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[Equipment] ResMed Airsense 11 battery backup
#61
RE: ResMed Airsense 11 battery backup
I was unable to get the airmini dc to dc adapter to work with the airsense 11 using a 12v deep cycle battery. Took a chance and bought it, but no go.
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#62
RE: ResMed Airsense 11 battery backup
(04-26-2022, 10:59 PM)davidgr Wrote: I was unable to get the airmini dc to dc adapter to work with the airsense 11 using a 12v deep cycle battery. Took a chance and bought it, but no go.

That’s odd. I’ve been using one every night for five months now with my Airsense11. Works great, and I’ve slept through several long power outages with it over the winter. 

Is your battery fully charged?  Maybe you got a defective converter?
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#63
RE: ResMed Airsense 11 battery backup
(04-27-2022, 09:06 AM)ScottZZZ Wrote: That’s odd. I’ve been using one every night for five months now with my Airsense11. Works great, and I’ve slept through several long power outages with it over the winter. 

Is your battery fully charged?  Maybe you got a defective converter?

My theory now is that my deep cycle battery is old and I did not use or maintain it properly. I didn't know whether I should have kept it trickle charged over the past year since my last camping trip, or what. But the battery is several years old now and has just been used a few times over the years and I didn't keep it charged in between. So I will buy a new one and retry the experiment. I'll bet that that solves it. Thanks for your response. Any comments on deep cycle battery care?
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#64
RE: ResMed Airsense 11 battery backup
Sounds like battery condition is probably the problem then.  The AirMini DC-to-DC converter is a "boost" converter, increasing the input voltage to the 24V needed by the Airsense.  It has a pretty strict minimum input voltage, under load, of 11.4V.   If the battery drops below 11.4V during use, the converter will shut down.  

Battery maintenance depends a little on the exact type of battery (flooded, gel, deep-cycle, etc.) but as a "general rule"...   Lead acid batteries all slowly "self-discharge" when idle so they should have a "trickle charge" applied to maintain them during storage. Ideally, they should not spend much (if any) time below about 2.05V per cell (so 12.3V no-load for a standard 6-cell 12V battery).  Storing them below that will shorten their life.  They can safely go below that, down to perhaps 11.4V when under load, but the AirMini DC-to-DC converter cuts off below 12.4V so that won't happen during use.

The "smart" battery chargers or "maintainers" keep a small charging current on the battery once fully charged, maintaining it at about 2.25 volts per cell (so about 13.5V total).  That ensures it is always fully charged, ready for use.  This is all that's needed for "storage" between uses.
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#65
RE: ResMed Airsense 11 battery backup
(04-27-2022, 04:45 PM)HScottZZZ Wrote: Sounds like battery condition is probably the problem then.  The AirMini DC-to-DC converter is a "boost" converter, increasing the input voltage to the 24V needed by the Airsense.  It has a pretty strict minimum input voltage, under load, of 11.4V.   If the battery drops below 11.4V during use, the converter will shut down.  

Battery maintenance depends a little on the exact type of battery (flooded, gel, deep-cycle, etc.) but as a "general rule"...   Lead acid batteries all slowly "self-discharge" when idle so they should have a "trickle charge" applied to maintain them during storage. Ideally, they should not spend much (if any) time below about 2.05V per cell (so 12.3V no-load for a standard 6-cell 12V battery).  Storing them below that will shorten their life.  They can safely go below that, down to perhaps 11.4V when under load, but the AirMini DC-to-DC converter cuts off below 12.4V so that won't happen during use.

The "smart" battery chargers or "maintainers" keep a small charging current on the battery once fully charged, maintaining it at about 2.25 volts per cell (so about 13.5V total).  That ensures it is always fully charged, ready for use.  This is all that's needed for "storage" between uses.

So to clarify, (three questions) 1) I can leave the charger / maintainer connected to the battery continuously between one summer and the next, and that should keep it alive and well.? 2) Any way to revive the old battery, or is that not really possible any longer? Lastly, 3) I'm not knowledgeable about watts and volts and all. Here's the charger that I use - Black and Decker BC2WBD (google it) - Is this a decent choice of chargers? thanks again Scott.
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#66
RE: ResMed Airsense 11 battery backup
1 - Yes, between uses the easiest way to keep the battery healthy is keep it connected 24x7 to a charger designed to provide a low-amperage "trickle" charge. You could also check the battery's state of charge periodically and charge when needed (i.e., when it falls below about 14.5V), but as long as the charger is designed for maintenance it is easier (and safe) to just keep it connected all the time.

2 - Probably not. There are "smart" chargers that claim the ability to de-sulfate the plates through various higher-than-normal voltage burst techniques, but results are mixed at best. A "lightly" damaged battery might (or might not) be improved via such techniques, but generally the damage is permanent.

3 - Based on the manufacturer's description, and the bulk of the reviews, I'd say that charger would be fine. At 2A maximum, it isn't going to charge very fast -- so if you bring home a depleted 70Ah battery, it could take 3+ days to recharge. As long as that recharge time is acceptable, it should be fine.

It sounds like your usage is for periodic, off-grid use when camping. For that, you need to charge/maintain the battery between uses, and then take the battery on-site and use it to power your CPAP. That should be fine with the charger you have, as long as you have a few days between uses.

For people who want to have the battery connected to a charger AND their CPAP continuously, to act as a "UPS" when power goes out... It's probably best to have a charging source capable of 5-6 Amps because that's what the Airsense 11 (with humidifier) can draw. Having a charge current less than that would mean that when the AirSense was running, it would be depleting the battery because the charger amperage is less than the load. That would mean a partial discharge/recharge of the battery every single night, which would be considerable wear on the battery.

For continuous "UPS-like" operation, this is the charger and battery I use:
- https://www.chromebattery.com/12v-55ah-s...inals.html
- https://samlexamerica.com/products/23-am...p-circuit/

That power supply / charger there is a relatively expensive solution, but I've been using it for 8+ years, 24x7. I'd be hesitant to recommend it due to the cost, but for an "uninterruptable power WITH long run-time" it has been a great solution. It is purpose-made to provide enough amperage (when AC is present) to run the CPAP+Humidifier without any battery drain, keep the battery at a constant charge, and instantly transfer the load to the battery when the AC is lost.
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#67
RE: ResMed Airsense 11 battery backup
(04-27-2022, 06:59 PM)ScottZZZ Wrote: 1 - Yes, between uses the easiest way to keep the battery healthy is keep it connected 24x7 to a charger designed to provide a low-amperage "trickle" charge. You could also check the battery's state of charge periodically and charge when needed (i.e., when it falls below about 14.5V), but as long as the charger is designed for maintenance it is easier (and safe) to just keep it connected all the time.

2 - Probably not.  There are "smart" chargers that claim the ability to de-sulfate the plates through various higher-than-normal voltage burst techniques, but results are mixed at best.  A "lightly" damaged battery might (or might not) be improved via such techniques, but generally the damage is permanent.

3 - Based on the manufacturer's description, and the bulk of the reviews, I'd say that charger would be fine. At 2A maximum, it isn't going to charge very fast -- so if you bring home a depleted 70Ah battery, it could take 3+ days to recharge.  As long as that recharge time is acceptable, it should be fine.

It sounds like your usage is for periodic, off-grid use when camping.  For that, you need to charge/maintain the battery between uses, and then take the battery on-site and use it to power your CPAP.  That should be fine with the charger you have, as long as you have a few days between uses.

For people who want to have the battery connected to a charger AND their CPAP continuously, to act as a "UPS" when power goes out...  It's probably best to have a charging source capable of 5-6 Amps because that's what the Airsense 11 (with humidifier) can draw.  Having a charge current less than that would mean that when the AirSense was running, it would be depleting the battery because the charger amperage is less than the load.  That would mean a partial discharge/recharge of the battery every single night, which would be considerable wear on the battery.

That power supply / charger there is a relatively expensive solution, but I've been using it for 8+ years, 24x7.  I'd be hesitant to recommend it due to the cost, but for an "uninterruptable power WITH long run-time" it has been a great solution.  It is purpose-made to provide enough amperage (when AC is present) to run the CPAP+Humidifier without any battery drain, keep the battery at a constant charge, and instantly transfer the load to the battery when the AC is lost.
Great answer. FYI while we're talking. I'm in Vancouver, WA. Which part of the world are you in?

Your samlex gadget looks interesting. I figure that if I kept the deep cycle battery charged at home, a power outage would wake me and I would grab the battery and hook it up. But outages are really infrequent anyway.

Let's talk amp hours. Your battery is 55 Ah. How many amps does the airsense 11 draw without the humidifier; which I usually don't use in the summer? How many airsense 11 hours can you get from a fully charged 55 Ah battery? I am going camping for 5 nights in early June in the CA Redwoods (Yay!!). Maybe a 100 Ah deep cycle battery is worth considering? I also end up with needing to figure out how to recharge the battery. Sometimes you can run a cable from the restroom, and sit and babysit your battery while it charges; an argument for a larger amperage charger I assume. I wonder how much charge I would get in an hour with the 2A charger I have. A whole night? Still that's an hour a day that I have to sit around.

There's the topic of lithium batteries. I see that Jackery and Rockpals have expensive portable units on amazon. As lithium batteries improve and become cheaper, they would be worth considering. I wish solid state batteries were further along. I wonder if something like the Rockpals and Jackery might eventually be worth it. On vacation you usually do some driving each day, and that kind of battery I think can be charged by your cigarette lighter while you are driving around. But not sure if those kinds of units are worth it at this point.
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#68
RE: ResMed Airsense 11 battery backup
In the tests I did with a 12V battery and the AirMini DC-to-DC converter, I saw anywhere from 1.5-2.5A for just the blower.  The heated hose and humidifier add another 2.0-2.3A (so 3.5-4.8A total).  These numbers vary based on pressure and humidity setting, and they aren't constant -- the current increases/decreases as the blower is loaded/unloaded with each breath, and as the humidifier cycles on/off.  Bottom line, different people with different settings and different ambient temperature/humidity will see different results.

In theory, a 55AH battery with 5A load would provide 11 hours.  But in practice, it is generally less for several reasons including lowered capacity with battery age, and difference in the real-world load and cutoff voltage versus the load and cutoff voltage the manufacturer uses in battery testing / marketing.  

All that said...  I can get about 10+ hours from my two-year old 55AH battery and the Resmed AirMini DC-to-DC converter, WITH my normal pressure, humidity, and heated hose all running. Without the humidifier and heated hose, it's more like 25-30 hours.  

Charging time will also depend on battery condition and temperature as well as the charger current.  In a perfect world, that 2A charger would add about 2AH of capacity to the battery every hour.  If your AS11 (without humidifier/heated tube) uses 1.8-2.0A, then you will need about as many hours to recharge as the hours you slept.   You can speed that up with a 6A or 10A charger -- which will charge 3x or 5x as fast as the 2A charger (again, in a perfect world -- so these are estimates).  I personally wouldn't go over 10-12A for a typical 55-75AH battery.  In theory, you can safely go higher but higher charge rates can also reduce battery life.  In any case, be sure to get a "smart" charger as they will sense the battery's state-of-charge and reduce voltage/current as the battery approaches full charge to avoid overheating or overcharging.  

You are also correct about the lithium batteries and power units.  They are WAY lighter and more compact for similar capacity, but also quite a bit more expensive.  Hopefully as the technology improves and production increases, the cost will continue to decrease.
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#69
RE: ResMed Airsense 11 battery backup
(04-25-2022, 09:04 PM)332EMDG Wrote: All,

Hello.  Newbie here.  Thanks to some guidance from mod SuperSleeper, I just wanted to share with all that I think I found a DME that is shipping the Freedom V2 battery with the ResMed AirSense 11 adapter cable.  If I understand the rules correctly, I am allowed to simply say the name of the company, which is "RA Supply Corporation".    

Once you find them, you will know that you are in the right spot because they have a blue circle with a battery symbol on the top of the page.  They specialize in medical batteries according to their FAQ's.  I ordered from them yesterday, and they have my battery with ResMed AirSense adapter cable on the way! 

I am only trying to help share this great news as I myself was recently issued the 11 and dumbfounded without being able to find a place from the more popular suppliers.

Hope this helps.

Cheers.

V/r

Todd

Follow up to my previous post. If anyone wants close-up photos, please DM me and I can email them.

The Freedom V2 Battery arrived, factory sealed with the ResMed AirSense 11 kit.  The kit number is SV2-A11, which does not appear on the manufacturer's own website.  I reckon it's only a matter of time before all the other major CPAP suppliers that already sell the Freedom V2 will start to sell this. I can now sleep again with confidence when and if the power goes out.  I hope this helps.

Cheers.

V/r

Todd
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#70
RE: ResMed Airsense 11 battery backup
Hi Scott. David here. I have an update. Looks like the deep cycle battery was not dead after all. I let my charger charge my deep cycle battery for a couple of days; and the battery fully-charged light on the charger was on. I decided to do a test and found that it did still run my old philips dreamstation.

But when I plug in the airsense 11 with the airmini adapter, it still does not work. What happens is that when I initially attach the deep cycle battery to the airmini adapter, the green light on the airmini adapter is on. So far so good. But when I plug that into the airsense 11, the green light on the adapter goes out and there is no power on the airsense 11. What do you think might explain that?

One more test. My car battery. Wow. It worked in the car cigarette lighter AND also directly attached to my battery with the hood open. So the problem IS the deep cycle battery I'm using. Weird that the old cpap works, but the new one does not. The battery is an Everstart 24dc. Nope. The dc is not volts. It is battery size. It is 101 amp hours. So a bit of a mystery still, but at least I know that airmini adapter works and that mine is not a dud. So I will buy a new deep cycle battery, if I don't end up springing for that tempting lithium battery. I wonder if a deep cycle battery can get me through 5 nights of 8 hours sleep with the humidifier and hose heater off? 40 hours. Possible? Those agm deep cycle batteries look interesting.

Scott's thoughts?
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