Marine battery versus battery pack?

Anyone have experience to share about whether a marine battery or a battery pack works best with an M Auto, which is more convenient, which gives a longer use time, other things I may not have thought about? We occasional take the RV to places that don't have power. I bought the doohicky that has the cigarette lighter and the ends for a battery, but my husband says our generator wouldn't support the CPAP all night (plus there's no cigarette lighter anywhere near the bed), so it looks like I either have to invest in a marine battery or battery pack like those sold on cpap.com. Looks, though, like the cheaper ones ($269) only would last about seven hours so wouldn't last a whole weekend of camping and the super batteries that provide 20 hours are $450, which hits a little at my "cheap button". How long would a marine battery last for an APAP range of 10-14, if anyone knows? And (typical dumb woman question -- sorry), do those have just so many hours of battery life to them or do you have to charge them in some way, too?

Thanks for your input!

Peggy

From what I've read... a CPAP device will consume between 1 amp and 3 amps while it operates... the higher the pressure, the more current it consumes. Current times voltage equals power... There are a variety of ways that battery capacity is measured, sometimes in watt hours, sometimes in Amp hours or miliamp hours... If a 12 volt CPAP machine consumed 2 amps while operating, it would consume 24 watts every hour(watt hour)... or 2 amp hours if you want to quantify it in Amp hours... multiply that times the number of hours you sleep and you have your total nightly needs... Lets say it's a 8 hour night at 2 amps average... that's 16 amp hours, or 192 watt hours.

There are batteries made with Lithium ION technology which have very high power to weight ratios (puts out more power per unit of physical weight) such as the battery geek CPAP batteries. These batteries are very expensive... The largest one they sell is 444 watt hours, at 12 volts, that's the same as 37 amp hours... That battery weights 9 pounds... It costs $750 (possibly cheaper somewhere, but that's what they wanted at the first couple sites I looked at). At $750, this is about $20 per amp hour capacity. That battery could potentially last you a couple nights before needing to be charge... One thing you should be aware of before you consider a battery like this... the capacity available will decrease over time even if you never use it. Some internet sites say you could loose as much as half it's original capacity in as little as three years. If that's true, 3 years from now, you'd be doing good to get one full night of use from a battery like this before needing to recharge it. How fast this happens depends on the storage conditions and such, so your results may vary... Just also keep in mind that the one you buy may have sat on the shelf for some time and may already have lost some of it's capacity...

Marine and/or Deep cycle batteries... They don't have a unlimited life either... but they are nowhere near as expensive as the Lithium ION battery packs... They are HEAVY (made out of lead)... However the total capacity is higher... The smallest deep cycle batteries have at least 50 amp hours, some as high as 200 amp hours or close to that... The higher the capacity, the heavier and bigger they will be... However, these will be the most economical way to get 'portable' battery power for 12 volt devices... Figure on about $1 per amp hour capacity maybe $2/amp hour for a expensive one... You can probably get close to 4 nights on the smallest of your typical deep cycle batteries. I don't have any details on how much capacity these may loose over time, however I'm pretty confident it is nowhere near as rapid as it is for the Lithium ION batteries... Even if it is that rapid a loss of capacity, it's still a heck of a lot less expensive...

In my humble opinion... if traveling mostly by car or RV, or boat for that matter... Lead acid deep cycle is the cheapest way to go... probably also the easiest to deal with in terms of charging methods... Most RVs have deep cycle batteries installed in them already... if you need to supplement that due to your CPAP gear, it's probably still easiest to carry along another deep cycle battery...

The only way I would even consider investing in Lithium ION technology is if I needed to carry the battery with me by hand and/or on my back, etc... For instance... I occasionally fly to Taiwan to visit family... The flight is roughly 18 hours from Detroit to Japan (then another 5 hours on to Taiwan). If I want to sleep and/or use CPAP on the plane, Lithium ION may be the best way to go, due to the weight advantage.... Even so, I probably only make that flight once ever two years... and spending $750 for a battery to make that flight more enjoyable is a lot of money... I might be better off buying a first class set and just plan on staying awake the whole time...

[quote="pjwalman"]Anyone have experience to share about whether a marine battery or a battery pack works best with an M Auto, which is more convenient, which gives a longer use time, other things I may not have thought about? We occasional take the RV to places that don't have power. I bought the doohicky that has the cigarette lighter and the ends for a battery, but my husband says our generator wouldn't support the CPAP all night (plus there's no cigarette lighter anywhere near the bed), so it looks like I either have to invest in a marine battery or battery pack like those sold on cpap.com. Looks, though, like the cheaper ones ($269) only would last about seven hours so wouldn't last a whole weekend of camping and the super batteries that provide 20 hours are $450, which hits a little at my "cheap button". How long would a marine battery last for an APAP range of 10-14, if anyone knows? And (typical dumb woman question -- sorry), do those have just so many hours of battery life to them or do you have to charge them in some way, too?

Thanks for your input!

Peggy

Cheap and heavy wins out!! Thank you all very much for your input!!!!!

Peggy

pjwalman wrote:Cheap and heavy wins out!! Thank you all very much for your input!!!!!

Peggy

The heavier the better unless you have to tote it. A big heavy may last a week, at least 5 nights. Jim

Goofproof wrote:

pjwalman wrote:Cheap and heavy wins out!! Thank you all very much for your input!!!!!

Peggy

The heavier the better unless you have to tote it. A big heavy may last a week, at least 5 nights. Jim

Also look at the information on batteries under the Big Red ? (CPAP FAQ) and there are also a lot of links by Rested Girl there on this subject!

Since when I lose power I tend to lose it for an extended period I went with heavy......
Heavy will power my APAP for a week (about 5-7% charge per night), and I can always hook the charger to the generator if necessary.

All that said, I sure wouldn't want to be hauling around my solution. If I was going to need portability, I'd definitly go with the smaller unit, even though it's more expensive. My issue with that, is charge cycles and requirements.... I don't want to have to charge it every day.

If it's in an RV just for sleeping, find the smallest Deep Cycle battery you can find, put it in a "box" (I got a plastic box for mine since it's in the bedroom), set up the wiring and go for it......

I had one miserable night without xPAP during the first power outage this last winter (7 days), so......Don't want to do that again. (As an aside, it's the only red mark on my reports anywhere and is the only blemish in otherwise 100% compliance).

Have fun -- Good luck
cheers
goose

Goose, you had a seven-day power outage??? Good Lord, that must have been a booger to get through! Were you lucky enough to have a fireplace or woodstove? I can't even imagine that. Bet you caught up on your reading, huh?

Peggy

I have both; a heavy RV (not marine) deep cell that will last maybe a week and a portable li-ion CPAP battery that will last one, maybe two nights. The CPAP battery can be stashed in a CPAP bag and it can be taken on an airplane. The RV battery can be moved if it has to be moved.

When I use my autoM, I power it directly from the CPAP battery (which has its own brick charger). I don't have to use the Respironics brick, and if the power fails the CPAP just keeps on working.

When I use my IntelliPAP, it is plugged into both the CPAP battery and the AC power; when the AC power fails, the IntelliPAP automatically switches to battery power.

[quote="ww"][quote="pjwalman"]Anyone have experience to share about whether a marine battery or a battery pack works best with an M Auto, which is more convenient, which gives a longer use time, other things I may not have thought about? We occasional take the RV to places that don't have power. I bought the doohicky that has the cigarette lighter and the ends for a battery, but my husband says our generator wouldn't support the CPAP all night (plus there's no cigarette lighter anywhere near the bed), so it looks like I either have to invest in a marine battery or battery pack like those sold on cpap.com. Looks, though, like the cheaper ones ($269) only would last about seven hours so wouldn't last a whole weekend of camping and the super batteries that provide 20 hours are $450, which hits a little at my "cheap button". How long would a marine battery last for an APAP range of 10-14, if anyone knows? And (typical dumb woman question -- sorry), do those have just so many hours of battery life to them or do you have to charge them in some way, too?

Thanks for your input!

Peggy

pjwalman wrote:Goose, you had a seven-day power outage??? Good Lord, that must have been a booger to get through! Were you lucky enough to have a fireplace or woodstove? I can't even imagine that. Bet you caught up on your reading, huh?

Peggy

Yeah Peggy -- 7 days is about average for our area. We're "at the end of the road" so if there's an outage, we're generally last restored. Goes with the territory. This past January's storm was a bear and our power company did a bang up job of getting us all restored as quickly as they did -- one worker was electrocuted in the process -- God bless him!!!

We heat with wood and our hot water is propane, so the only thing we really did without was cooking (electric stove/oven). Once I go back to work we're going to covert that to gas as well. (Cooked on top of the wood stove)
We do have a generator so that helped, but a power surge from the generator destroyed the motor in our refrigerator so we lost all of our cold food -- even in the freezer. It became an exercise of shopping each day for what we were going to eat that day or emptying out the cupboards of stuff we already had.....
Most of the time the generator was on the "entertainment center" and the fish tank so we had happy fish and we could at least watch the boob tube (satellite TV).....

Just another week in the country!!!

Take care
cheers
goose

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I'm impressed, Goose! I know we wouldn't have been nearly as prepared, and it gives me food for thought about the generator. We would have to do without hot water, but I guess we could stand to be stinky a few days . I can't imagine living a week listening to my 12-year-old whine about not being able to play his Xbox Live, though. And I work out of my home, so I would be sunk without a way to power everything up. Hmmm. Maybe I better check into generators one of these days.

Sounds like you are a wonderful example of "If life gives you lemons, make lemonade." I love that!

Peggy

Ha....And don't put sugar in the lemonade!!!!!

When considering a generator try to make sure you size it properly -- to do over again, I would have bought a bigger one....Mine is 3500W and I would have got at least a 6500W. I hadn't planned on running the whole house - just the things necessary, but in retrospect, running the whole house isn't a bad thing.
I think it's Vader that has a whole house system that is a shining example of how it's done if you have the $$$....
(Also in retrospect, I would have gone diesel instead of gasoline!!! With a diesel generator I could run it on vegetable oil at about $2.00 to $2.50 a gallon (or less)!!!! Buy it by the pallet at Costco!!)

Look at your utilization. Add it all up (fudge about 25%) and size your generator appropriately. Don't forget the phantoms in the system (usually the only time you worry about them is if you're setting up an alternative system -- photo voltaic or wind, or....). Not important in an "emergency" system, but always a good idea to know where your phantoms are -- TV's, VCR's, Clocks, coffee pots -- things that are turned off and still draw power.

Good luck!!!
cheers
goose

I went heavy too - I have a 105ah deep cycle battery, and can manage about a week on that. It's not something for your backpack, and it's a weight to pack for a camping trip, but it's worth it knowing that it will do the job and more.

The thing to remember with lead acid batteries (even the deep cycle ones) is that what kills them is being totally discharged. If they are used within limits (about 90% of charge for a car battery, 50 - 75% for a deep cycle) they will last a very long time, but if they are discharged completely before recharging, they will die quite quickly.

I'm planning a 5 day hike in September here, and due to weight constraints (and general fitness levels) will most likely have to 'go commando' for the trip. This worries me, as it's risky, but it worries my wife more, as I might just get a little 'alert' after 4 nights with poor sleep.

Colin

Hey Colin,
You have time!!! Look into a lightweight solution that can be charged with a solar panel. There are some realllllly light weight, fairly small solar panels these days that may just fit outside a backpack (or even on a hat!!!) so that it can charge the battery while hiking....There are some battery packs out there that only weigh a couple pounds -- there may be a solution for you out there somewhere......

Just a thought!!!
Good luck!!
cheers
goose