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Before you can discuss "battery backup" you end to define your requirements & expectations.
For my Resmed system, I am assembling, but have not tested, a system to be used for extended power outage situations in the country.
I bought the 12V cord from our sponsor I purchased a 100W solar panel set & 45AH AGM battery from Harbor Freight. I have not yet assembled & tested.

My calculations estimate about 4 hours of good sun to charge and 5 days capacity if I do not use the humidifier or heated hose.

A rechargeable that could hold enough juice for 24 hours of operation and be able to re-up using variable voltages.

mc

prodigyplace wrote:Before you can discuss "battery backup" you end to define your requirements & expectations.

This is exactly right. Too often I've struggled with design parameters of a project only to realize that I've not properly defined my objectives in the first place.

You need to decide:

- DC or AC, or both?
- Portable, seldom moved, or will it rarely be moved?
- If portable, then by what means and what is your design weight limit?
- How many nights does it need to last?
- Does it also need to run the humidifier, heated hose, etc?
- what pressure do you use?
- How much do you want to spend?
- Is there anything else you need to power off this battery system (e.g. cell phone charger, etc)?

prodigyplace wrote:Before you can discuss "battery backup" you end to define your requirements & expectations.
For my Resmed system, I am assembling, but have not tested, a system to be used for extended power outage situations in the country.
I bought the 12V cord from our sponsor I purchased a 100W solar panel set & 45AH AGM battery from Harbor Freight. I have not yet assembled & tested.

My calculations estimate about 4 hours of good sun to charge and 5 days capacity if I do not use the humidifier or heated hose.

Not even doing the math I know there is no way 4 hours of sun is charging a 45 AH battery. The down side to traditional Lead acid batteries besides weight is most you kill the life of battery by drawing down in power to much.

mrcrayola wrote:A rechargeable that could hold enough juice for 24 hours of operation and be able to re-up using variable voltages.

mc

Thank you! This is the type of info I was asking for.

USMCVet wrote: Not even doing the math I know there is no way 4 hours of sun is charging a 45 AH battery. The down side to traditional Lead acid batteries besides weight is most you kill the life of battery by drawing down in power to much.

Not for a 45 AH battery at 0% or 20% charged state it would not, but to replenish one night's CPAP usage (no heat or humidifier) it should be more that adequate. I've done it with a 27 Watt panel no problem.

amenite wrote:

USMCVet wrote: Not even doing the math I know there is no way 4 hours of sun is charging a 45 AH battery. The down side to traditional Lead acid batteries besides weight is most you kill the life of battery by drawing down in power to much.

Not for a 45 AH battery at 0% or 20% charged state it would not, but to replenish one night's CPAP usage (no heat or humidifier) it should be more that adequate. I've done it with a 27 Watt panel no problem.

The resperonics website says that without heated tube or humidification you can get 14 hours of run time at 10cm on 90 wh. So even only getting 50 watts from a 100 watt panel one night of use should only take an hour. I know that is over simplification but shows that poster is not talking about charging after only one night.

Woody wrote:You need to consider that the Dreamstation runs on a 24v dc supply not 12v dc. So just using
a 12v battery isn't going to work. Resperonics does make a small adapter to let you use a 12v
battery for about $ 90.

The Dreamstation runs on 12 Volts, as does all modern Respironics units. You're thinking of the ResMed units that run on 24 volts and require a special signal in the plug. Although its possible to hack a plug that works, most people are content to use the DC/DC converter from ResMed. There are a few battery packs that come with the special plug and circuitry, but most ResMed users should use the converter if they desire battery power.

USMCVet wrote:

prodigyplace wrote:Before you can discuss "battery backup" you end to define your requirements & expectations.
For my Resmed system, I am assembling, but have not tested, a system to be used for extended power outage situations in the country.
I bought the 12V cord from our sponsor I purchased a 100W solar panel set & 45AH AGM battery from Harbor Freight. I have not yet assembled & tested.

My calculations estimate about 4 hours of good sun to charge and 5 days capacity if I do not use the humidifier or heated hose.

Not even doing the math I know there is no way 4 hours of sun is charging a 45 AH battery. The down side to traditional Lead acid batteries besides weight is most you kill the life of battery by drawing down in power to much.

A 100 watt panel can deliver about 8 amps in good sun. The "rule of thumb" is that you can expect on average 3 to 4 hours a day, depending on location and season. (Google "average sun hours" to find charts and tables.) This assumes you have a good view - no trees, etc - and reasonable luck with the weather. Since even a mild overcast can cut the power in half, and clouds can cut it 90%, you need a backup plan or large batteries. Also, the battery has issues that must be considered, such as a low "acceptance rate" when it get more than 80% charged, and you don't want want to drain too low. I try to keep my batteries healthy through several hundred cycles over 6 years, so I tend to run between 50% and 85% daily.

A 100 watt panel, well positioned (facing south with no trees) could generate 25 to 30 amp-hours a day on average. In practice I would expect less, maybe a lot less in a country area with limited horizons. On my boat I have 350 Watts of panels. There are no trees, but as the boat is turning on a mooring, only some of the panels are powered at a time. I average around 60 Amp-hours a day, enough to power the fridge and pumps, etc while I'm away, but If I'm on board (using more power) during a cloudy period I have to run an engine to keep up.

My hunch is that the 100 watt panel with a 45 AH battery would work fairly well to keep a cpap running, if that was the only load. If you were trying to run many devices I don't think you could count on fully charging the battery every day.

CapnLoki wrote:

Woody wrote:You need to consider that the Dreamstation runs on a 24v dc supply not 12v dc. So just using
a 12v battery isn't going to work. Resperonics does make a small adapter to let you use a 12v
battery for about $ 90.

The Dreamstation runs on 12 Volts, as does all modern Respironics units. You're thinking of the ResMed units that run on 24 volts and require a special signal in the plug. Although its possible to hack a plug that works, most people are content to use the DC/DC converter from ResMed. There are a few battery packs that come with the special plug and circuitry, but most ResMed users should use the converter if they desire battery power.

Exactly and the cord isn't $90 either https://www.amazon.com/gp/aw/d/B01FT8QU ... MK7J&psc=1 .

mrcrayola wrote:A rechargeable that could hold enough juice for 24 hours of operation and be able to re-up using variable voltages.

What do you mean by "variable voltages"? Do you mean international voltages, or do you have some other special need?

Here is a what I'm thinking for components so for.
Battery:
http://www.batteryspace.com/lifepo4-pri ... d-dgr.aspx

A/C charger:
http://www.batteryspace.com/smartcharge ... 40vac.aspx

Solar Charger:
http://www.batteryspace.com/Charge-Cont ... r-LFP.aspx

Cell balancing:
http://www.batteryspace.com/Smart-LED-B ... rrent.aspx

Still plenty to figure out like how to package it. Maybe a a hard plastic case so CPAP itself can be inside for protection when being transported?

USMCVet wrote:Here is a what I'm thinking for components so for.
Battery:
http://www.batteryspace.com/lifepo4-pri ... d-dgr.aspx

A/C charger:
http://www.batteryspace.com/smartcharge ... 40vac.aspx

Solar Charger:
http://www.batteryspace.com/Charge-Cont ... r-LFP.aspx

Cell balancing:
http://www.batteryspace.com/Smart-LED-B ... rrent.aspx

Still plenty to figure out like how to package it. Maybe a a hard plastic case so CPAP itself can be inside for protection when being transported?

If you are carrying your XPAP in a case with batteries, feel free to buy a extra cpap or to, very poor idea.. Jim

Goofproof wrote:

USMCVet wrote:Here is a what I'm thinking for components so for.
Battery:
http://www.batteryspace.com/lifepo4-pri ... d-dgr.aspx

A/C charger:
http://www.batteryspace.com/smartcharge ... 40vac.aspx

Solar Charger:
http://www.batteryspace.com/Charge-Cont ... r-LFP.aspx

Cell balancing:
http://www.batteryspace.com/Smart-LED-B ... rrent.aspx

Still plenty to figure out like how to package it. Maybe a a hard plastic case so CPAP itself can be inside for protection when being transported?

If you are carrying your XPAP in a case with batteries, feel free to buy a extra cpap or to, very poor idea.. Jim

Care to elaborate? Battery would be secured to case with separate section for CPAP with foam for it to rest in.

Your back will love the strain, the machine will love the vibration and the fumes, just a poor idea in general. Jim