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greatunclebill wrote:so, do the cpap's draw enough juice to drain the car battery overnite? i ask this because i'm wondering if the lawn mower 12v battery thats like a little car battery would handle the load. its on a 16.5 hp craftsman 42" cut.

Most XPAPS draw under 2 amps, so you run 2 that's 4 amps per hour. You should get 1 to 2 night on the car battery powering both xpaps. I would use a second battery socket plug rather than to "Y" them as sometimes the size of the wire can cause a voltage drop. Also the battery being 14 volts isn't a problem, the 14.4 to 14.8 volts is need to charge the battery, without the charger on the battery it just creates a surface charge, that drops quickly in use, most electronics have a spec of +/_ 10%. If you did use diodes to provide a voltage drop, they would also limit the time the XPAP's could run before they shut down from low voltage. The mower could be used for power too @12 volts. Jim

Biggest problem with most conventional batteries is that they are not designed to last during deep discharges. It's a great way to turn them into very expensive paper weights. A deep cycle battery (of some variation) is a better choice.

I ran some tests on my setup back in early July when the Dericho hit us here in VA. I got two full nights off of my Jump Start battery and the voltmeter barely budged off of 13+ volts. Of course, no heated humidifier (which I never use anyway). Didn't try a third night.

OH my gosh. No way am I gonna try this. Congrats on making it work, but this is beyond my skill set.

That said, do you have recommendations for a battery to purchase? I didn't do any research when they gave me my machine (only had it for a month now... didn't find this forum till after I got it), but I do want to be more proactive in buying a battery. Any recommendations for specific models or where to look?

I'm in earthquake country, and have a job where I need to respond in disasters, so I've got to make sure that I can SLEEP!

greatunclebill wrote:so, do the cpap's draw enough juice to drain the car battery overnite? i ask this because i'm wondering if the lawn mower 12v battery thats like a little car battery would handle the load. its on a 16.5 hp craftsman 42" cut.

One CPAP with humidifier, probably. When I tried it once with my S9 w/ humidifier the battery died after about 6 hours, but it was a few years old too. Forget the lawn mower battery. It won't last long enough to be worth the bother. I'd be surprised if you can get more than two nights out of the car battery if two CPAPs w/o humidifier are running off it.

Be sure to have a backup way to start the car if you do use the car battery and run it down. Your best approach would be to go buy a 100+ amp hour deep cycle battery. They're $80 at Costco.

eaglett1111 wrote:OH my gosh. No way am I gonna try this. Congrats on making it work, but this is beyond my skill set.

That said, do you have recommendations for a battery to purchase? I didn't do any research when they gave me my machine (only had it for a month now... didn't find this forum till after I got it), but I do want to be more proactive in buying a battery. Any recommendations for specific models or where to look?

I'm in earthquake country, and have a job where I need to respond in disasters, so I've got to make sure that I can SLEEP!

So what did you do -- just skip over my post? THERE IS NO SIMPLER BATTERY HOOKUP than what I recommend. Again, I got two full nights and it still had plenty of battery left.


Battery Back-up: http://www.cloreautomotive.com/sku.php?id=244

Power Cord: http://www.cpapsupplyusa.com/DC-12-Volt ... 01956.aspx