Using a Resmed S8 on 12V power

[billbolton]

Does anyone have any technical details on the Resmed DC-12 adapter for the S8 CPAP machine??

The DC-12 is the adapter that is supposed to go between an automobile cigarette lighter outlet, or airline seat low voltage power socket (etc) and the S8.

I'm facing a 7 week vacation trip around Europe soon and it looks like I will end up carrying several different power supplies/adapters for CPAP, laptop, camera battery recharger, mobile phone etc, and I'd like to see if I can rationalise the number I really need to carry.

Does anyone have any experience is powering an S8 from a nominal 12 Volt DC power supply without using a DC-12 in the circuit?

Cheers,

Bill

[MaskedMechanic]

CPAP.com says "A Resmed DC-12 Converter For S8 Machines must be used with the 12 volt jack. Any other cable will likely cause a machine failure.

This humidifier cannot be run off 12 volt power. If a machine is powered by 12 volts, the heated humidifier will not run. If a cpap is powered by 110 or 220 volts it will power the heated humidifier. A 110 volt pure sine wave inverter hooked to a 12 volt battery can be used to power a machine and this humidifier."

Take it to the bank.

[billbolton]

CPAP.com says "A Resmed DC-12 Converter For S8 Machines must be used with the 12 volt jack. Any other cable will likely cause a machine failure.

That is indeed the standard wisdom, but its sounds so much like the "use our adapter or else" warning that many electronic kit manufacturers hand out (even when there is no engineering reason to do so) that I'm wondering if anyone here actually knows what a DC-12 does!

Resmed seem to be quite reticent in yeilding any information about it!

Cheers,

Bill

[billbolton]

Well, I bought a DC-12 and it came with zero information of any sort. Anyway, I set up a test rig with available DC power supply on the input side and was able to determine that the output is regulated to a constant 12.5V DC over a wide range of input voltages from 12 to 26 volts.

The S8 is wired for NEGATIVE voltage on the centre pin of the low voltage power connection, which is the opposite of the normal wiring convention for that type of low voltage connector.

I also discovered that you really need to be watching what you do when you plug the low voltage connector into the back of the S8.... doing it by "feel" can be misleading. The two pins on the mains connector are the same size as the single pin on the low voltage connector.

My first attempt to plug in the low voltage connector from the DC-12 by feel resulted in nothing at all happening. I thought I might have a faulty DC-12 or S8, but when I looked over the back of the S8 I saw that I had plugged the 12V connector onto one of the mains plug pins. Fortunately this doesn't create a power circuit with anything in the S8, so there is no risk of damaging either the DC-12 or S8 by doing this!

However, the possibility of this happening is something that could have been covered off in an instruction manual, but there nothing about it in my S8 manual and the DC-12 didn't come with any instructions.


On a separate by somewhat related matter, I have had confirmation from another S8 user that the TeleAdapt InFlight Power Adapter (inverter) will power an S8 satisfactorily (on mains power) from the low voltage EmPower socket available at many airlines seats. British Airway and Cathy Pacific are apparently quite happy to support in-flight CPAP operation using this unit. I'll be using one when I fly to Europe with BA later this year.

Cheers,

Bill

[vicinsb]

I don't know if this is the same thing that you guys are discussing, but I am wondering if my REsmed S8 Vantage can be used while camping? There are no hook-ups, but we do have a generator and a small RV. Do I buy the Resmed DC12 converter and will that work in this situation? I only do this once a year for 3 nights. Any input would be greatly appreciated as the camping trip is coming up in a few weeks. Thanks!

[toto]

it seems you are happy with the escape. I have pestered the place with my order and they are going to offer me the compact or 420G. I want a quiet operation. How is the escape? Is it quiet?

I think I will ask them for my order and see what the price is here vs them.

[billbolton]

There are no hook-ups, but we do have a generator and a small RV.

If by generator you mean one that delivers your local mains voltage (~120V AC I guess in your case) then you should just be able to plug your S8 straight into the mains output socket on the generator. If you use an H3i humidifier with your S8, you will be able to run that as normal.

Do I buy the Resmed DC12 converter

You only need a DC-12 if you don't have a main power source available and need to run your S8 off battery power. The DC-12 comes with a "cigarette lighter" style plug fitted for connection to the battery power source, but can be easily adapted to any connector.

The general advice given for CPAP operation from battery is that you should not use the same battery that you need to start a vehicle for running your CPAP. Otherwise, if you run the battery down too far you may not be able to get out of whatever remote are you might be in.

So, if you want to run your CPAP off battery power through a DC-12 and have an RV with an additional battery just for running accessory devices, you'd be OK to use a DC-12 to run your S8. Note that when running an S8 off a DC-12, you wont be able to use the H3i humidifier

Cheers,

Bill

[billbolton]

I want a quiet operation. How is the escape? Is it quiet?

Yes, very quite. I use an S7 Lightweight at home and and S8 Lightweight/Escape while travelling. I'd rate the S7 as very quiet and the S8 and even quieter!

Cheers,

Bill

[dsm]

http://www.internetage.com/cpapinfo/s8- ... index.html

I did the above simple test the last time someone claimed the S8 needed special dc power box.

The only issue with the S8 range is to make sure the dc plug is the correct type & as already mentioned, the negative is on the center pin. 12vdc off a 1.5amp source is very adequate. NOTE, with just 12vdc the humidifier won't activate but it can be connected.

If using an inverter (12vdc to 115vac) make sure it is a 'pure sine wave' inverter as the square wave type will damage the S8 power supply. The inverter will allow the humidifier to work.

DSM

[tdehnke]

Hi guys,

Have any of you run your S8 without the DC-12, just going staight to a cig lighter.. if so has it been good for you for several nights?

We have a large dual deep cycle battery system on our trailer, so I have lots of current

Has anyone found a voltage that the S8 stops working at - ie 10.5 etc

[billbolton]

Have any of you run your S8 without the DC-12, just going staight to a cig lighter.. if so has it been good for you for several nights?

Will it technically work if wired correctly... probably.

Is it a good idea given that putting reverse polarity voltage into an S8 will stop it instantly and mean a trip back to the factory... IMO, no.

A DC-12 does a number of things including managing variations in the battery terminal voltage and providing a well regulated 12V DC output of the correct plug polarity to an S8. The cost of a DC-12 compared to the cost of an S8 is small, and the protection is provides is well worth it.

Cheers,

Bill

[Bearded_One]

From ResMed Tech Note titled "Powering ResMed Products With Batteries":

Requirements for ResMed flow generators

Late model flow generators

For flow generators manufactured in 2000 or later, there is no special requirement with regard to inverter type. Any modified sine wave inverter with a power rating of 150 watts or more is
suitable.

Note: VPAP II units require an inverter rated at 200 watts. Refer to the table below.

Early model flow generators

For flow generators manufactured in 1999 or earlier, we recommend the use of a Powerbox PS-200-2 inverter. This model is also branded as Motormate PS-200-2.

Requirements for ResMed humidifiers

For use with the HumidAire™ 2i or HumidAire™ 3i, a pure sine wave inverter with a continuous power rating of 200 watts is suitable - refer to the table below.

Warning Other ResMed heated humidifiers must not be used with inverters. Damage to the
unit or serious injury to the user may result.

...

Using a [DC] converter to power your CPAP

Several S8 CPAP devices have a 12 volt DC power input which enable them to run from a 12 volt or 24 volt battery using a ResMed converter, P/N 33942.

• This converter is more efficient than an inverter.

• The converter provides electrical protection to the CPAP device in the event that the adapter leads are connected incorrectly to the battery.

• The converter provides regulation of the battery voltage: a fully charged battery has a terminal voltage of 13.5 volts and will reduce as the battery is discharged.

• The converter will shutdown automatically when the voltage drops below 10.5 volts for a 12 volt battery, or 21 volts for a 24 volt battery. This will protect the battery from damage
due to being allowed to fully discharge.

• The converter provides electrical isolation to the CPAP device.

[Shadowatcher]

I tested my S8 elite with a 12V booster battery that I use to provide 12V DC for field applications. I built my own cable with no isolation and the S8 runs just great with it. My booster battery has a series of lights on the front to tell you when the battery is getting low.

Shadowatcher

[j.a.taylor]

I'm facing a 7 week vacation trip around Europe soon and it looks like I will end up carrying several different power supplies/adapters for CPAP, laptop, camera battery recharger, mobile phone etc, and I'd like to see if I can rationalise the number I really need to carry.

Ah the joys of our technological living. All of our equipment that makes our life faster, more efficient, more comfortable.

Then, when we're traveling, we have to figure out how to carry it all. Spend time searching for the right baggage, new gadgets to empower our trip . . .

I love it!

Have a great vacation Bill!

[Guest]

Hi there,
I own a ResMed S8 Elite and was told I needed to buy the adapter in oder for it to work on a sail boat I'll be cruising on in June. I was told the boat has 12&24 watt power, so will this adapter from ResMed be enough?
Any/all help greatly appreciated!

Thanks!
Al

alborrelli @ gmail.com