12VDC to 24VDC converter or a 12VDC to 120VAC inverter

[ProVega]

I would like to use my VPAP machine while camping and I have noticed there are at least two ways to run it from a standard 12V battery. While operating my ResMed S9 from a battery, which would use less current, a 12VDC to 24VDC converter or a 12VDC to 120VAC inverter? I would like to use as small and portable a battery as possible. Low cost is a consideration. I know I can buy a battery which will power my S9 directly but, it costs from $300.00 to $700.00. That's just too much for me to spend. I would like your opinion on what's best for operating away from AC power. Thank you, Leo

[squid13]

I use one of these along with my battery for my home backup power. https://www.cpap.com/productpage/DC-Con ... hines.html

[CapnLoki]

I would like to use my VPAP machine while camping and I have noticed there are at least two ways to run it from a standard 12V battery. While operating my ResMed S9 from a battery, which would use less current, a 12VDC to 24VDC converter or a 12VDC to 120VAC inverter? I would like to use as small and portable a battery as possible. Low cost is a consideration. I know I can buy a battery which will power my S9 directly but, it costs from $300.00 to $700.00. That's just too much for me to spend. I would like your opinion on what's best for operating away from AC power. Thank you, Leo

The traditional value of inverter efficiency is 50%, but most newer models will claim 90%. Unfortunately, that is usually near peak power and under more typical conditions the inverter plus the power brick together are at about 60% efficient.
viewtopic.php?f=1&t=92230&st=0&sk=t&sd=a#p854963
For Respironics machines that can take 12V directly, its a no-brainer, but for ResMed you have to assume the converter is about 85-90% efficient, and since it costs $85, you have to do a cost/benefit analysis.

You don't mention what type of camping you're doing - if you're carrying in, obviously you can't take a large lead-acid battery, and you probably want a small lithium based battery. I'm guessing the 12-24DC converter will allow you to stretch the time of a small lithium battery and end up cheaper. On the other hand, if you're "car camping" a not very expensive deep cycle lead-acid battery can easily run a CPAP with humidifier for two nights, even on an inverter.

BTW, although you can get fairly cheap (under $50) inverters, they are cheaply made, have a less than stellar failure rate, and often have a noisy fan.

Some background:
http://www.resmed.com/assets/documents/ ... lo_eng.pdf

[Bama Rambler]

Unless you're willing to get a TSW (True Sine Wave) inverter I'd go with the 12v to 24v converter.

[CapnLoki]

Unless you're willing to get a TSW (True Sine Wave) inverter I'd go with the 12v to 24v converter.

Why? There should be no problem using a Modified Sine Wave (MSW) inverter with the S9 power brick. I've use MSW inverters for years and have only had a few devices (usually power tools with motors) that have had an issue. There shouldn't be a problem if the AC power is then fed through a power brick. Admittedly you're more likely to get high quality in a TSW inverter, but there's nothing inherently wrong with MSW.

That said, I'd still lean towards the 12-24V converter instead of an inverter.

[palerider]

Unless you're willing to get a TSW (True Sine Wave) inverter I'd go with the 12v to 24v converter.

that all depends on what system you're using:

http://www.resmed.com/assets/documents/ ... lo_eng.pdf

s9, modified sine wave 150 watt is fine according to resmed. even with humidifier.

[Goofproof]

You are powering a very costly machine that would like the safest power source you can provide. If I had one, it would be running on a full sine wave UPS, even when hooked up to the house mains.

That said, the next safest would be two deep charge 12 volt wired in series for 24 volts. If I had to drag that costly of a machine around, I would buy a more power friendly APAP to use for travel, not a Resmed ever....

By using power converters you are betting nothing is going to malfunction, on a machine that has little built in to provide safety for your equipment. Motors and lights are forgiving of power changes, things with circuit boards, not so much.

The great outdoors are really nice, but now I stay close to home due to hezlth and aging concerns. I accept my limitations, not that I like it, but my days of rock climbing our over, it's too hard pulling the wheel chair up to the top.

[palerider]

generally, I'm happy to accept the manufacturers recommendation as to what their machines need, instead of trying to second guess them.

switch mode power supplies, like that in the resmed brick, really don't care about sine wave power. inductive power supplies (read, big heavy transformers DO care, the harmonics caused by the square waves cause them to overheat.

see also:
http://wiki.answers.com/Q/Is_square_wav ... ic_devices
http://electronics.stackexchange.com/qu ... e-computer

[archangle]

You are powering a very costly machine that would like the safest power source you can provide. If I had one, it would be running on a full sine wave UPS, even when hooked up to the house mains.

If anything, switching power supplies like the S9 power brick run better off a MSW inverter than a true sine wave.

The pure sine wave inverters are more complicated, and may be less efficient than a MSW inverter. However, there are good and bad designs in MSW and pure sine inverters.

[Goofproof]

You are powering a very costly machine that would like the safest power source you can provide. If I had one, it would be running on a full sine wave UPS, even when hooked up to the house mains.

If anything, switching power supplies like the S9 power brick run better off a MSW inverter than a true sine wave.

The pure sine wave inverters are more complicated, and may be less efficient than a MSW inverter. However, there are good and bad designs in MSW and pure sine inverters.

That's why a cheaper apap for camping run straight off a 12volt deep charge battery is a best option, saving the costly machine home safer. Jim

You go adding other power solutions and the unknown factors can become costly. Circuits can be engineered correctly, but cost becomes a factor and quality goes out the window.

[ProVega]

Thank you to all who took the time and interest to answer my question. I was overwhelmed by the depth of your responses.
I had posted this question just before needing to make a decision on a device to purchase. We were leaving for camping in a few days. Without the benefit of your wisdom I bought a 175W inverter. It was manufactured by Go Power. It along with the battery out of my Chevy Tracker worked just fine.
Thanks again,
Leo

[larryperryau]

I've got my resmed s8 on D'Cruz power but having trouble getting it to go to the welcome screen and start working. Got it going once, but cannot get it going again. Are there any sequence of buttons that will help me go to the start up.

[Guest]

I've got my resmed s8 on D'Cruz power but having trouble getting it to go to the welcome screen and start working. Got it going once, but cannot get it going again. Are there any sequence of buttons that will help me go to the start up.

Not sure what a

D'Cruz power

is but is it fully changed?

[SleepyToo2]

I've got my resmed s8 on D'Cruz power but having trouble getting it to go to the welcome screen and start working. Got it going once, but cannot get it going again. Are there any sequence of buttons that will help me go to the start up.

If you read the thread you will see that getting Resmed machines to work maybe a little complex because of the 24 volts required. I suggest you start a new thread with the name of the power source in the title - you might get more attention that way. Also, explain what the D'Cruz power actually is.

[terrydk]

ResMed still hasn't released the DC to DC converter for the Airsense 10 and I need to find a power source from my 12V battery supply in my travel trailer to power it. I sent ResMed an email asking about using a modified sine wave inverter but haven't heard anything back yet. I don't use the humidifier or the heated tube. I found a couple of 12 to 24vdc converters on Amazon for $25-$35 that look like they would work. Does anyone have any idea of the size of the power plug on the Airsense 10? I also found a cigarette lighter plug type on the internet that has the option of several different adapter tips but don't know which one I need to fit the Airsense 10.