esimmers
Senior Member
- Joined
- May 15, 2010
- Messages
- 170
Want to use a CPAP machine in your FWC at night to help you sleep? I thought I'd share what I have learned from powering mine with my FWC's factory-size house battery.
Main Takeaways:
1. Make sure your CPAP machine will run on 12 volts DC, the same voltage as your battery.
2. Power your machine directly from your battery; don't use an inverter and wall adapter.
3. No heated humidifier, the heating element uses just too much electricity.
With these tips, you could probably run a CPAP by itself for a week from a camper house battery. Of course, you will also be using your house battery for lights, the refrigerator, etc., but this gives you an idea about how easy it is to power a CPAP machine with your current system if you're reasonably careful.
First: Make sure your CPAP machine runs on 12 volts.
Find a new or used CPAP machine that is powered when home by one of those external power bricks that output 12 volts DC. These machines are easy to find although some newer machines are switching to 24 volt power bricks that we can't use. Lots of info online for setting the right breathing pressure once you find a machine.
Second, power your machine directly from your battery; don't use an inverter and wall adapter.
You wouldn't pay double for gas for your truck, why pay double for electricity from your battery to power your CPAP machine? You will use at least twice as much electricity from your battery if you use an inverter and the wall adapter you use at home. All the wall adapter does is to convert 120 volts AC to 12 volts DC. Doesn't make sense then to use an inverter to make 120 volts AC from your 12 volt DC battery. You can purchase a power cord with a 12 volt cigarette lighter plug on one end and the 12 volt CPAP fitting on the other. The CPAP manufacturers sell them although you can find them cheaper online or your local electronics store.
Finally, don't try to run a heated humidifier.
Humidifiers contain a heating element to heat the water in the tank so it humidifies the air you breath through the CPAP hose. Heaters take a HUGE amount of energy to work; you'd be lucky to get one full night out of a camper house battery using a humidifier turned on high.
______
I hope this info is helpful. For your information, I tracked the energy used by my CPAP setup powered directly from my 12v battery: about 5-6 amp hours for one full night. Most house batteries are rated 80-100 amp hour capacity but you shouldn't run them down more than half way. So 40-50 amp hours is all you want to pull from your house battery without damaging it. That's 6-8 nights, optimistically, if you didn't use the battery for anything else (not likely).
You probably have some solar power or charge your battery when driving. So figure a night's worth of CPAP machine runs your battery down 10-20%. That gives you a general idea about how much juice you need to restore to your battery each day to keep it topped off.
Main Takeaways:
1. Make sure your CPAP machine will run on 12 volts DC, the same voltage as your battery.
2. Power your machine directly from your battery; don't use an inverter and wall adapter.
3. No heated humidifier, the heating element uses just too much electricity.
With these tips, you could probably run a CPAP by itself for a week from a camper house battery. Of course, you will also be using your house battery for lights, the refrigerator, etc., but this gives you an idea about how easy it is to power a CPAP machine with your current system if you're reasonably careful.
First: Make sure your CPAP machine runs on 12 volts.
Find a new or used CPAP machine that is powered when home by one of those external power bricks that output 12 volts DC. These machines are easy to find although some newer machines are switching to 24 volt power bricks that we can't use. Lots of info online for setting the right breathing pressure once you find a machine.
Second, power your machine directly from your battery; don't use an inverter and wall adapter.
You wouldn't pay double for gas for your truck, why pay double for electricity from your battery to power your CPAP machine? You will use at least twice as much electricity from your battery if you use an inverter and the wall adapter you use at home. All the wall adapter does is to convert 120 volts AC to 12 volts DC. Doesn't make sense then to use an inverter to make 120 volts AC from your 12 volt DC battery. You can purchase a power cord with a 12 volt cigarette lighter plug on one end and the 12 volt CPAP fitting on the other. The CPAP manufacturers sell them although you can find them cheaper online or your local electronics store.
Finally, don't try to run a heated humidifier.
Humidifiers contain a heating element to heat the water in the tank so it humidifies the air you breath through the CPAP hose. Heaters take a HUGE amount of energy to work; you'd be lucky to get one full night out of a camper house battery using a humidifier turned on high.
______
I hope this info is helpful. For your information, I tracked the energy used by my CPAP setup powered directly from my 12v battery: about 5-6 amp hours for one full night. Most house batteries are rated 80-100 amp hour capacity but you shouldn't run them down more than half way. So 40-50 amp hours is all you want to pull from your house battery without damaging it. That's 6-8 nights, optimistically, if you didn't use the battery for anything else (not likely).
You probably have some solar power or charge your battery when driving. So figure a night's worth of CPAP machine runs your battery down 10-20%. That gives you a general idea about how much juice you need to restore to your battery each day to keep it topped off.
