Vehicle car battery as a CPAP power source?

There's a planned power outage in my apartment in the near future. I was wondering if using a regular vehicle battery like you buy at Costco and attaching a DC adapter for several hours of use would work or would the power requirements of the CPAP be too much and drain the battery?

Justin Case wrote: ↑

Sat Aug 21, 2021 12:02 am

There's a planned power outage in my apartment in the near future. I was wondering if using a regular vehicle battery like you buy at Costco and attaching a DC adapter for several hours of use would work or would the power requirements of the CPAP be too much and drain the battery?

Which model CPAP are you using and what are your pressure settings?

Different brands of CPAP use different voltages. We need to know the model and brand of CPAP you are using.

Justin Case wrote: ↑

Sat Aug 21, 2021 12:02 am

There's a planned power outage in my apartment in the near future. I was wondering if using a regular vehicle battery like you buy at Costco and attaching a DC adapter for several hours of use would work or would the power requirements of the CPAP be too much and drain the battery?

We do need to know what machine you are using and how you are planning to hook it up. Some machines are 12V, but some are 24V. Are you planning to use a DC to AC converter?

For a few hours it would most likely work, especially if you turn off the humidifier and heated hose if you use either of those.

It might not be to good for the battery, regular car batteries are good at providing lots of current for a few seconds to start a car, but not so good if you discharge them significantly.

We are currently expecting a hurricane to hit tomorrow here in CT, and I just brought home a Marine/RV deep cycle battery that I'm hoping to use nightly if we have an extended power outage. This may not be the best type of battery either, but I am hoping it will tolerate the discharge/recharge cycles the CPAP will put on it. My device uses 24V, so I have also purchased a 12V DC to 24V DC converter to run it off a single battery. I will turn off the humidifier and I don't use a heated hose. I need to look up the specs to try to figure out what the capacity of the battery will be, it lists "Cold Cranking Amps (CCA)" and "minutes of reserve". I think it should work for me, but I will recharge it during the day when I run a generator.

We definitely have experts here who can answer more. Good luck!

Jim

I’ve used a jump-starter unit (glass mat battery inside, runs 12v output, air pump, etc.). That was a 22 amp hour battery, which could run my PRS1 CPAP all night, but then needed full recharge all day (I brought it to work, which had power). It has a carry handle (a car battery doesn’t). Supposedly it can be recharged plugged into the car’s 12v socket too, but I don’t have that cord (car charging is supposed to be faster too).

I now have a 20 amp hour glass mat battery and 12v power adaptor set aside (I top it off each month). Also easy to carry, and this particular glass mat battery has a built in handle. I think it is used in wheel chairs. I have not had to use it so I don’t know if the -2amp hours makes a big difference. I don’t have the 24 volt cord for the ResMed, so I’d be back on the (recalled) PRS1 in a storm.

A friend of mine uses the lithium ion battery sold as CPAP backup (or UPS) power. He leaves his CPAP plugged in through the battery all the time, as his neighborhood has frequent short outages. The battery is plugged into the wall all the time.

Good luck!

- SleepyCPAP

It's irking that people are mentioning car batteries to the OP. If he is going to buy a battery solely for CPAP backup, he should not choose a car battery.

Hi. Thanks for the replies. I have two machines.Airsense 10 and old Respironics Remstar Pro Legacy I can use either but I predominately use Resmed's Air Sense 10 and the pressure goes up to 12. And yes, I would like to use a 150 watt DC adapter.

@ChicagoGranny, what do you suggest if not a car battery? It seems people have been successful with them in the short term and it seems like the least expensive and hassle-free option. If it's complicated, I won't do this. I can always stay at a motel which would be cheaper.

Justin Case said:

I can always stay at a motel which would be cheaper.

I tried that once. The hotels were full. Everyone had that same idea during the power outage - plus all the electric repair crews and tree removal crews were flooding the area and taking up rooms. There weren’t rooms left for me.

ChicagoGranny said:

If he is going to buy a battery solely for CPAP backup, he should not choose a car battery

Agreed. Offgassing hydrogen, could spill acid, bulky and heavy. Can’t be drained past 50% or it gets damaged.

I’ve been told glass mat batteries can be drained to 80% before that same damage occurs (what’s in my jump starter, and the stand-alone battery I have now which may be for a wheelchair). The Lithium Ion batteries are better at this, and more than one night.

Justin Case wrote: ↑

Sat Aug 21, 2021 2:34 pm

Hi. Thanks for the replies. I have two machines.Airsense 10 and old Respironics Remstar Pro Legacy I can use either but I predominately use Resmed's Air Sense 10 and the pressure goes up to 12. And yes, I would like to use a 150 watt DC adapter.

@ChicagoGranny, what do you suggest if not a car battery? It seems people have been successful with them in the short term and it seems like the least expensive and hassle-free option. If it's complicated, I won't do this. I can always stay at a motel which would be cheaper.

from another thread, pugsy suggests-

Pugsy wrote: ↑

Fri Aug 13, 2021 11:43 am

I would look at a deep cycle scooter (wheelchair, power scooter, gold cart) type of battery if it were me and the appropriate connectors or clips.
35 Ah size would likely last 3 nights with no heated hose or humidifier to drain it.

Cheaper than the lithium batteries for sure.

I have no idea how it compares to a jump start kind of battery thing.

Marine batteries are deep cycle as well but with extra "padding" built in to help protect it from the roughness of boats bouncing around on the water...they are usually more expensive than the scooter batteries. You don't need the extra "padding".

eta: another thread, palerider tells why car batteries are, and you should pardon the expression, non-starters.-

palerider wrote: ↑

Sun Aug 08, 2021 2:19 pm

Tony415 wrote: ↑

Sun Aug 08, 2021 1:56 pm

I am sorry If you think my recommend is bad. So you should not use the car starter battery for running CPAP machine when going camping out door. I just want to share my thought. Have a nice day to all.

No, using the starter battery in a vehicle is always a bad idea. The batteries aren't designed for that, they're designed to give a quick burst of energy and be immediately recharged.

How many times have people left a light on in the car and come back to a battery that can't even start the car?

If someone wants to do car camping, get a deep cycle battery and then recharge it however, that's a vastly superior method.

put "scooter battery" in the forum search function and read for your self.

good luck!

ChicagoGranny wrote: ↑

Sat Aug 21, 2021 11:50 am

It's irking that people are mentioning car batteries to the OP. If he is going to buy a battery solely for CPAP backup, he should not choose a car battery.

I would only use a car battery or whatever was available to you if there was no other choice. But if planning ahead I would choose first what I have on hand so I could try it ahead of time which should be done when planning.

The first thing you will need is the correct 12V cable for your cpap. The Re$med cable converts 12V to 24V for use by the re$med cpap. So you will need to know the make and model of your cpap when ordering the cable. If in doubt call them to ask....
https://www.cpap.com/plp/cpap-power-cords/ZT0zMTE

If shopping both the car jump starter and the scooter batteries are a good choice. IMO the car jump starter is a good choice if you are not good with wires, understanding electronics, or electronic toys. Reason is it comes already assembled, with a carry handle, and the USB and 12V outlets you need to plug your cpap into. So it's just Plug n Play.

The more Amp Hours (AH) the battery has the longer it should last, the more it will cost, and the more it will weigh. That is until you get to lithium.

IMO the lithium batteries are good if money is no object but weight is. They do make lithium jump start batteries but I've not experimented with the one I have yet because I have other options.

Make sure to charge any new battery before use and again after use. Be sure to read any user manual it comes with.

SleepyCPAP wrote: ↑

Sat Aug 21, 2021 10:18 am

Supposedly it can be recharged plugged into the car’s 12v socket too, but I don’t have that cord (car charging is supposed to be faster too).
If you have the jump starter mentioned below - I believe that cable comes inside of the little compartments. Take a look.

https://www.cpaptalk.com/viewtopic.php?t=64943

Although not as good as a true deep cycle battery, the marine deep cycle battery I bought today was easy to get and cost me $120. A true deep cycle battery would probably have cost 2 to 3 times that much. It should get me through the storm thats hitting tomorrow. The pinout on the resmed 24 volt adapter does not appear to be very standard, the 24 volts is from the inside barrel to the outside barrel. The center pin has about 3.3 volts on it, not sure why, but its the same as the resmed ac adapter. I could not get a genuine Resmed 12 to 24 volt dc converter quickly, but the Chinese nock-off from Amazon appears to work ok. I have only been on the Resmed machine for a week, i had not had time to gather the genuine adapter yet.

Resmed has excellent info for download about battery draw for their machines and various configurations. Without the heated tube and humidifier, i will easily use only a small fraction of the battery capacity each night. It should be quite safe for the battery. It actually looks like i could even use the humidifier on a low setting if i need it.

Jim

jim22 wrote: ↑

Sat Aug 21, 2021 7:11 pm

the marine deep cycle battery I bought today was easy to get and cost me $120. A true deep cycle battery

What size AH is it?

jim22 wrote: ↑

Sat Aug 21, 2021 7:11 pm

The center pin has about 3.3 volts on it, not sure why, but its the same as the resmed ac adapter.

Has to be the same as the AC adapter or it won't work. the 3.3V is so you don't make your own cord and re$med can charge you 3x the price thats all. Ask why they made it 24V instead of the 12V that is found thruout the US and on most other cpaps on the market today.

Justin Case wrote: ↑

Sat Aug 21, 2021 2:34 pm

I can always stay at a motel which would be cheaper.

That's my kind of backup!

SleepGeek wrote: ↑

Sat Aug 21, 2021 7:23 pm

jim22 wrote: ↑

Sat Aug 21, 2021 7:11 pm

the marine deep cycle battery I bought today was easy to get and cost me $120. A true deep cycle battery

What size AH is it?

jim22 wrote: ↑

Sat Aug 21, 2021 7:11 pm

The center pin has about 3.3 volts on it, not sure why, but its the same as the resmed ac adapter.

Has to be the same as the AC adapter or it won't work. the 3.3V is so you don't make your own cord and re$med can charge you 3x the price thats all. Ask why they made it 24V instead of the 12V that is found thruout the US and on most other cpaps on the market today.

The battery is not marked with Ah. This one is a Diehard Silver group 27CD, and other similar batteries claim to be 80 to 85 Ah. It it best not to drain it all the way down, i figure it should be ok to use about 50 Ah between charges, but i'm mostly making that up, not really sure.

ChicagoGranny wrote: ↑

Sat Aug 21, 2021 8:00 pm

Justin Case wrote: ↑

Sat Aug 21, 2021 2:34 pm

I can always stay at a motel which would be cheaper.

That's my kind of backup!

IF they have power.

Ain't nuttin like sleepin right thru a storm tho.

jim22 wrote: ↑

Sat Aug 21, 2021 7:11 pm

Although not as good as a true deep cycle battery, the marine deep cycle battery I bought today was easy to get and cost me $120. A true deep cycle battery would probably have cost 2 to 3 times that much.

A "true deep cycle" battery would have cost less, whenever they slap the label "MARINE" on something, they raise the price, because a "marine" battery is built sturdier (with no added capacity) so that they aren't destroyed with the pounding that they get in a marine environment, ie, boats.