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Battery performance experiment
#1
OK - So we had a power failure just before the big ice storm a week and a half ago. With the storm threatening, I decided to be ready to use standby battery system, should the power system take a dump.

So I unhooked the S-9 Autoset, brought in the Intellipap Auto that I picked up for next to nothing at a pawn shop (and less than 25 hours total time!), trundled out one of the 39 AH AGM batteries, hooked it up and went to sleep. The power was off for a few hours and the Intellipap switched over to AC as soon as it came back on during the night; I never woke up.

But I was curious. So, the next night, I went all battery - no AC. I started with a 39 AH AGM battery that had been sitting a month since it was charged - half-way into the bimonthly battery charge cycle (I charge them every two months, on the first of each odd-numbered month).

It started out at 13.06V. I ran it an average of 7-7.5 hours a night for six full nights. It was at 12.10 V at that point, and I didn't want to run it down past 12. Could probably gone another couple of nights. Charge would drop about 0.17V after each night's run. I figure with a more common, but physically comparably sized 35 AH battery, I would probably subtract one, maybe two nights.

That is running with a setting from 8.0-15 cm H20 - my average last time I checked the Resmed S-9 against Sleepyhead or ResScan was probably around 10.5-11.0 cm H2O. That is without any heated humidification, but with the Intellipap, passive humidification is easy on battery. The machine just doesn't power the heating plate but will blow across the water in the tank.

So I was very happy with that. I figure with two of these batteries and a smaller one in the rotation, I would have plenty of juice to run for two weeks without power and would be able to use this system indefinitely with a solar charger. I was considering the Resmed DC converter in that the S9 would draw significantly less amperage than the Intellipap, and I would probably get 2-3 more nights, but I see no need to spend that $85-100 for the converter now.

This is running straight from the battery into the 12V plug on the back of the unit. No converter necessary. And, God no, NEVER an inverter if going for duration.

YMMV. If it were at the end of the bimonthly charge cycle, I would probably expect to trim a night off to allow for that.

Note that this was a relatively new battery (about 6 months old) that has a pretty good maintenance regimen. I would expect after a few years, I would probably cut my estimates by a couple of nights, but that's still pretty good.

OMM
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#2
That is good news.

I need to get some new batteries. I think mine are a bit too old to carry the load. I need to experiment I think. (rubs hands together and cackles like mad scientist....)
PaulaO2
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Breathe deeply and count to zen.

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.




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#3
I'm a little confused. I plan on doing some camping and am interested in battery power for my S9 autoset. I'm unfamiliar with the battery types you mentioned, but I've been reading up on them. Do I understand that you should not use a power inverter? Will my S9 run on 12 volts? Is there any combination of lithium batteries that would work? Lithium, are stronger, lighter and hold their charges many times greater than any other type.

Could a person build a battery pack of rechargeable Lithum batteries?
I know I am full of questions.
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#4
(12-17-2013, 07:55 PM)drgrimes Wrote: I'm a little confused. I plan on doing some camping and am interested in battery power for my S9 autoset. I'm unfamiliar with the battery types you mentioned, but I've been reading up on them. Do I understand that you should not use a power inverter? Will my S9 run on 12 volts? Is there any combination of lithium batteries that would work? Lithium, are stronger, lighter and hold their charges many times greater than any other type.

Could a person build a battery pack of rechargeable Lithum batteries?
I know I am full of questions.

ResMed S9 machines require the overpriced ResMed DC-DC converter or you can use an inverter. The converter is probably more efficient and the battery will last longer.

Don't screw around with making your own lithium battery packs. Lithium batteries sort of want to explode and if you combine then or make your own adapters/chargers, there is a much greater chance of fire/explosion or triggering the protection circuitry in some lithium battery packs and having it simply quit working all at once with no advance warning.

You generally want a commercially designed lithium battery pack and the manufacturer's charger.
Get the free SleepyHead software here.
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Click here for information on the main alternative to CPAP.
If it's midnight and a DME tells you it's dark outside, go and check it yourself.
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#5
A power inverter, one that say, you plug into the cigarette lighter in the car and it has a regular 110v plug for your laptop, you lose a lot of power that way. It will cut the battery usability drastically.

There's a battery kit you can get that includes the battery and everything you need except for the adapter doohickey that goes from plug to plug. This is not included because it can be used with various machines.

I think that adapter doohickey can be used between the S9 and any 12v system.
PaulaO2
Apnea Board Moderator
www.ApneaBoard.com


Breathe deeply and count to zen.

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.




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#6
Don't the ResMed machines run on 24 volts DC?

DrGrimes, when camping will you be carrying your battery, or will you be within walking distance of your vehicle? The reason I ask is that lead acid batteries will give you more bang for your buck, but lithium ion will be much lighter and more compact for carrying.
Sleepster
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INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
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#7
(12-17-2013, 07:55 PM)drgrimes Wrote: I'm a little confused. I plan on doing some camping and am interested in battery power for my S9 autoset. I'm unfamiliar with the battery types you mentioned, but I've been reading up on them. Do I understand that you should not use a power inverter? You understand. Will my S9 run on 12 volts? Not straight from the battery. Is there any combination of lithium batteries that would work? Probably. Lithium, are stronger, lighter and hold their charges many times greater than any other type. Um, depends on what they are used for - for deep cycle applications like this, I **personally** tend to think I would prefer SLA. SLA is cheaper for the energy output than LiIon. SLA you can carry on a plane as it's not considered "hazmat". There are sometimes restrictions on carry of LiIon-restriction may only be forbidden in checked bags? They don't look favorably on shorts and fires in the baggage hold?

Could a person build a battery pack of rechargeable Lithum batteries?
I know I am full of questions.

You need to know how long you will be out camping (nights) and what the power consumption for the S9 is with your settings. It can be found at:

http://www.resmed.com/assets/documents/s...lo_eng.pdf

The battery types I mention are the absorbed glass mat (AGM) or they are also called sealed lead acid (SLA) batteries.

The 35-39 amp hour (AH) batteries are about 20-22 lbs. An 18 AH probably weighs 12-13 lbs. At 11 cm H2O, where my pressure averages, it says I would need a 7 AH battery for an 8 hour night - and that includes a 50% reserve for varying conditions (battery condition, age, temperature, etc.) For two nights, I would need a 14 AH battery. For three nights, a 21 AH battery. You get the picture.

These are the same batteries that you would use in on of those scooters that they advertise to "mobility challenged" folks on the 2:00 AM infomercials. Sometimes they are used in motorized kids' toy vehicles. I have seen them at some auto parts store (note you would not want to use a starting battery for this purpose). They are widely available online. Googleate or Yahoodle the term "SLA battery" to find them. Specialty battery stores will definitely have them (can I mention brand names like InterPlus or BatteriesState - or some combination of those manes - as examples here?)

The S9, using the ResMed DC converter is amazingly efficient (the native power input for the S9 is actually 24V DC). Its consumption is probably 60-70% of what the Intellipap uses. BUT, you have to use THEIR 12V DC to 24VDC CONVERTER (note that using an inverter is obscenely inefficient (you take 12V DC current, use a bunch of energy to convert it to 110-120V, then use even more energy to turn it back into 24 DC current with the standard power brick on the S9)). The Resmed DC converter is available at several online CPAP suppliers - probably between $85 and $120.

And forget about using the humidification unit. That blows the power consumption sky high too.

OMM
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#8
You might be able to figure something better out for your needs and circumstances, but after checking everything out I went with the ResMed DC/DC converter (comes with everthing needed to hook up from battery to machine...terminal clips to female lighter port, male lighter plug to brick and brick to machine) and a 114ah marine deep cycle battery. I simply cannot go without humidification and this set up will run the machine, humidifier and ClimateLine for one night without fear of discharging so deeply it damages the battery - I charge it most of the next day on auto trickle charger and gas generator to get the next night out of it though. You could get by with lower ah and/or get more nights between charge if you can stand to forego humidification... and AGM battery would be better and last longer, but at higher cost. Still heavy batteries to lug around though...

Something you might already know, but took me a while to realize when I was figuring out what to get. S9 runs on DC, so the regular power brick changes AC house current to DC for the machine. If you get an inverter and hook it up to DC power supply (battery) then plug the wall plug into the inverter, then you are changing DC to AC then AC to DC...two big power wasting processes. With the DC/DC converter kit the power remains DC all the way from the battery to the machine...a much more efficient operation.

Best of luck figuring out what will work best for you!Sleep-well

Edit: If you can go without humidifier, going with lower ah/smaller batteries pointed out by OMM is probably a much better option for you. If I had to guess, I would say my 114ah batteries weigh about 60 lbs each...that's just a guess, but good point of reference for you to consider - they are heavy SOBs and I wouldn't want to carry them very far.
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#9
If you go for the AGM, go for the "marine" ones. If you go for the "wheelchair" ones, you'll be paying a lot more. Same battery, same everything, but medical on the label and the price skyrockets.

My current chair batteries are by MK and ghastly expensive. If I had to pay out of pocket, I'd get the same AH boat battery (usually Interstate brand) from Advance Auto and pay a quarter of the price.
PaulaO2
Apnea Board Moderator
www.ApneaBoard.com


Breathe deeply and count to zen.

INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.




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#10
Thanks everyone for all the good info. Luckily I will not be having to carry batteries. I recently bought a new pop up camper that has a 12V system when i'm not connected to 110ac. I don't know the AH on the battery, but I was told that it is a heavy duty marine type battery.

It looks like all I need is the DC to DC converter to use my existing system. I just didn't want to run completely drain the battery using cpap in the first night. I have a portable Honda generator so I can charge during the day time. It makes good sense that converting from 12v to 110 then back to 24v would be a wasteful process. THANKS!!!
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