Confused about run times for CPAP battery banks

I have a Dreamstation 1 CPAP that says it uses 6.67 amps at 12 volts, or about about 80 watts of power. It appears this must include the humidifier.

How does a CPAP battery with 160 watt hours of power manage to power a Dreamstation 1 for 8 hours? Does the CPAP really not take 80 watts? My minimum pressure is 15 so my power usage would be on the higher end. At 80 watts I would need 640 watt hours minimum to power my CPAP for 8 hours. I am thinking about getting a Kill-A-Watt meter to see what it really uses.

reader2580 wrote: ↑

Wed May 03, 2023 10:57 am

I have a Dreamstation 1 CPAP that says it uses 6.67 amps at 12 volts, or about about 80 watts of power. It appears this must include the humidifier.

The blower alone draws less than 5 watts at 15 cmH2O.

reader2580 wrote: ↑

Wed May 03, 2023 10:57 am

I have a Dreamstation 1 CPAP

Are you using a machine that was replaced under the DreamStation One recall?

reader2580 wrote: ↑

Wed May 03, 2023 10:57 am

I have a Dreamstation 1 CPAP that says it uses 6.67 amps at 12 volts, or about about 80 watts of power. It appears this must include the humidifier.

How does a CPAP battery with 160 watt hours of power manage to power a Dreamstation 1 for 8 hours? Does the CPAP really not take 80 watts? My minimum pressure is 15 so my power usage would be on the higher end. At 80 watts I would need 640 watt hours minimum to power my CPAP for 8 hours. I am thinking about getting a Kill-A-Watt meter to see what it really uses.

You turn off the humidifier when you're on battery.

reader2580 wrote: ↑

Wed May 03, 2023 10:57 am

I have a Dreamstation 1 CPAP that says it uses 6.67 amps at 12 volts, or about about 80 watts of power. It appears this must include the humidifier.

Get the kill-a-watt. It's not using 6.67 amps.

ChicagoGranny wrote: ↑

Wed May 03, 2023 11:50 am

Are you using a machine that was replaced under the DreamStation One recall?

My regular machine is a Resmed. Yes, this Dreamstation 1 was replaced under recall. I want to use the Dreamstation 1 for away from home and keep the Resmed for home use.

palerider wrote: ↑

Wed May 03, 2023 12:52 pm

You turn off the humidifier when you're on battery.

I am definitely planning to turn off the humidifier. I think I need to get the Kill-A-Watt to see what it really uses. I don't want to have to spend more than necessary on a battery. I can charge up every day.

reader2580 wrote: ↑

Wed May 03, 2023 1:48 pm

palerider wrote: ↑

Wed May 03, 2023 12:52 pm

You turn off the humidifier when you're on battery.

I am definitely planning to turn off the humidifier. I think I need to get the Kill-A-Watt to see what it really uses. I don't want to have to spend more than necessary on a battery. I can charge up every day.

Generally machines use less than 100wh a night, depending on pressure.

reader2580 wrote: ↑

Wed May 03, 2023 1:48 pm

palerider wrote: ↑

Wed May 03, 2023 12:52 pm

You turn off the humidifier when you're on battery.

I am definitely planning to turn off the humidifier. I think I need to get the Kill-A-Watt to see what it really uses. I don't want to have to spend more than necessary on a battery. I can charge up every day.

If you're talking about a lead acid chemistry battery, you want to avoid discharging it too deeply, like 50% at most. You'll shorten its useful life span significantly if you deep cycle it. Lithium ion, probably not so much of an issue. I would still opt for some extra capacity regardless of the type of battery.

I don't know by the numbers, but I have a 200W portable "power station" (FlashFish Brand). I don't use a humidifier and I use about 2/3 of the power in 8 hours with my CPAP. This is a nice size (about the size of a shoebox), fairly lightweight, and it can be recharged with AC, the car battery, or solar (if you have a solar panel--they bundle a 50W portable panel for about $75 more). It would be OK for 1 night of camping, but not two. They have larger ones, too.

reader2580 wrote: ↑

Wed May 03, 2023 1:48 pm

I think I need to get the Kill-A-Watt to see what it really uses.

afaik the Kill-A-Watt only measures AC - you really want to know what the DC power draw is.

Plug the Kill-a-Watt between the main power cord and the wall outlet.
Once you know the AC wattage, then DC is also measured in watts.
It will at least give you a rough idea.

SleepGeek wrote: ↑

Thu May 04, 2023 7:09 pm

reader2580 wrote: ↑

Wed May 03, 2023 1:48 pm

I think I need to get the Kill-A-Watt to see what it really uses.

afaik the Kill-A-Watt only measures AC - you really want to know what the DC power draw is.

Seems like you'll get pretty close with a kill-a-watt, in the ballpark anyhow. This battery camping business is a little tricky with the power usage. You'll use more watt hours if you're doing an inverter vs direct DC, worse than a direct with 12V DC to 24V DC converter. The inverter IDK how much extra you would need but you definitely lose power in the conversion. Steer clear of that option if you can. That was one nice feature of the PRS1 series, the 12V direct connection with no conversion. Don't forget to turn off the heated humidifier and hose; you'll blow thru 100% of a modest battery in a few hours and regret it.

I will be using Lifepo4, not lead acid. The AC adapter uses some power, but measuring AC usage would get pretty close. I am planning on a direct DC connection to the Dreamstation.

reader2580 wrote: ↑

Fri May 05, 2023 7:21 pm

I will be using Lifepo4, not lead acid. The AC adapter uses some power, but measuring AC usage would get pretty close. I am planning on a direct DC connection to the Dreamstation.

If you want to get real precise, this is what I use to monitor my battery setup.

https://www.amazon.com/dp/B079JVGRSL/re ... RhaWw&th=1