of your battery capacity it takes probably about 4-8 hours of generator time to get the battery full again. A lot of the charging time depends on your charger.

How many batteries do you have and what size batteries?

[pmglidden]

This site has options for running your CPAP off 12v

https://www.cpap.com/cpap-battery-power/cpap-dc-cables

You’ll need to plug it into a cigarette lighter for this to work. We don’t have one of those near the bed on our 2306BHS, so I’m trying to come up with some options. Maybe run a new wire over to the bed.

Another option would be to run your cpap off a separate battery. That same site has some good options that’ll last a couple days without a charge. Another good reason to use a separate battery is that you can use it at home in case of a power outage .

[al1florida]

Originally Posted by pmglidden

This site has options for running your CPAP off 12v

https://www.cpap.com/cpap-battery-power/cpap-dc-cables

You’ll need to plug it into a cigarette lighter for this to work. We don’t have one of those near the bed on our 2306BHS, so I’m trying to come up with some options. Maybe run a new wire over to the bed.

Another option would be to run your cpap off a separate battery. That same site has some good options that’ll last a couple days without a charge. Another good reason to use a separate battery is that you can use it at home in case of a power outage .

Many times there is a wall lamp at the head of the bed with an on/off switch on the lamp fixture. If there is an on/off switch you can wire in a 12V outlet to the wires on the back of the lamp for your CPAP.

[Chiefdeck]

Thanks everybody, looks like the seperate battery is the way to go

[Fasttimes]

If you have 12v power to an outlet in your bedroom your set. In my case, I didn't. I'm now using one of these power banks. They are great, so good I bought two of them. I also use a 12v adapter with my cpap as it's more efficient than plugging straight in with your regular 120v power cord.



There is a $50 off coupon right now.


https://www.amazon.com/dp/B07WQN41V9/ref=cm_sw_em_r_mt_dp_U_0cyVEb6WCS7ZG





https://www.thecpapshop.com/dc-power...ense-10-series

[Chiefdeck]

I do not really understand all the terms and what they mean, i have these 2 power supply units for my telescope would either of these power the cpap
https://www.bhphotovideo.com/c/produ...gaAiooEALw_wcB
https://www.bhphotovideo.com/c/produ...saAnKaEALw_wcB

[Fasttimes]

Originally Posted by Chiefdeck

I do not really understand all the terms and what they mean, i have these 2 power supply units for my telescope would either of these power the cpap
https://www.bhphotovideo.com/c/produ...gaAiooEALw_wcB
https://www.bhphotovideo.com/c/produ...saAnKaEALw_wcB

What model/brand of CPAP do you have?



The only output I see on those two devices seems to be USB connections. So in order to use something like that you would need to see if it's possible to get a connector that goes USB to your CPAP power connector. Not saying it's not possible, but not common for sure.

[BobC]

Originally Posted by Chiefdeck

I do not really understand all the terms and what they mean, i have these 2 power supply units for my telescope would either of these power the cpap
https://www.bhphotovideo.com/c/produ...gaAiooEALw_wcB
https://www.bhphotovideo.com/c/produ...saAnKaEALw_wcB

The first unit has the largest capacity at 159Wh (watt hours) capacity, which is 159Wh/12v = 13.5 Ah (amp hours). The second is rated at 7 Ah (amp hours). If your CPAP draws about the same 8 - 9 Ah/night as al1Florida's, you should be OK using the first unit, the second being too small for the night. Note that both units do list 12v car outputs that you can plug in to with an appropriate 12v cord. Note that the capacity specifications are "under ideal conditions" when new so you may not get the full 13.5 amp hours out of the unit.

The only way to be sure is to try it. You won't be risking damage to either the CPAP or your Celestron power supply.

Good luck.

[al1florida]

As BobC posted the batteries have a 12V port so you could plug your CPAP directly into the 12V port IF your CPAP operates off of 12V and you can buy or make a 12V power cord.

If your CPAP is 24V then you need a 12V to 24V adapter or an inverter to supply 120V AC. Both those have power losses involved in operating the electronics to change the electricity. Those losses may make your power usage to great for the batteries to make it though the night.

Your two batteries would most likely get you through one nights use of the CPAP. However what components are you going to use to supply the 6 hours of charging time to get the batteries recharged so you can use them the second night?

[Chiefdeck]

I think we are going to go with a dedicated battery for the cpap, seems like the easiest way to go

[golden13]

Contact the manufacturer of the cpap, or the company that provides your supplies. Ask them if they have a 12v adapter for use in a car. Most cpap machines run on low voltage DC power, so it probably exists. It would be FAR more economical than inverting your 12v supply to 110v ac and plugging your wall wart adapter into that.

[Dstrand100]

My machine would not work running off 12 DC. It has to be plugged into 110 VAC which is then transformed and reduced to 12DC.

[al1florida]

Originally Posted by Dstrand100

My machine would not work running off 12 DC. It has to be plugged into 110 VAC which is then transformed and reduced to 12DC.

Almost 100% that the power cord that came with your CPAP has a transformer and some other circuitry to change the 120V AC to 12V DC.
The MFG of your CPAP most likely has a 12V cord so you can plug the CPAP directly into auto/RV 12V power.

[tinglett]

I have an ResMed Airsense 10 cpap machine with a power brick that says it produces 24V at 3.75A. Shortly after getting the machine last year I asked about 12v converters and the store only pointed me to 125v inverters. I was just thinking about this again and found this thread. With a quick search I found there is indeed a 12v to 24v converter which I ordered and will receive next week. When I get it, I'll try to determine how efficient it is compared to using a 125v inverter setup.

As a start, last night I ran the cpap with a kil-o-watt meter in our house. It used 110 watt hours (0.110 kwh). I keep the temp way down low so I don't believe it tried to do any heating. I'll measure for a few days and make sure the heating is completely off (and experiment with it on as well).

By the way, I noticed it uses a variable amount of power based on your breathing. It was rapidly varying between about 8 watts and 12 watts. I didn't test it long this way, but it seemed rather bounded in this range, and it aligns with my overnight measurement which had a duration of around 7.5 hours. I did notice that it blasted up to 42 watts when I pulled the mask from my face. Mine shuts down automatically and very quickly when that happens (i.e, the lazy way to turn it off) so little energy is lost, but it is a factor for sizing the supply. Still, a 100w inverter would have plenty of headroom for my unit.

Todd

[DavidM]

I suspect you will find that running your CPAP from 12V and converting it to the 24V that it requires, is about as efficient as running it from a 12V to 120V AC inverter and power it through the brick.

Your wattage measurements were obviously made while powered with the 120V AC brick as the Kill-o-Watt is only AC. 8-12 watts is rather low from what I read, so you shouldn't have any problem power it either way- inverter and brick or 12-24V converter.

If you go with an inverter then a 100 watt unit sounds fine. Many Winnies have inverters built in but I bet that the efficiency of a 100 watt inverter supplying 8-12 watts would be better than a 1,000 watt or greater built in inverter.

David

[tinglett]

Originally Posted by DavidM

I suspect you will find that running your CPAP from 12V and converting it to the 24V that it requires, is about as efficient as running it from a 12V to 120V AC inverter and power it through the brick.

Yeah, I suspect the 12V to 24V brick is really a switching power supply like most bricks (i.e., an inverter internally) so it'll probably have similar efficiency as the 125V ac to 24V dc brick. I won't have the additional overhead of an AC inverter, but at these rates I'm guessing that additional inefficiency will be lost in the noise. So I'm probably wasting the $85 on this new 12V brick. We'll see, and I'll post here so nobody else wastes their money .

I haven't been using the cpap on battery so far, and I doubt I can even get 50AH from my bog standard deep cycle battery, so I think I'm looking at a pretty big hit to the battery each night. I might be ok for a weekend, but I'll either need a battery upgrade or an external battery pack. I haven't owned this trailer long so I don't really want to dive into big upgrades, so I'll probably get the external battery for the short run. Besides, I can take it to a shelter or bath and (hopefully) charge it up again pretty fast if necessary.

Todd

[Marine359]

Originally Posted by tinglett

Yeah, I suspect the 12V to 24V brick is really a switching power supply like most bricks (i.e., an inverter internally) so it'll probably have similar efficiency as the 125V ac to 24V dc brick. I won't have the additional overhead of an AC inverter, but at these rates I'm guessing that additional inefficiency will be lost in the noise. So I'm probably wasting the $85 on this new 12V brick. We'll see, and I'll post here so nobody else wastes their money .

I haven't been using the cpap on battery so far, and I doubt I can even get 50AH from my bog standard deep cycle battery, so I think I'm looking at a pretty big hit to the battery each night. I might be ok for a weekend, but I'll either need a battery upgrade or an external battery pack. I haven't owned this trailer long so I don't really want to dive into big upgrades, so I'll probably get the external battery for the short run. Besides, I can take it to a shelter or bath and (hopefully) charge it up again pretty fast if necessary.

Todd

I have a Phillips system one cpap which draws about 5 amp when using the humidifier. I can’t really do well without the humidifier. There’s a cigarette lighter 12v power supply available on Amazon which should reduce watt hour consumption, but I can’t find any info on how much. Right now installing 170ah lithium, so I’ll have plenty of power. Wondering if the 12v power supply will reduce load enough to justify its purchase price.

[tinglett]

Originally Posted by Marine359

I have a Phillips system one cpap which draws about 5 amp when using the humidifier. I can’t really do well without the humidifier.

Do you mean the power brick is rated 5A @ 12v? Or maybe you measured between the power brick and the cpap? I assume you don't mean 5A @ 120v (600w)!

I did eventually take more measurements of my cpap, but I didn't have the humidifier running. Also, of course my cpap is a very different model. So maybe think of these as relative measurements to each other.

I did measurements with a cheapo Bayite shunt meter. This measured 12v power usage in watt-hours over time via a shunt. I had this setup specifically for the cpap, so no other power was going through it. My lithium setup is generally running at around 13.3v if you want to divide watt-hours to estimate get amp-hours. I'd run this setup overnight, but of course I'd sleep different lengths of time so I divided by number of hours to get a baseline.

With the $85 12v DC-DC brick I was measuring about 7.5 - 8.0 watt-hours per hour of using the cpap. That is, if it ran for 8 hours I would use 60 to 64 watt-hours overnight, which would translate to about 4.5 to 4.8 Ah. That aligns with your measurement, and you have the humidifier going which is very impressive!

With a cheap Stanley 100w inverter along with my cpap's AC brick I was measuring about 18.5 watt-hours (total) per hour of using the cpap. So think approx 2x the power usage! Now keep in mind that my inverter really is junk (I think) so perhaps that aspect could be greatly improved with a better inverter. But in the end it was clear to me with this setup that inefficiencies in the power brick and inverter really do add up to something significant.