quote:

ORIGINAL: igor2003

Good suggestions from both of you. I'll look into those. I'd still like to find out more about how long one battery might last, though. Most all of any foreseeable camping will be done in my van, but I also belong to an ATV club, and it is very possible that we may ride into the back country for a few days stay at some future point, in which case I would still want to be able to take a power supply with me.

quote:

ORIGINAL: Gauge

quote:

ORIGINAL: igor2003

Good suggestions from both of you. I'll look into those. I'd still like to find out more about how long one battery might last, though. Most all of any foreseeable camping will be done in my van, but I also belong to an ATV club, and it is very possible that we may ride into the back country for a few days stay at some future point, in which case I would still want to be able to take a power supply with me.

You could take a separate battery to use solely for your machine. That way you are not risking your vehicle battery at all. There are solar powered electric generators out there too but they are likely very expensive and might be too much for your specific needs, but could be damn handy for camping and therefore worth the investment.

I did a quick look around to try to find a decent explanation on understanding battery ratings, that it comes from a solar site is simply a coincidence. The very bottom line about a car battery is that you never really want to discharge the battery without replenishing the charge. I really believe that a good solar charger is the way to go. Look for one that will be able to charge even if it is cloudy outside.

quote:

ORIGINAL: igor2003

I have a BiPAP machine (for those that don't know, BiPAP is similar to CPAP, but the air flow fluctuates with your breathing.) that has a DC option, so it can be used during power outages, or for camping, etc. For that, you have to have a 12 volt, DC power supply. It is made to plug into an accessory outlet in a motor vehicle. I want to be able to plug it into a separate system than my van's electrical system, so I'm going to get either a deep cycle, 12 volt battery, or (more likely) a self contained battery booster system. I may want to use it for up to about 5 nights for camping trips, etc..

So...here is the question...the machine draws 3 Amps DC power, so, figuring 8 hours per night, will one battery be enough to last for up to five days use without recharging, or will I need more than one power supply? (More than one battery.)

If I understand it right, you take the total amp capacity of the battery, and divide it by 3 to get the total number of hours that the battery should be able to supply power. That would then be divided by 8 to get the number of nights that the battery should supply power before needing recharged. Does this sound right? (Or just divide the total battery amperage by 24 to get the number of days use.)

I don't want to go on a 4 or 5 night trip, only to run out of power after day one or two, so any information will be much appreciated.

quote:

ORIGINAL: LookieNoNookie

WTF??????

They have a machine that doesn't blow air into your face as if it's a gawdamn reverse vacuum cleaner????? Like having a fucking hurricane running STRAIGHT up your damn nose?

How does it work?

I tried one of those fucking things, went through "sleep trials", pages and pages of data.....all they needed to ask me was..."how do you like that CPAP thingie?"

I fucking HATE IT!!!!...How would YOU like to have a Blow Horn up your nose????

They have a machine that regulates with YOU?????

That breathes as you do?

quote:

ORIGINAL: igor2003
I know about not wanting to discharge automotive batteries, which is why I mentioned using a deep cycle battery.

quote:

ORIGINAL: http://www.solar-electric.com/deep-cycle-battery-faq.html#Lifespan%20of%20Batteries
Battery life is directly related to how deep the battery is cycled each time. If a battery is discharged to 50% every day, it will last about twice as long as if it is cycled to 80% DOD. If cycled only 10% DOD, it will last about 5 times as long as one cycled to 50%. Obviously, there are some practical limitations on this - you don't usually want to have a 5 ton pile of batteries sitting there just to reduce the DOD. The most practical number to use is 50% DOD on a regular basis. This does NOT mean you cannot go to 80% once in a while. It's just that when designing a system when you have some idea of the loads, you should figure on an average DOD of around 50% for the best storage vs cost factor. Also, there is an upper limit - a battery that is continually cycled 5% or less will usually not last as long as one cycled down 10%. This happens because at very shallow cycles, the Lead Dioxide tends to build up in clumps on the the positive plates rather in an even film. The graph above shows how lifespan is affected by depth of discharge. The chart is for a Concorde Lifeline battery, but all lead-acid batteries will be similar in the shape of the curve, although the number of cycles will vary.

quote:

ORIGINAL: LookieNoNookie

quote:

ORIGINAL: igor2003

I have a BiPAP machine (for those that don't know, BiPAP is similar to CPAP, but the air flow fluctuates with your breathing.) that has a DC option, so it can be used during power outages, or for camping, etc. For that, you have to have a 12 volt, DC power supply. It is made to plug into an accessory outlet in a motor vehicle. I want to be able to plug it into a separate system than my van's electrical system, so I'm going to get either a deep cycle, 12 volt battery, or (more likely) a self contained battery booster system. I may want to use it for up to about 5 nights for camping trips, etc..

So...here is the question...the machine draws 3 Amps DC power, so, figuring 8 hours per night, will one battery be enough to last for up to five days use without recharging, or will I need more than one power supply? (More than one battery.)

If I understand it right, you take the total amp capacity of the battery, and divide it by 3 to get the total number of hours that the battery should be able to supply power. That would then be divided by 8 to get the number of nights that the battery should supply power before needing recharged. Does this sound right? (Or just divide the total battery amperage by 24 to get the number of days use.)

I don't want to go on a 4 or 5 night trip, only to run out of power after day one or two, so any information will be much appreciated.

WTF??????

They have a machine that doesn't blow air into your face as if it's a gawdamn reverse vacuum cleaner????? Like having a fucking hurricane running STRAIGHT up your damn nose?

How does it work?

I tried one of those fucking things, went through "sleep trials", pages and pages of data.....all they needed to ask me was..."how do you like that CPAP thingie?"

I fucking HATE IT!!!!...How would YOU like to have a Blow Horn up your nose????

They have a machine that regulates with YOU?????

That breathes as you do?

quote:

ORIGINAL: FelineRanger

quote:

ORIGINAL: LookieNoNookie

WTF??????

They have a machine that doesn't blow air into your face as if it's a gawdamn reverse vacuum cleaner????? Like having a fucking hurricane running STRAIGHT up your damn nose?

How does it work?

I tried one of those fucking things, went through "sleep trials", pages and pages of data.....all they needed to ask me was..."how do you like that CPAP thingie?"

I fucking HATE IT!!!!...How would YOU like to have a Blow Horn up your nose????

They have a machine that regulates with YOU?????

That breathes as you do?

I have had a CPAP for 6 years now and it the only thing I have ever called "a godsend" in my life. Lots of people have difficulty adjusting to the mask and the machine, but I didn't have any such problem. When I had the sleep study done, that was the best I had slept in almost 5 years. But my sleep apnea is just as bad as the one described here, so I was pretty much wrecked by the time it was diagnosed. I hope yours isn't anywhere near tha bad.

BTW, as I understand it, the diagnosis of the type of sleep disorder is what determines whether you get a BiPAP or CPAP. I could easily be wrong.

quote:

ORIGINAL: ThatDaveGuy69

The battery isolator mentioned above is, in fact, called a battery isolator :D
They are used on boats where you have 2 or more batteries. One battery is always reserved to start the engine where the others are used to run the various accessories onboard.
I would not recommend the installation of a 2nd battery to someone asking this level of question - please have it professionally installed. It's not very difficult but if done wrong you'll be out a whole lot more for electrical work.
Also, as mentioned above, this type of job calls for a deep cycle (aka marine) battery. They are designed to be fully discharged and still recover. Car batteries do not like being fully discharged, especially the newer type gell batteries.

Best of luck!

quote:

ORIGINAL: GotSteel

quote:

ORIGINAL: igor2003
I know about not wanting to discharge automotive batteries, which is why I mentioned using a deep cycle battery.

So just to make things more complex for you, how far you discharge deep cycle batteries still matters:

quote:

ORIGINAL: http://www.solar-electric.com/deep-cycle-battery-faq.html#Lifespan%20of%20Batteries
Battery life is directly related to how deep the battery is cycled each time. If a battery is discharged to 50% every day, it will last about twice as long as if it is cycled to 80% DOD. If cycled only 10% DOD, it will last about 5 times as long as one cycled to 50%. Obviously, there are some practical limitations on this - you don't usually want to have a 5 ton pile of batteries sitting there just to reduce the DOD. The most practical number to use is 50% DOD on a regular basis. This does NOT mean you cannot go to 80% once in a while. It's just that when designing a system when you have some idea of the loads, you should figure on an average DOD of around 50% for the best storage vs cost factor. Also, there is an upper limit - a battery that is continually cycled 5% or less will usually not last as long as one cycled down 10%. This happens because at very shallow cycles, the Lead Dioxide tends to build up in clumps on the the positive plates rather in an even film. The graph above shows how lifespan is affected by depth of discharge. The chart is for a Concorde Lifeline battery, but all lead-acid batteries will be similar in the shape of the curve, although the number of cycles will vary.

Maybe you don't do this sort of camping often enough to really care, but if it's a regular basis sort of thing you'll want to oversize your battery bank enough that you aren't discharging past 50%

P.S. The amount of power you can get out of your battery also changed with it's temperature which could be an issue camping certain times of the year.

quote:

ORIGINAL: igor2003


If I understand it right, you take the total amp capacity of the battery, and divide it by 3 to get the total number of hours that the battery should be able to supply power. That would then be divided by 8 to get the number of nights that the battery should supply power before needing recharged. Does this sound right? (Or just divide the total battery amperage by 24 to get the number of days use.)

I don't want to go on a 4 or 5 night trip, only to run out of power after day one or two, so any information will be much appreciated.