Resmed AIRMINI and Battery

shb wrote: ↑

Thu Apr 26, 2018 7:17 pm

I think that the only thing I need to do is a get a cable made to take the OUT socket from the S9-DC-converter and be able to plug into the Airmini.. Here are the connectors..

QUESTION --- Can anyone see why this will or will not work after I get the cable made ? OR can anyone see an easier way to use my C266 with the airmini ???

Those look like connectors specifically manufactured for ResMed. Although there may be third party equipment for s9 power I expect ResMed is likely currently the only source for the AirMini connector.

I dont think the connectors are exclusively for RESMED and for RESMED only....

The proof is here : https://buyminicpap.com/products/batter ... or-airmini

They are 3rd party.. They are not RESMED.. They have the connector on their cable. Case closed.

shb wrote: ↑

Fri Apr 27, 2018 3:29 am

I dont think the connectors are exclusively for RESMED and for RESMED only....

The proof is here : https://buyminicpap.com/products/batter ... or-airmini

They are 3rd party.. They are not RESMED.. They have the connector on their cable. Case closed.

Perhaps a replacement cable for their battery would be a good starting point then. It looks like it has a more standard barrel connector on the other end.

The proprietary nature of ResMed power would.be a HUGE DEAL BREAKER , especially
when shopping for a travel machine. Somebody shot themselves in the foot.

chunkyfrog wrote: ↑

Fri Apr 27, 2018 4:39 am

The proprietary nature of ResMed power would.be a HUGE DEAL BREAKER , especially
when shopping for a travel machine. Somebody shot themselves in the foot.

Two somebodies, Resmed as usual, and the buyer who didn't do their homework. Then there is the Battery owner that bought a non standard battery that couldn't put out a standard 12 volt range. Jim

I would think a "Travel Machine's", top plan would be to make travel easy.... Not So.

"Somebody" is inclusive enough, which explains my choice of words.
The tiny machines appeal to one's vanity; but vanity has its place . . .
And its tradeoffs. Not everyone chooses wisely.

Keep in mind this is a lithium ion battery pack. It is made up of 3 cells in series. The 11.1 volts is the voltage at mid discharge. Fully charged is 4.2 volts per cell which would give you 12.6 volts and that should work fine with your set up. Low voltage cut off is somewhere around 3 volts per cell or 9 volts for the battery and that may be too low for some applications.

If you look at a discharge graph of a lithium ion cell the mid point voltage is around 3.7 volts and that is where the 11.1 volts comes from. In other words you start at 12.6 volts and by the time you have used half of the capacity you are at 11.1 volts.

Now if the battery is worn out the voltage will drop as soon as a load is put on it.

A good way to check the battery is to fully charge it, let it sit overnight, then measure the open circuit voltage. It should be close to 12.6 volts. If it is 12 volts or less the battery is pretty much worn out and should be scheduled for replacement.

Goofproof wrote: ↑

Fri Apr 27, 2018 10:46 am

Resmed as usual, and the buyer who didn't do their homework. Then there is the Battery owner that bought a non standard battery that couldn't put out a standard 12 volt range. Jim

In this case - I already had the battery for a couple of years. And it works perfectly with the Resmed S9. It is marketed as a 12v battery specifically for CPAP. In fact if you read the specs of the S9 and you read the specs of the Airmini - everything actually points to the battery working with both... HOWEVER - what is different -- but not descirbed in the specs is this --- The RESMED s9 DC adapter IS TOLERANT OF the output voltage of the battery being slightly under 12v ( in this case 11.1) , whereas the RESMED airmini DC adapter IS NOT TOLERANT OF the battery being slightly under 12v ouput..

That is the only difference, And PLEASE, I defy you, or anyone, to show where that detail is specifically written, or even alluded to, in any specs or documentation about the AirMini or the Airmini DC adpater... Go Ahead... It is not there.

The fact is - this scenario shows precisely the type of information that is not in the documentation , and illustrates why forums like cpaptalk.com are so valuable ! This forum provides real life "extra information" that is not contained anywhere else.

HoseCrusher wrote: ↑

Fri Apr 27, 2018 1:03 pm

Keep in mind this is a lithium ion battery pack. It is made up of 3 cells in series. The 11.1 volts is the voltage at mid discharge. Fully charged is 4.2 volts per cell which would give you 12.6 volts and that should work fine with your set up. Low voltage cut off is somewhere around 3 volts per cell or 9 volts for the battery and that may be too low for some applications.

If you look at a discharge graph of a lithium ion cell the mid point voltage is around 3.7 volts and that is where the 11.1 volts comes from. In other words you start at 12.6 volts and by the time you have used half of the capacity you are at 11.1 volts.

Now if the battery is worn out the voltage will drop as soon as a load is put on it.

A good way to check the battery is to fully charge it, let it sit overnight, then measure the open circuit voltage. It should be close to 12.6 volts. If it is 12 volts or less the battery is pretty much worn out and should be scheduled for replacement.

Thaanks for that information !! I will try it with the c266 fully charged in a few days.. Even if that works, it is not great as it means that the airmini ( using the airmini dc adpater ) will only run for the first half of the fully charged battery, whereas the s9 dc adapter is happy to run for the whole battery.. The difference could be 3 nights of operation versus 6-7 nights of operation. My preferred solution is still to make a cable that will allow me to run the airmini using the s9 dc adapter so I get the best of both worlds.

How could your battery be made to specs for a product two years before it's marketed. Does not Compute! Also after two years it probably will not meet new specs. I have gotten a battery that was closer to 14 volts, so it would have had wiggle room. Jim

Also voltage needs to be checked under load, without load voltage means nothing except pressure (Voltage) in there. It's flow (Amps) that do the work....

Goofproof wrote: ↑

Fri Apr 27, 2018 10:46 am

I would think a "Travel Machine's", top plan would be to make travel easy.... Not So.

The battery aside - I have used the Airmini in planes ( QANTAS from US to Australia happily provided me a seat with power socket - row 44 ). And it performed great.

I travel alot with business. I have always taken the s9 or s8 with me. With the airmini there are 2 main problems that I see. First is thhis -- there is no way to get data. It provides completely inadequate summary data. It has an "AVERAGE Events per hour" ( but not broken into AI and AHI )... and not the MAXIMUM... It shows one single figure for pressure - which is NOT the maximun and NOT the average... and there is no way to get a timeline with any further information.. or information on a timeline ... or anything that can be loaded into sleepyhead.



Next is the airflow it seems not quite as good as the S9 -- at SAME PRESSURE -- it seems to deliver LOWER litres per minute ?? But I cannot find those specs for the S9 -- anyone ?

Here are the flow numbers for the Airmini

I found it -- here is the S9 flow numbers ... Comapre to Airmini above



At 8cm H20 pressure -- I am getting way less air flow per minute than the S9 . And I really notice it..

The airmini is easier to travel with. But the S9 is much better.

Goofproof wrote: ↑

Fri Apr 27, 2018 10:02 pm

How could your battery be made to specs for a product two years before it's marketed. Does not Compute! Also after two years it probably will not meet new specs. I have gotten a battery that was closer to 14 volts, so it would have had wiggle room. Jim

Also voltage needs to be checked under load, without load voltage means nothing except pressure (Voltage) in there. It's flow (Amps) that do the work....

Jim - you need to read the posts more closely.

Repeat - I been using this battery successfully without issue - on the Resmed S9 - since I bought the battery. The issue here *is not the battery * .. The issue is the Resmed Airmini DC adapter.

The battery can happily power the unit . Basic physics , power is volts x amps ( there's plenty of power). The problem is the airmini dc adapter cuts out ( even when the airmini is NOT connected ) .

This battery can happily drive the airmini...

Look above - I show a picture of it driving the airmini ( using a $30 inverter) . The problem is the Airmini-DC-converter-- which does not play. It is nothing about "under load" or "not under load" .. The airmini DC converter does the same thing - even when nothing is connected to it... Just the airmini dc converter connected to the battery.

shb wrote: ↑

Fri Apr 27, 2018 10:36 pm

I found it -- here is the S9 flow numbers ... Comapre to Airmini above



At 8cm H20 pressure -- I am getting way less air flow per minute than the S9 . And I really notice it..

It's all in your imagination.

Those are the maximum leaks that the machine can maintain pressure at, which, unless you've got a truly terrible mask seal, is totally irrelevant.

If you look in the back of your mask manual, you'll see what the airflow is out the vent at 8cm pressure. it's far less than either machine's max. (maybe 30lpm)