Just a point here.
Don't travel with a lead acid motorcycle battery. Heavy and must remain upright. There are many suitable Gel Cells out there with the voltage and current capacity you need. Even though your power supply says it will give you 2.5 amps at 12 volts DC, you need to research your actual CPAP and what settings you use. Some will actually use less than an Amp and your sizing requirements can be very much altered from settings that actually use more current. I am a CPAP user and I have options for heated vapor on my humidifier and I use a rather high pressure setting. (BAD SINUSES, BAD) Most motorcycle batteries are rated at about 12 AMP hours. Drawing an actual 2.5 AMPs at 12Volts DC would mean the battery is really a one night unit. If your actual draw is about an amp, that same battery will most likely last the three day trip. Solar chargers are good but pricey, Solar power is not really worth $69 for a 13 watt charger. You can pick up a 40 watt panel for not much $$$ and make your own. I have a Solar power system on my house and I Love the cheaper electric bills and I know I am least doing my part. Check out any of the ZILLIONs of web resources for panels even eBay and you can set up a charger in a heartbeat. Much more capacity and not much money. Get a Gel Cell with tabs and set up the DC supply to just plug and go. I have several "lay around" panels from 20 to 240 Watt laying around. I have tried several types and layouts until I settled on my large array. Check eBay for whatever you feel you need. Ed From: Geary Schindel [mailto:gschin...@edwardsaquifer.org] Sent: Sunday, November 18, 2012 10:38 AM To: texascavers@texascavers.com Subject: [Texascavers] electronic question - help requested Folks, Sue and I are heading out camping this Thanksgiving and have a camping/caving related question for the electronics gurus in the group. Sue has a sleep apnea machine she uses. We've used a marine battery that has worked for as long as a week without charging. I checked the amp hour rating of the battery and compared it to the demands of the machine but I'm not sure I got it right or was just lucky. On this trip, we're flying out to meet Graham and Aspen and going camping in Deaf Valley - That's Death Valley, just checking to make sure you're listening. Flying with a 70 pound marine battery probably isn't a good idea. Anyway, we were thinking of purchasing a motorcycle battery from Autozone in a nearby town and was wondering if folks think the battery would last for three nights without charging. We use an inverter connected to the battery to power the machine. The machine is a Resmed. The specs are AC 100-240V 50-60 hz. 110v 400 hz, 2.5 a. DC 12 V 2.5 amp. I didn't see the DC connection before so I'm wondering if I can get a 12 volt DC cord. Anyway, I'm not familiar with motorcycle batteries and don't know whether they are 12 v or 6 volt and how many amp hours they are. Anyone have some suggestions as to what they do. Thanks Geary, P.S. if you're thinking about breaking into my house and robbing me of my vintage caving coveralls with real canvas grip patchs (a real collectors item), we will have a full time housesitter and visiting friend.
