Backup power options for CPAP machines

[OMyMyOHellYes]

Yeah - don't worry about a 24 V system for the REsmed machines. It would only really make sense if you could power your machine directly from the battery. As the folks at Resmed designed it, their machines will only work off of their power supplies or their 12-24 V converters. 'tis one reason why I chose the PR SystemONE .... It works fine straight off a battery.

OMMOHY

[Sn00zeAlarm]

One other note: the ResMed A10 draws 8 watts even when "off" so be sure to unplug it when not in use, if you are on battery power.

My batteries are already 24v - the extra work would be in making a proper power cord to fit the connector on the back of the machine, just to save about 1 watt.  Not worth it with the 1,000 Watt-Hour capacity I have to work with.

[OMyMyOHellYes]

Thanks to the evil geniuses at ResMed, making your won cord to run their machines off of 24 V batteries is WAY more work than it is worth. Did you bother to read the many page document on the topic? Where list members reverse engineered the evil design that ResMed put in place?

OMMOHY

[mckevin32]

For the cost, I could get ten 35 Ah AGM batteries.  Yes they are heavier, but every bit as capable and I would get 350 AH as opposed to approx 33 Ah capacity from ONE of these.  

In the case of ten 35 Ah batteries, that's almost 80 days of CPAP use without ever thinking of charging.

Then again, I do quite nicely on my homebrew CPAP UPS that consists of a 35 Ah battery, a powergate/charger (West Mountain specifically-the Astrons powergates don't have true smart charging capability) and a commercial power supply.  If power fails while using heated humidification, no problem.  Automatic switchover to big battery if power mains drop, returns to mains as soon as they come back online and automatically recharges/maintains the battery.  User never knows power dropped caus they sleep through it.  I have 3-4 full nights capacity without doing anything.  Of course, as soon as I realize power is off, I would shut off humidification and that would get me probably 5 more nights on that battery.  Then switch to another spare for 8 nights.  All rigged with Anderson PowerPoles for easy, rapid hookup.

OMMOHY

If I may resurrect this...

I think this is exactly what I've been looking for!  Can you poke holes in this?
Looking for a power failure solution for 2 Dreamstations (wife and I).  Strictly for power outages, typically lasting a few hours, don't give a hoot about portability.

The PWRGATE PG40S mounted on a Minn Kota Trolling Motor power center (batt box with 2 12v cig lighter outputs).  Power supply to the PS input, deep cycle battery to the BATT, and the output to the cig lighter plugs on top of the box, where the 12v power cables to the Dreamstations take off.

Any clue what I might need for a power supply?

Thanks!!
mckevin

[Ockrocket]

For the cost, I could get ten 35 Ah AGM batteries.  Yes they are heavier, but every bit as capable and I would get 350 AH as opposed to approx 33 Ah capacity from ONE of these.  

In the case of ten 35 Ah batteries, that's almost 80 days of CPAP use without ever thinking of charging.

Then again, I do quite nicely on my homebrew CPAP UPS that consists of a 35 Ah battery, a powergate/charger (West Mountain specifically-the Astrons powergates don't have true smart charging capability) and a commercial power supply.  If power fails while using heated humidification, no problem.  Automatic switchover to big battery if power mains drop, returns to mains as soon as they come back online and automatically recharges/maintains the battery.  User never knows power dropped caus they sleep through it.  I have 3-4 full nights capacity without doing anything.  Of course, as soon as I realize power is off, I would shut off humidification and that would get me probably 5 more nights on that battery.  Then switch to another spare for 8 nights.  All rigged with Anderson PowerPoles for easy, rapid hookup.

OMMOHY

If I may resurrect this...

I think this is exactly what I've been looking for!  Can you poke holes in this?
Looking for a power failure solution for 2 Dreamstations (wife and I).  Strictly for power outages, typically lasting a few hours, don't give a hoot about portability.

The PWRGATE PG40S mounted on a Minn Kota Trolling Motor power center (batt box with 2 12v cig lighter outputs).  Power supply to the PS input, deep cycle battery to the BATT, and the output to the cig lighter plugs on top of the box, where the 12v power cables to the Dreamstations take off.

Any clue what I might need for a power supply?

Thanks!!
mckevin

The Dreamstation can run directly off 12 volt input..
I purchased a 12V power cord for it from a CPAP supplier here in Australia for $50 Au.

Then I got a socket and other bits to make up what I needed to attach to a 12 volt battery (there is a post on here somewhere about it, with pics from memory) that is not much larger than a motorcycle battery. 

My setup is primarily for when I go camping on my motorcycles, the battery can be recharged whilst riding my bike, and I can get about 15 hours total use from the battery between recharges.. so I can get 3 nights of 5 hours use if I'm just taying put in one campsite.

The battery can also be recharged from any mains outlet vehicle battery charger, so it can double as a backup unit for power outages when I'm at home as well.

For camping I can run without humidifier and heated hose, which would give me a bit more battery life than the 15 hours I can get with heat and humidity. 

I can also run it off any other 12 volt vehicle power outlet, or a battery jump starter pack such as I carry in my 4WD.

[mckevin32]

The Dreamstation can run directly off 12 volt input..
I purchased a 12V power cord for it from a CPAP supplier here in Australia for $50 Au.

Then I got a socket and other bits to make up what I needed to attach to a 12 volt battery (there is a post on here somewhere about it, with pics from memory) that is not much larger than a motorcycle battery. 

My setup is primarily for when I go camping on my motorcycles, the battery can be recharged whilst riding my bike, and I can get about 15 hours total use from the battery between recharges.. so I can get 3 nights of 5 hours use if I'm just taying put in one campsite.

The battery can also be recharged from any mains outlet vehicle battery charger, so it can double as a backup unit for power outages when I'm at home as well.

For camping I can run without humidifier and heated hose, which would give me a bit more battery life than the 15 hours I can get with heat and humidity. 

I can also run it off any other 12 volt vehicle power outlet, or a battery jump starter pack such as I carry in my 4WD.

That sounds perfect for camping and such but my goal is something I can leave hooked up 24/7, running off the power supply and auto switching to battery in the event of an outage (I REALLY hate the feeling of waking up gasping, trying to draw air through a dead hose). 

Of course there are easier ways to do it.  This, if I am understanding correctly, has the multiple advantages of being completely automatic, only switching to battery power when needed (while float charging the battery) so preserving battery life, and avoiding all of the AC/DC conversion nonsense.

[OMyMyOHellYes]

Sounds basically like what I propose and use (with some tweaks as I rework the wiring to use PowerPoles and ditch the cigar plugs and use no battery box). Waiting on mailman to bring a Super PWRgate to fix up the exact same system for my ham radios.

Look for a 12 V ham radio power supply - mine is 12 A. If you are running two units off of that with heat & humidification, maybe a 20 A 12 V would be better. Too much amperage capacity is OK; too little is not. Some spots to googleate and explore might include Ham Radio Outlet, DX Engineering, Cheapham, Gigaparts. West Mountain/Powerwerx offers a little 30 A power supply that would be OK, if not just a little overkill - that won't hurt anything though. As for brand/model reviews, check eham if you want some idea as to reputation ...

Switching power supplies are perfectly fine (cheaper and lighter) - you don't need a linear power supply. IIRC, you will need to adjust the output to approx. 14.1 V if you are keeping AGM batteries (read the instructions from West Mountain - it tells you -if you don't have one already, you can get an affordable digital multimeter to help tune the power supply output and they always just come in handy anyway.) Your machine should be perfectly fine will be perfectly fine with that, particularly if you are going through a ResMed converter. (or, like me, not - the PR SystemOne has never complained (note that your car's charging system would normally run 14+ V and its battery between 12.5 and 13.5V ))

Oh, one important thing, make sure there is an appropriately sized fuse in the circuit coming off the positive battery terminal... For a two machine system I would expect 10-15A to be more than enough.

[mckevin32]

Perfect.  Been trying to work through this with vanilla UPS units and just never seemed right, so when I saw your post it was a real light bulb moment! 
I finally thought to check the brick and it shows 6+ A. DC output, so I'm thinking a 20 A. supply should leave some breathing room.
Thanks for the links, that should be enough to get me there!

[HL649]

Take a look at these.  Commercial Link Removed, Instead search goal zero for power packs.

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[Ockrocket]

The Dreamstation can run directly off 12 volt input..
I purchased a 12V power cord for it from a CPAP supplier here in Australia for $50 Au.

Then I got a socket and other bits to make up what I needed to attach to a 12 volt battery (there is a post on here somewhere about it, with pics from memory) that is not much larger than a motorcycle battery. 

My setup is primarily for when I go camping on my motorcycles, the battery can be recharged whilst riding my bike, and I can get about 15 hours total use from the battery between recharges.. so I can get 3 nights of 5 hours use if I'm just taying put in one campsite.

The battery can also be recharged from any mains outlet vehicle battery charger, so it can double as a backup unit for power outages when I'm at home as well.

For camping I can run without humidifier and heated hose, which would give me a bit more battery life than the 15 hours I can get with heat and humidity. 

I can also run it off any other 12 volt vehicle power outlet, or a battery jump starter pack such as I carry in my 4WD.

That sounds perfect for camping and such but my goal is something I can leave hooked up 24/7, running off the power supply and auto switching to battery in the event of an outage (I REALLY hate the feeling of waking up gasping, trying to draw air through a dead hose). 

Of course there are easier ways to do it.  This, if I am understanding correctly, has the multiple advantages of being completely automatic, only switching to battery power when needed (while float charging the battery) so preserving battery life, and avoiding all of the AC/DC conversion nonsense.

So just skip all the complications of technology and over priced commercial products... just hook the machine up permanently to the 12 volt battery, hook a trickle charger that will keep the battery topped up from the mains.

The Dreamstation is 12 volt to start with, it runs off a transformer that drops the mains power to the required 12 volts, so by running from a 12 volt battery you are actually supplying it with the correct current it runs on.

Leaving the battery on a mains power trickle charger will keep it charged up, and batteries on trickle charge have a longer life than batteries that are depleted and recharged.. you will get years of life from a battery. 

Another advantage is that if the mains power goes down there is no "switch over" lag where the pressure will drop and wake you up.

You should be able to set the whole thing up for $150 or less (that is in Australian money, depending what country you live in it may be cheaper) 
The genuine 12 volt DC cord for the machine cost me $50, the battery was about $80 (got discount because I buy my car and motorcycle batteries from the same place, and about $15 for the female socket and connecter terminals to wire the socket to the battery.. I also added an in line fuse just in case. 

And the bonus is that you can take it camping.