[Equipment] Portable generator to power S9

[Ghost1958]

Hummm im not sure if a Cpap machine power brick is different than a computer one in what it takes but we have ran laptops off generators on ac for all kinds of things for a week at a time.

But if the Generator wont do the trick then I guess its two car batteries, a battery charger AND a small generator for the wife and me this winter. Our power outages are for days not hours out here where we live. Reckon if the generator cant be used to run the pap machines off of then itll have to power a battery charger to recharge the two car batteries everyday till the outage is over.

Still dont see why everything else electrical from PCs to toasters tvs etc can be run off the AC side of a generator but a cpap cant. But im no electician either

[OMyMyOHellYes]

Can you use a portable generator to power an S9? I called ResMed technical support and they told me that you could NOT. Not sure if they just wanted to sell me a battery!

How much gas do it use and how much you got on hand? If there is a power outage of any duration and/or large geographic area, local sources of gasoline are going to be dead in the water too since gas pumps run off electric. They may have full underground tanks, but no way to get it into your car or cans.

Growing up in the country, we had a few widespread power outages of several days duration. I plan on having two weeks of reserve battery capacity for CPAP and a means to recharge the batts off grid.

OMM

[woozie38]

Hummm im not sure if a Cpap machine power brick is different than a computer one in what it takes but we have ran laptops off generators on ac for all kinds of things for a week at a time.

But if the Generator wont do the trick then I guess its two car batteries, a battery charger AND a small generator for the wife and me this winter. Our power outages are for days not hours out here where we live. Reckon if the generator cant be used to run the pap machines off of then itll have to power a battery charger to recharge the two car batteries everyday till the outage is over.

Still dont see why everything else electrical from PCs to toasters tvs etc can be run off the AC side of a generator but a cpap cant. But im no electrician either

I understand your problem. Use your generator to charge the batteries. A standard 12V battery is around 80~100 ampere hours. About 70% of which is available for use & a CPAP machine uses approx. 50 Watts or draws about 4 amps at 12V, without the humidifier, which means such a battery theoretically would power your machine for about 16hrs. I use a 150 A/hr AGM battery which is kept charged by the AC grid in conjunction with a 300W pure sine wave inverter. During a power outage this lasts up to 4 nights. PS. laptop computers run off their batteries and don't have a large power transformer. The problem is caused by a phenomenon known as hysteresis factor. Any appliance that has a large power transformer is in great danger when used on the uncertain power from a portable generator. The gear may well work for a while, but only until the transformer windings heat up, short and burn. At this point the rest of the circuitry is in jeopardy. I have burnt out a couple of transformers in this way.

[Galactus]

I don't want to get into a large argument over this but the fact is that the AC Adapter used on my CPAP machine is an exact copy of the AC Adapter used on many notebook computers nothing more and nothing less even manufactured by Astec a large supplier of AC Adapters for many computers. Further NB computers run off the power supply just as well as off their batteries. If you remove the battery and run the NB off the AC Adapter it runs just fine off a generator, as we do many times here in the winter when the power goes out. We also run our air compressors, air tools, and the whole rest of the house off backup generators, as well as a few different outside shops, some with direct hook up generators others with outside smaller units. If you are truly worried about the CPAP unit add a low end small UPS between the AC Adapter and the generator outlet, it will clean any possible power issues in the line.

[woozie38]

I don't want to get into a large argument over this but the fact is that the AC Adapter used on my CPAP machine is an exact copy of the AC Adapter used on many notebook computers nothing more and nothing less even manufactured by Astec a large supplier of AC Adapters for many computers. Further NB computers run off the power supply just as well as off their batteries. If you remove the battery and run the NB off the AC Adapter it runs just fine off a generator, as we do many times here in the winter when the power goes out. We also run our air compressors, air tools, and the whole rest of the house off backup generators, as well as a few different outside shops, some with direct hook up generators others with outside smaller units. If you are truly worried about the CPAP unit add a low end small UPS between the AC Adapter and the generator outlet, it will clean any possible power issues in the line.

Yes you are correct Galactus. It's only the equipment that run on low voltage broken down by a power transformer that risks damage from generator output. Especially if it's a multi tap transformer. As you say, power tools, refrigerators. washing machines & the like all run fine.

[Skypilot]

Can you use a portable generator to power an S9? I called ResMed technical support and they told me that you could NOT. Not sure if they just wanted to sell me a battery!

The short answer is NO you can't, but it depends on the generator. If your generator has permanent magnets instead of field coils, its a good chance it will produce suitable power. However most generators produce a sort of modified sine wave which is not suitable and will cause heat to build up in the power transformer of the PAP machine's power supply.The transformer will burn out. Any device equipped with a power transformer requires a pure sine wave power source. The alternative as you've been advised is to use an accumulator (battery), which is probably best anyway.

The power bricks that come with the CPAP machines do not use transformers - they are switch mode power supplies - no transformer.

Switch mode is much more efficient than a transformer and allows the the wide voltage range of 115 - 240 - you can't do that with a transformer; you would have to move a switch to use different tappings on the transformer.

[woozie38]

The power bricks that come with the CPAP machines do not use transformers - they are switch mode power supplies - no transformer.

True. Can you tell if switch mode power supplies can handle the rough power from a portable genset?

[Doc J]

There is still a transformer in a switch mode power supply, it is much smaller and lighter and works at high frequency. Just get an extra power supply brick and roll the dice and find out in real time. It will probably work and you can adapt if the first one blows up.

[Galactus]

It was late, I was tired, skypilot said what I meant lol. And DocJ added the correction. I was trying to say they are small supplies with small transformers and switchable supplies like our NB computers and are able to be run off generators. Add to that for about $25-$50 you can just add a UPS in the line to protect a computer or cpap supply from having an issue. Or as DocJ says have an extra supply on hand. One other thing to note if using it on a generator would be do not start the genny with the supply plugged in, start it, and then plug in the load. Also do not allow the genny to run out of fuel with the load plugged in. Both these points, startup, and shut down are when the voltages will vary and stability will be at issue and when devices are at risk the most, goes for all devices as well.

[Ghost1958]

Ok being stupid Ill try to figure this out with some help please since there are conflicting posts about it.
Short term outage is not what I need to deal with for two machines. A week to four weeks is possible. Doesnt happen that long often but it has more than once due to ice taking down power lines and trees. I can store gas for that long in 5 gal cans with stabil.
Which I would do because several times even getting out of here in a full size 4 wheel drive or a atv has been iffy to impossible due to downed trees.

Now if im reading this right If I get a small generator, and a surge protector, plug the cpaps into the surge protector I would be ok???
Assuming a small generator will run two Apaps with heated humidifiers?? I heat with wood so that isnt a problem. Dont care about running anything else but the Apaps at night.

But I do need to figure this out before weather gets nasty. On a fixed income and cant really afford to spend money this way then that way to try set up a long term power solution that will work without wrecking the machines.