S9 on an inverter

Hi All

I’m on my way to spend 2 weeks of car camping. I needed an inverter for my S9. Here are a few spec’s on what I bought and tested.

CPAP - ResMed S9 with humidifier
Set to 12 cm of h2o
Inverter - AIMS 300 Watt PURE Sine PWRI30012S $ 99.00
http://www.aimscorp.net/PWRI30012S.htm
Power Supply adjusted to 12.8 volts

I measured the following with a Aero Flight meter. http://tinyurl.com/yo9w2l

Inverter on but no load 0.5A
Inverter and the S9 - not running = 0.8A
(So remember to unplug the inverter from the battery when not in use)
Humidifier off, open hose = 3.7A
Humidifier off, mask on = 1.5 to 2.5 (10 to 30 watts)
(It was bouncing between those numbers as you inhale and exhale)
Humidifier on max, open hose = 8.2A (106 Watts)

So with the humidifier on at 50% of max, in normal use, (3 amps) a 45Ah car battery you can make it all night (10 hours). It will bring the battery down to 80% of it’s max charge.

http://www.gizmology.net/batteries.htm

Bob Ross

Hello: Bob


It sounds like you might have something there,I've been looking for a backup power source for the same reasons, camping and just in case of a power outage. Let us know how the s9 with the inverter worked for you during your camping trip,i'm sure other forum member's would also be interested in reading your followup posting.
good luck on your camping and i hope that you have a safe and great time



Phil

If you are going to use a vehicular battery make sure that at the very least it is a sealed one, unvented, or the first time you light up you are going to get more than a blue flame. Deep discharge motorcycle or marine batteries are great and they make a carrying case that is acid resistant for them and has a handle. Get a case large enough and you can stick a wee charger and perhaps an inverter inside that case as well. Make sure you understand the battery specifications and the charger specs as well. And make sure you buy a quality inverter and fuse the heck out of everything (and solder the connections please). I made one years ago and installed an inverter epoxied to the side of the box and a DC cigarette lighter type socket in the wall of the case as well. Worked like a charm until I left it somewhere and it disappeared. Used it for powering up ham radio equipment (shortware for short periods of time and VHF/UHF radios for Looooooong periods of time.) Then used it for charging my camera gear as I recall. That's when it did a disappearing act on me. Again, the gases emitted by some batteries are noxious and explosive. Make sure you know what you are doing.

torontoCPAPguy wrote: perhaps an inverter inside that case as well.

A wee nitpick: don't put the inverter somewhere where there won't be sufficient airflow to cool it. Power FETs don't like getting too hot, next to a big battery is doubleplus unhappy.

I like your idea of attaching it to the outside of the case better.

I have a big deep-cycle marine battery that I intended to have on hand for backup if I needed it. Unfortunately I let it sit too long and now my big charger can't get it up (charger started at around 8A, it took about an hour to climb to about 3A where I let it sit for over a full day - it didn't budge any farther, I disconnected it because I lost my nerve running it that long. Same charger used to be able to bring it up from pretty well depleted when I used it for a parade float. seems I damaged the battery somehow.). For the occasional home power failure I have one of those car jumpstart batteries; my S8 would run about 5 hours on it with the Resmed DC adapter. I expect my S9 would run longer but of course they don't have the DC cable available yet (wonder what's taking so long, it's not like a DC-DC converter is rocket science).

There's an excellent, but rather complex, article at myresmed.com

Good info on the S9.

Typically a car battery is for supplying a large bursts of power and not a deep discharge. (Some can do both high cracking power and deep discharge) but typically not. You can ruin a normal car battery by deeply discharging it.

Robert

reitzell wrote:Good info on the S9.

Typically a car battery is for supplying a large bursts of power and not a deep discharge. (Some can do both high cracking power and deep discharge) but typically not. You can ruin a normal car battery by deeply discharging it.

Robert

That is correct - Only deep cycle batteries are built to withstand the abuse of a deep discharge. I picked a "car battery" as an example.

Bob

We start the drive to Oshkosh in the morning. Sat night it's on the inverter! More info later.

Bob

Enjoy Oshkosh! Haven't been able to do Oshkosh (EAA air show, biggest in the world) for about 10 years now.

If at all possible, don't run the humidifier heat. In a camping situation, especially during a Wisconsin summer, you may find that passover humidification is enough. It will save you a lot of battery wear and tear.

At least though, you did your homework, and did all the right stuff!