Uninterruptible Power Supply for CPAP
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ProfessorSleep
- Posts: 338
- Joined: Sat Sep 10, 2005 7:42 pm
- Location: Wisconsin
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Guest
RE Battery Power:
When it comes down to batteries, believe it or not, your local ham who is interested in disaster services will probably know quite a bit.
In general, there are a few types of batteries we can look at - "Primary" cells - aka non rechargeable, and "secondary" - or rechargeable.
Right away, I'll eliminate "Primary" batteries from the discussion
As for rechargeable batteries, there are lots of choices - You have "exotic" chemistries - (Li-poly etc). there is Ni-Mh, there is Ni-cad, and there is good old Lead-acid
In general, other than the various forms of lead-acid battery are specialized, more expensive, but LIGHTER then lead-acid
Lead-acid is by far the heaviest, but the cheapest and easiest to deal with. Lead acid batteries come in a few types
1)Wet cell - this is the traditional "car" battery where you have to add water - there are advantages to this type of cell, but probably none for anyone here
2)Sealed Lead Acid - These are often referred to as "Gel Cells" which is a trademark for a Gelled electrolyte sealed lead Acid (SLA) battery. There are also "absorbed glass mat" (AGM) batteries, - another form of SLA, and sometimes the end user will NOT draw a distinction. AGM batteries either come in flat plate, or spiral wound (aircraft or "Optima" type)
Another thing to remember about lead/acid type batteries of any type, if they can be designed for 2 different kinds of usage - "Starting" batteries - which are meant to start a car - they are designed to give you a LOT of "cold cranking amps", but are NOT meant to be deeply discharged - if they are, they can be destroyed. The other type - "deep discharge" are meant to supply a lesser amount of current for a longer period of time, and can be brought down to a lower charge level without damage
What this really means is that we are going to be looking for a "Sealed Lead Acid, deep discharge" battery rated for 12 volts
Now, the capacity of these batteries are rated in Amp hours (the number of amps * the number of hours they can supply that current for) - however, there is a "gotcha" - these batteries are usually rated for a 20 hour discharge (called C/20) - Let's say it was a 20 Amp hour (Ah for short) battery - it will deliver 1 amp for 20 hours, but it will NOT deliver 20 amps for 1 hour - you'd be lucky to get 15 minutes out of it (each battery mfg can supply discharge curves if you want)
So, now you have to look at a few things - How much current does your machine draw (I've never measured - so...) - Let's just say 1 amp. You now have to figure out "How long do I want to be able to run my machine?" - now, you might say "Hey, 1 night" - that would lead you to think about a 7Ah battery (so, you sleep a short night), BUT you won't get 7 hours (remember that C/20 rule I told you about?) - You'll probably get around 5. Of course, a 7Ah battery is nice and small - So then you look at a 16Ah battery - or better, a 20Ah - that sounds about right - it's not as good as c/20, - but it'll give you 8 hours, and with an all day recovery, might even give you most of a second night - of course, you can go bigger - I have a few 100Ah+ batteries sitting around, but they are the size of car batteries...
The numbers I gave assumed a 1 amp draw - if it's less, you can live with smaller batteries, if it's more, you need larger
When it comes down to batteries, believe it or not, your local ham who is interested in disaster services will probably know quite a bit.
In general, there are a few types of batteries we can look at - "Primary" cells - aka non rechargeable, and "secondary" - or rechargeable.
Right away, I'll eliminate "Primary" batteries from the discussion
As for rechargeable batteries, there are lots of choices - You have "exotic" chemistries - (Li-poly etc). there is Ni-Mh, there is Ni-cad, and there is good old Lead-acid
In general, other than the various forms of lead-acid battery are specialized, more expensive, but LIGHTER then lead-acid
Lead-acid is by far the heaviest, but the cheapest and easiest to deal with. Lead acid batteries come in a few types
1)Wet cell - this is the traditional "car" battery where you have to add water - there are advantages to this type of cell, but probably none for anyone here
2)Sealed Lead Acid - These are often referred to as "Gel Cells" which is a trademark for a Gelled electrolyte sealed lead Acid (SLA) battery. There are also "absorbed glass mat" (AGM) batteries, - another form of SLA, and sometimes the end user will NOT draw a distinction. AGM batteries either come in flat plate, or spiral wound (aircraft or "Optima" type)
Another thing to remember about lead/acid type batteries of any type, if they can be designed for 2 different kinds of usage - "Starting" batteries - which are meant to start a car - they are designed to give you a LOT of "cold cranking amps", but are NOT meant to be deeply discharged - if they are, they can be destroyed. The other type - "deep discharge" are meant to supply a lesser amount of current for a longer period of time, and can be brought down to a lower charge level without damage
What this really means is that we are going to be looking for a "Sealed Lead Acid, deep discharge" battery rated for 12 volts
Now, the capacity of these batteries are rated in Amp hours (the number of amps * the number of hours they can supply that current for) - however, there is a "gotcha" - these batteries are usually rated for a 20 hour discharge (called C/20) - Let's say it was a 20 Amp hour (Ah for short) battery - it will deliver 1 amp for 20 hours, but it will NOT deliver 20 amps for 1 hour - you'd be lucky to get 15 minutes out of it (each battery mfg can supply discharge curves if you want)
So, now you have to look at a few things - How much current does your machine draw (I've never measured - so...) - Let's just say 1 amp. You now have to figure out "How long do I want to be able to run my machine?" - now, you might say "Hey, 1 night" - that would lead you to think about a 7Ah battery (so, you sleep a short night), BUT you won't get 7 hours (remember that C/20 rule I told you about?) - You'll probably get around 5. Of course, a 7Ah battery is nice and small - So then you look at a 16Ah battery - or better, a 20Ah - that sounds about right - it's not as good as c/20, - but it'll give you 8 hours, and with an all day recovery, might even give you most of a second night - of course, you can go bigger - I have a few 100Ah+ batteries sitting around, but they are the size of car batteries...
The numbers I gave assumed a 1 amp draw - if it's less, you can live with smaller batteries, if it's more, you need larger
ooooo... battery chemistry! hehehe
DO NOT be tempted by lithium polymer batteries if you come across them. They are VERY light weight and can deliver some pretty incredible numbers when it comes to capacity in relation to their size and weight, but that comes with a price. And it can be a steep price. Not so much in terms of money even though they are still a bit pricey, but in terms of safety.
I fly radio controlled airplanes. Keeping weight down is a priority. I have one plane that flies at all of about 7 ounces with 2 ducted fans. They are driven by a pair of Lithium polymer batteries in series. They are stored in an ammunition box, surrounded by cinder blocks and covered by a plastic bag full of dry sand. Why? Because they have been PROVEN and DOCUMENTED to burn violently if overcharged, charged to fast, or damaged in ways that you can't even see. I only charge them outdoors. People have lost cars and garages because of fire from them. I sure wouldn't want them in use near me when I'm sleeping.
DO NOT be tempted by lithium polymer batteries if you come across them. They are VERY light weight and can deliver some pretty incredible numbers when it comes to capacity in relation to their size and weight, but that comes with a price. And it can be a steep price. Not so much in terms of money even though they are still a bit pricey, but in terms of safety.
I fly radio controlled airplanes. Keeping weight down is a priority. I have one plane that flies at all of about 7 ounces with 2 ducted fans. They are driven by a pair of Lithium polymer batteries in series. They are stored in an ammunition box, surrounded by cinder blocks and covered by a plastic bag full of dry sand. Why? Because they have been PROVEN and DOCUMENTED to burn violently if overcharged, charged to fast, or damaged in ways that you can't even see. I only charge them outdoors. People have lost cars and garages because of fire from them. I sure wouldn't want them in use near me when I'm sleeping.
_________________
| Mask: Swift™ FX Nasal Pillow CPAP Mask with Headgear |
| Humidifier: S9™ Series H5i™ Heated Humidifier with Climate Control |
| Additional Comments: original pressure 8cm - auto 8-12 |
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ProfessorSleep
- Posts: 338
- Joined: Sat Sep 10, 2005 7:42 pm
- Location: Wisconsin
Yardbird, it's the little things like that - explosion, fire, major property damage, devastation, and bodily mutilation that lead me to make this more complicated than it needs to be! It's so simple on the surface-- buy a battery and charger/hook it up. Easy enough. Except for the risks above. Even the "regular" batteries can be quite dangerous. Tending to value safety very highly, thanks for the warning!
ProfessorSleep-
What's probably even funnier about those Lithium Polymers is that each pair is about the size of a large book of matches. Or... like 2 tea bags. Made of a foil-like material. They're so small but have so much protection around them, it looks like you're storing a piece of plutonium or something. The bag of dry sand on top is just in case they burn and go through the ammo box, it'll pop the plastic bag and they'll get smothered in sand. Actually been tested and proven effective.
My gut feeling on a battery for CPAP use is the gel cell. They don't vent. Anything spillable or that vents is not something I want next to my bed. I'm seriously looking at converting a 5000 watt generator I already have over to liquid propane. A 4-stroke motor less than 12 horsepower can EASILY be run on propane. In fact you can run it on propane without changing the carburetor and then you can still run it on gasoline too if you want. I guess I'm just not all that concerned about power failures yet.
What's probably even funnier about those Lithium Polymers is that each pair is about the size of a large book of matches. Or... like 2 tea bags. Made of a foil-like material. They're so small but have so much protection around them, it looks like you're storing a piece of plutonium or something. The bag of dry sand on top is just in case they burn and go through the ammo box, it'll pop the plastic bag and they'll get smothered in sand. Actually been tested and proven effective.
My gut feeling on a battery for CPAP use is the gel cell. They don't vent. Anything spillable or that vents is not something I want next to my bed. I'm seriously looking at converting a 5000 watt generator I already have over to liquid propane. A 4-stroke motor less than 12 horsepower can EASILY be run on propane. In fact you can run it on propane without changing the carburetor and then you can still run it on gasoline too if you want. I guess I'm just not all that concerned about power failures yet.
_________________
| Mask: Swift™ FX Nasal Pillow CPAP Mask with Headgear |
| Humidifier: S9™ Series H5i™ Heated Humidifier with Climate Control |
| Additional Comments: original pressure 8cm - auto 8-12 |
Educated
I completly agree....this is actually what my theisis was based upon.biggziff wrote: You can power anything AC with them (other than big appliances).
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sleepless coot
- Posts: 2
- Joined: Sat Dec 10, 2005 9:26 pm
I have a UPS on my Remstar with heater. It is a 300 watt unit so it should run several minuets as it is advertised to run a 300 watt PC for four minuets. I have used it for a year. The UPS beeps when the power goes off so I hope it wakes me up. I am considering an alarm activated by a drop relay so when there is no power a battery powered alert makes a lot of noise.
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LJJ
How to control remstar heated humidifier
Derek or any other kind soul. I notice that you are using the remstar integrated heated humidifier. I understand that this needs to be not plugged into the CPAP machine during battery use. How then do you turn it on if it is not plugged into the remstar CPAP machine? I see no other control but on the machine itself. Thanks.
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GoodKnight
- Posts: 65
- Joined: Fri Jul 29, 2005 9:21 am
- Location: California
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LJJ
We lost power last night. I have my Remstar Auto (CFlex) w/ heated humidifier plugged into an APC UPS that was designed for computers.
This discussion brings up some very important points.
My integrated heated humidifier is connected to the CPAP through a cable in the back. This means that there is only ONE plug for the 120v outlet. Since I plug that one plug into the UPS, I am also hooking the humidifier up to it.
Last night, the power went off just before I went to bed so I did not have the CPAP turned on yet. If I had already been sleeping (by the way I run my heater at 2), the humidifier would automatically start draining the battery and, as discussed above, could potentially burn up.
The UPS has a very loud beeping alarm that starts as soon as power is cut. I guess I could wake up and turn the heater off and let the CPAP run but there is another problem... I ran just the CPAP on the UPS last night and it only went for about 20 minutes before the UPS started beeping constantly - as if to warn me that battery failure was imminent. Give me a break! I ended up sleeping without it until just after 1AM when the power came back on.
I do have a DC cord for use when camping (in my travel trailer) - but only need it if the campground has no AC power.
I can not stand to be without my CPAP at night but am confused about which of the above mentioned options would be best for me. I don't mind running without the heated part, but a can NOT be without the CPAP.
Does anyone else have the same machine (Remstar Auto with CFlex) and know what the current draw is withOUT the heated humidifier running? I need to come up with something better so I don't lose any more sleep.
Thanks!
Vince
This discussion brings up some very important points.
My integrated heated humidifier is connected to the CPAP through a cable in the back. This means that there is only ONE plug for the 120v outlet. Since I plug that one plug into the UPS, I am also hooking the humidifier up to it.
Last night, the power went off just before I went to bed so I did not have the CPAP turned on yet. If I had already been sleeping (by the way I run my heater at 2), the humidifier would automatically start draining the battery and, as discussed above, could potentially burn up.
The UPS has a very loud beeping alarm that starts as soon as power is cut. I guess I could wake up and turn the heater off and let the CPAP run but there is another problem... I ran just the CPAP on the UPS last night and it only went for about 20 minutes before the UPS started beeping constantly - as if to warn me that battery failure was imminent. Give me a break! I ended up sleeping without it until just after 1AM when the power came back on.
I do have a DC cord for use when camping (in my travel trailer) - but only need it if the campground has no AC power.
I can not stand to be without my CPAP at night but am confused about which of the above mentioned options would be best for me. I don't mind running without the heated part, but a can NOT be without the CPAP.
Does anyone else have the same machine (Remstar Auto with CFlex) and know what the current draw is withOUT the heated humidifier running? I need to come up with something better so I don't lose any more sleep.
Thanks!
Vince
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Guest
Power outages are common in my area......just in the last month we had three, all of them during the night. And they last.....anywhere from a few hours to several days. Got a little paranoid about going to sleep.....Oh2Breathe......have you been watching those Canadian Tire sales? The Eliminator Powerbox 1200 was recently on sale for 199.99 (CDN). One of these monsters now awaits my next power failure. Comes with 5A charger, and cig-lighter cord for charging from vehicle. Can also be charged by solar panel. This unit will give me a few nights sleep before I have to worry about recharging. Also have Resperonics cpap/cig-lighter cable for DC.
Hey Idzeeboo.....
A Remstar auto w/cflex and no humidifier draws a fairly steady 1.5 amp DC (@12 VDC) with the unit set for auto and the pressure set for 8.5 - 10 cmH2O.
A 12 volt sealed lead acid battery rated around 20 amp-hours should get you one night's therapy without messing up the battery. And the battery size at that rating is reasonable, not too heavy, and not too expensive.
As is shown in this thread, the computer UPS systems don't last very long, and are only reasonable solutions when you believe power outages will be very short duration.
Good luck!
A 12 volt sealed lead acid battery rated around 20 amp-hours should get you one night's therapy without messing up the battery. And the battery size at that rating is reasonable, not too heavy, and not too expensive.
As is shown in this thread, the computer UPS systems don't last very long, and are only reasonable solutions when you believe power outages will be very short duration.
Good luck!