Very nice project - thanks for the pictures! The problem that I have always had with Hobby King is their excessive shipping and handling charges - how much did they ding you for the parts that you ordered from them? I'm not sure exactly how much the shipping came out too, as my cousin ordered the p...

Well, we've had great success! My cousin got five days out of ONE battery. And we bought FIVE batteries! He took some excellent photos. Here they are. Please let me know if you have any questions. Components http://i689.photobucket.com/albums/vv257/GTSSportCoupe/CPAP/image1_zps8hw7qn0w.jpg~original ...

Can you provide a link to the battery? Sent from my SM-T350 using Tapatalk I did higher up in the thread, but here it is again. Costs $50USD from the hobby king USA West ware house. Very good deal. http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=72325 I bought this charger for it...

Received the Resmed DC/DC Converter today! I plugged it in to a bench top current/voltage limiting power supply so I could easily limit the input current (just in case anything went wrong). Started at 12V and right away the adapter output 24V on two of the pins. (no CPAP connected). With no load, th...

Forgot to mention, the batteries weigh in at 3lb each. So 1350Wh at 15lb total weight.

Well, the ResMed DC/DC Adapter is enroute. I'll report on my testing with it once I receive it. Fingers crossed it works ok with the batteries, if not I'll use the DC/DC converter I already bought to feed 24V into it. I tested the real world capacity of the batteries we bought. The are 270Wh each!! ...

well, like I said, the converter says it's good for 12 to 24 volts dc input. like most boost converters, it's not that picky about what it eats I think there is more to it then that. It has some smarts with regard to the battery voltage it expects. Here is a quote from some of the documentation I'v...

I never saw the point of reinventing the converter whose only problem was a slightly high price tag. the advantage (possibly) in this case could be a better form factor, and lighter weight, the resmed converter is fairly heavy. In my case I was hoping to know if it would work with the slightly high...

Why not pick up a respironics machine as a travel machine/backup? Unfortunately, you missed a recent sale by our sponsor that was selling them brand new for $310. They are also available on amazon.com. And some members here probably have suitable machines for sale. Respironics run on 12 volts and o...

Lots of stuff here - First, I've never heard that the 12/24 converter is inefficient, I've always guessed 90%. I've assumed it handles any voltage between 12 and 24 but could be wrong. Instead of LiPo why not LiFePO4? You can get a 4S pack with BMS that has a good 12v output. Or, get Philips 560 ap...

Thinking out loud here. Perhaps what I'll do is purchase the ResMed DC/DC converter. I'll use my 24V DC/DC converter to provide 24V input to the ResMed converter. Two DC/DC converters in a row is not as efficient, but probably not that bad at the end of the day. The one I bought is 92% efficient. Th...

Hi All. I am new here. I'm an electronics designer trying to help my cousin build a portable battery setup for his ResMed S9 CPAP machine. He needs a very light weight and efficient setup that will last for five days. He will be hiking part of a very long scenic trail and has been hired to do landsc...