Resmed AIRMINI and Battery

[shb]

Hello all...

I been using the resmed products since 2005... S8, S9 and have recently bought the new Air Mini.. but am still trying to get it to work with my battery...

I have a C266 battery that has been awesome for both the S8 and S9. I use it with the genuine Resmed DC converter. On the S9 the c266 will easily give me 6+ nights ( I use it without humidifier).
The c266 battery has a cigarette lighter socket on it. The S9 DC adpater is "90W"

So, I plug my new Airmini into the Resmed 65W DC adapter, and plug that into the C266 battery.... and the light on the 65W DC adapater glows amber for 3 or 4 seconds with fades to black/nothing.
This indicates it is "not getting enough power" .... Then I run the S9 all night (3 times) and after that, the C266 still shows as more than half full of charge. My conclusion: the battery has plenty of charge.

Can anyone explain this ?? I really want to use my exising C266 battery with my new airmini. I already had to re-mortgage my house to buy the Airmini in the first place.




The 90W dc converter works - with a resmed S9.
The 65W dc converter does not work - with a resmed AirMini.

Can anyone explain why this is so ?? and/or how I can get the airmini to work with a C266 battery ?

And - for extra points - why did Resmed make the airmini dc converter "65W" anyway ?? when the wall a/c power unit for the AirMini is only "20W".

[rcobourn]

Have you tested the 65W DC converter using a vehicle 12V accessory plug? The only obvious explanation is that it is defective.

[shb]

why did Resmed make the airmini dc converter "65W" anyway ?? when the wall a/c power unit for the AirMini is only "20W".

Typical power consumption: 6.3W
Peak power consumption: 27W

This from here : https://www.resmed.com/au/dam/documents ... -LoRes.pdf

But ... I'd just like my battery to work

[shb]

Have you tested the 65W DC converter using a vehicle 12V accessory plug? The only obvious explanation is that it is defective.

You mean take it to the car, and plug it into the cigarette lighter ?

hmmm.... good idea. I will do that when I get home from work tonight.

If the DC converter is defective - then that would be a great outcome as it is easy to get a replacement on warranty.

[prodigyplace]

Have you tested the 65W DC converter using a vehicle 12V accessory plug? The only obvious explanation is that it is defective.

You mean take it to the car, and plug it into the cigarette lighter ?

hmmm.... good idea. I will do that when I get home from work tonight.

If the DC converter is defective - then that would be a great outcome as it is easy to get a replacement on warranty.

Test it with the Airmini. That is how I tested my dc converter before I had my battery setup complete.

[CapnLoki]

If the converter fails when plugged into a car battery then you have an answer. But if it works, it could mean the the startup power causes the battery voltage to dip below an "under voltage" level that causes the converter to shut down. In other words, you might have to take the error message at its literal meaning. The 266 may just be getting old, or the new converter might have a different trigger point from the others.

The ratings such as "90W" or "65W" only indicate a maximum capability, and not how much power they are expected to provide in normal use. The high rating on the airmini converter does seem odd - perhaps its designed for some future accessory like a real humidifier, or battery pack. Or maybe it was left over from some other product.

[shb]

I plugged the airmini's 65w dc converter into the socket in my car ( the airmini not attached ) -- and the indicator light glows green.

Then I plugged the same dc converter ( again no airmini attached ) into the c266 -- and the light glows amber for 4-5 seconds then goes off.

So - now I will go to sleep using the same c266 battery powering my old resmed s9 for the 4th night without recharging... Doesn't that show that the battery is pushing out enough power for it to work ???? To me it looks like the converter is over engineered to the point that it prevents what is actually sufficient power, from being used to run the airmini ...

My $400 c266 should be able to run this ... I think I need to modify the resmed adapter so it can.. Or what ? The problem seems to be the resmed dc adapter.

[Jas_williams]

I plugged the airmini's 65w dc converter into the socket in my car ( the airmini not attached ) -- and the indicator light glows green.

Then I plugged the same dc converter ( again no airmini attached ) into the c266 -- and the light glows amber for 4-5 seconds then goes off.

So - now I will go to sleep using the same c266 battery powering my old resmed s9 for the 4th night without recharging... Doesn't that show that the battery is pushing out enough power for it to work ???? To me it looks like the converter is over engineered to the point that it prevents what is actually sufficient power, from being used to run the airmini ...

My $400 c266 should be able to run this ... I think I need to modify the resmed adapter so it can.. Or what ? The problem seems to be the resmed dc adapter.

i suspect the resmed adapter measures the output voltage of the 12v accessory socket with a normal lead acid battery this will be approx 12.6 volts with a fully charged battery and somewhat lower when it is almost discharged. I suspect the C266 is putting out 12.0 volts which the resmed adapter assumes the batter is not sufficiently charged and shuts down (To avoid discharging a lead acid battery completely which can cause it to fail)

I am not sure what the solution to this issue is.

[CapnLoki]

I plugged the airmini's 65w dc converter into the socket in my car ( the airmini not attached ) -- and the indicator light glows green.

Then I plugged the same dc converter ( again no airmini attached ) into the c266 -- and the light glows amber for 4-5 seconds then goes off.

So - now I will go to sleep using the same c266 battery powering my old resmed s9 for the 4th night without recharging... Doesn't that show that the battery is pushing out enough power for it to work ???? To me it looks like the converter is over engineered to the point that it prevents what is actually sufficient power, from being used to run the airmini ...

My $400 c266 should be able to run this ... I think I need to modify the resmed adapter so it can.. Or what ? The problem seems to be the resmed dc adapter.

It certainly sounds like the airmini converter is designed a bit differently than the s9 converter - you might try exchanging it to see if its caused by a small manufacturing variance. We've had cases where one batch of batteries failed with undervolt during startup, and then replacement units worked fine. You might also try measuring the voltage to see if it goes down to maybe 11V, although it probably happens too quickly to catch on a basic VOM. You might also try altering the sequence, perhaps plugging in the converter with the pump, and then adding the pump.

I'm still curious about the age of the 266, and how often its been used.

[palerider]

Then I plugged the same dc converter ( again no airmini attached ) into the c266 -- and the light glows amber for 4-5 seconds then goes off.

maybe your battery is shutting off the output if it doesn't detect enough power draw. Some do that.

[rcobourn]

Then I plugged the same dc converter ( again no airmini attached ) into the c266 -- and the light glows amber for 4-5 seconds then goes off.

maybe your battery is shutting off the output if it doesn't detect enough power draw. Some do that.

It's supposed to be able to power smaller devices like DVD players. I think jas_williams has it right, the DC converter is detecting low voltage and shutting down.

[shb]

I plugged the airmini's 65w dc converter into the socket in my car ( the airmini not attached ) -- and the indicator light glows green.

Then I plugged the same dc converter ( again no airmini attached ) into the c266 -- and the light glows amber for 4-5 seconds then goes off.

So - now I will go to sleep using the same c266 battery powering my old resmed s9 for the 4th night without recharging... Doesn't that show that the battery is pushing out enough power for it to work ???? To me it looks like the converter is over engineered to the point that it prevents what is actually sufficient power, from being used to run the airmini ...

My $400 c266 should be able to run this ... I think I need to modify the resmed adapter so it can.. Or what ? The problem seems to be the resmed dc adapter.

i suspect the resmed adapter measures the output voltage of the 12v accessory socket with a normal lead acid battery this will be approx 12.6 volts with a fully charged battery and somewhat lower when it is almost discharged. I suspect the C266 is putting out 12.0 volts which the resmed adapter assumes the batter is not sufficiently charged and shuts down (To avoid discharging a lead acid battery completely which can cause it to fail)

I am not sure what the solution to this issue is.

Jas_williams YES ! IT LOOKS LIKE YOUR GUESS IS SPOT ON !!

Here is the specs of the C266 ( i eventually dug out the documentation from archives).




As you can see - the C266 CPAP battery is actually outputting 11.1 VOLTS --- and the AIRMini DC converter is not going to accept that ! Even though the Resmed S9 has no problems with the same battery.

I'm not giving up that easily. The battery has enough power to drive it - just is outputting 11.1 volts ( but plenty of amps and thus plenty of power).

The next thing I tried was using an old Inverter I had in a bottom drawer. Inverter converts DC to AC ..

And the AirMini does run happily from the C266 using that inverter (see picture) From memory that only cost about $30 when I bought it , so is actually considerably cheaper than buying the Resmed DC converter .




But - converting battery (DC) to AC then back to 24v DC to run the Airmini - seems to me to be a very inefficient way to do it, so I expect that the battery would run for fewer nights that way..

Here's my plan .... I will use the S9 DC converter to run the AirMini. It clearly does not have the internal circuitry to cut out when it detects only 11.1 volts. And it happily steps it up to 24volts ( as proven by it running the S9).

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 ???

[shb]

The take home messages :

1. If you have a Resmed Airmini and you buy the Resmed DC converter for it -- DO NOT EXPECT it to just work with your existing cpap battery (without checking the battery specs). Even if that battery happily runs other Resmed devices. The reason is - the Resmed Airmini DC converter is LESS tolerant of the voltage specs of the battery than previous Resmed DC converters .

2. If anyone wants a RESMED AIRMINI DC converter - I have one for sale ... I will also try to return it for a refund, but I dont like my chances on that...

[BTS]

I thought I posted this here guess I didn't .... Battery pack : https://buyminicpap.com/products/batter ... or-airmini

[shb]

I thought I posted this here guess I didn't .... Battery pack : https://buyminicpap.com/products/batter ... or-airmini

Yeah.. I know about that battery... But it doesn't help with my problem -- which is getting an existing C266 battery ( that I already own ) to work with the Airmini