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Hi, wonder if anyone can help me, I am looking for a DC power lead without the car lighter attachment for my Philips REMstar Auto A-Flex. I'm currently using an inverter and a leisure battery when caravanning and not hooked up to mains electricity. The inverter is exceedingly noisy but is worth it for a good nights sleep but it does drain the battery quite quickly.
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If you are good with a soldering iron you could make one.
Or you could buy one with a car lighter plug and get and car lighter extension lead, these normally have crocodile clips on the end. Just be careful with the polarity on both leads.
Trace the wires out with a multi-meter, or get someone to check it for you.
Do not mix the connections up when you connect it to a battery.
Sleep2snore said:
If you are good with a soldering iron you could make one.
Or you could buy one with a car lighter plug and get and car lighter extension lead, these normally have crocodile clips on the end. Just be careful with the polarity on both leads.
Trace the wires out with a multi-meter, or get someone to check it for you.
Do not mix the connections up when you connect it to a battery.
I'm not to bad with a soldering iron but where can I get the extension lead from? I've seen the lead with car lighter attachment but not the other one.
However I wouldn't want to damage my machine.
I got one from an AUTO parts company. Most car accessory shops should stock them or could get you one.
Wish I could remember where I put it, I could use it now!
It used to be with the tyre compressor, but I can't find it. 
A thing to watch when using DC power leads is some machines use the centre pin being negative instead of positive as in most cars these days, so be careful when connecting DC power leads.
Also car batteries are not the best to power a CPAP machine off as if the car battery is discharged more that 30% it can start to eat at the battery and dissolve the plates that supply the power. If using a battery t is best to use a leisure battery, these have heavier plates inside and can be discharged and then recharged without damage (you must charge them up after you use them or store them for any length of time) these batteries are designed for deep cycle discharge and recharge. They will not get dissolved so quickly and can be discharged 60-70% without any damage to the battery and can be run flatter if need be as long as you charge them right away.
Some machines you can use with a DC to DC adaptor, these adaptors allow you to run on 24vDC as well as 12vDC and will cut the power off if the battery gets lower that 30% discharge, they also protect against reversed polarity.
Unfortunately, the manufacturer has decided to stop making these adaptors.
Watch the polarity as a mistake will break the machine, there is a diode inside the machine that will blow an internal fuse if you get it wrong (if you are lucky) or it might do more damage. The fuse is tiny and not something most people could fix as they are usually soldered to the circuit board. Even if you could get one, I would recommend trying to fix it.
Hi, thanks for all your advice and I did a lot of research but in the end bought both parts compatible with my machine, suffice to say I no longer have to use a noisy inverter and the battery(leisure) lasts longer.
Some of these machines are 24VDC, such as some of the new Resmed machines, just to make life complicated.
You need a 12Vdc to 24Vdc adaptor. These are £100 + shocking cost for something so simple!
Hi found a USA company that has a large selection of power accessories for CPAP and BIPAP machines, I e-mailed them with the specs on my machine and they confirmed the connection cables I asked for to connect to a car cigar lighter socket and also direct leads to a leisure battery for holidays etc. Contact www.CPAP.com
Update to previous
Sleep2snore said:
A thing to watch when using DC power leads is some machines use the centre pin being negative instead of positive as in most cars these days, so be careful when connecting DC power leads.
By putting a bridge rectifier between the input connector and the unit, the polarity of the voltage applied to the input connector becomes irrelevant.
The polarity at the output of the bridge will always be the same.
The bridge could also be mounted as an external adaptor between the unit's connector and the voltage source.
I asked Resmed and got this link from them, still not cheap though.
https://mysleep.resmed.com/GB/en/Sleep-Apnoea/Accessories/AirSense-...
I suppose I could fit a 12v ciggy socket near where I sleep, and plug in one of those coke can type inverters, but as it will be running a motor, would it not need to be pure sine wave.
That is under debate, they said at a conference that it had to be a pure sine wave, now they have said in America that it does not have to be. Sometimes you just so not know what to believe.
A pure sine wave might be better for you and the machine, but if it is just now and again, I would not worry to much about it.
What I would do is ask ResMed, if they say it is fine to use a non-sine wave one that is fine, but I would get this in an email to cover yourself against damage. If you are not moving every day, I would buy a deep cycle battery, the power supply will cat off when the battery voltage drops below a certain level, but it might be to late to start your engine. Charge it up in tandem with a non-return diode and a charging circuit to keep it topped up.
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