DC 12 Inverter

How long does a normal car battery run the machine for with the DC12

PieterSA wrote:How long does a normal car battery run the machine for with the DC12

That depends on the size of the car battery AND the load it is connected to. Too many variables to give a black & white answer.

Generally speaking the larger the amp/hours (ah) the longer it should last. The higher your pressure, the more ah it will take to last the same time period.

FYI
I just found this long 2 part article on CPAP and batteries:
http://www.newtechpub.com/sleep/magazin ... wer01.html
http://www.newtechpub.com/sleep/magazin ... wer02.html

BTW, as I've read elsewhere, the article says you shouldn't use a "car" battery, because they are not designed for that kind of use. You should use a deep cycle battery.

"Don't use a car battery except for very short times because it can be quickly ruined by being drawn down heavily; although if the battery has a high rating and you draw a small portion, you may not notice significant degradation of the battery. You can use an adapter to draw current from the cigarette lighter. This can be a practical solution if you go camping or need to take naps on a long trip. The next time you replace your car battery, consider getting a deep cycle battery which can also serve to start your car. Check with your car manufacturer to be sure that your car's electrical system is suited to this type of battery."

I use a 12 volt deep cycle marine battery and mod. inverter, with my F&P 604 set at 11 and NO NOT use the humidifier. I have gotten four 8 hour nights with this set up.

I have a PR system one and have used it several times with a battery, due to power outages and also when camping. I bought a middle of the road marine battery from sears (80-100 amp-hours? I don't remember exactly). Since my PR system can run off of 12 volts, I bought a direct connect cable so I don't need an inverter.

I have used it for as many as 12 days straight and the battery was down to about 30-40%. My machine averages around 10-12 pressure and I sleep 6-8 hours per night. When using the battery I have the humidifier turned off.

I did a little checking and inverters can be big power hogs when used in applications with low power draws. The efficiency rating on them is for when they are under a heavy load. I suspect the power measurements in the those linked websites probably include the inverter.

A regular car battery will work fine for a night or 2. The problem with them is they don't like being drawn down below 60% power. If you only use a little, then charge it back up then the battery should be unharmed.

Chris

"The next time you replace your car battery, consider getting a deep cycle battery which can also serve to start your car. Check with your car manufacturer to be sure that your car's electrical system is suited to this type of battery."

Most deep cycle batteries aren't designed to provide the high current used for starting a car. You may damage the battery or find it doesn't work well for starting the car. There are "dual purpose" deep cycle batteries, but they are a compromise and don't do either job as well.

In general, a battery design that gives a high starting current won't tolerate deep discharge, and vice versa.