I got the equipment and performed an overnight test and thought you might be interested in the result: it worked, but was not w/out its problems. I'd like to thank remstarcpap for helping me pick out the equipment. The first time I tried to perform the test, I hooked everything up but when I plugged...

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It'd be great if I knew that I didn't have to buy hardware that I already have. Specifically the NOCO genius5 when I already have a maintainer and a 2A, 4A, or 6A car charger.

I'm on the edge of buying an AGM battery but I need some straight answers about charging them. I've been told that car chargers will ruin the ML35-12 - 12 Volt 35AH SLA AGM MighyMax, but I've also been told that my battery maintainer (750mA) is safe to use. But I also have a quick charger that can p...

I know, very broad question, but I've got a lot to consider. I think the biggest consideration is shelf life, since going on 8 years of having a CPAP, there has only been 1 night I had to go the entire time w/out breathing. (But the way things are going, I'm sure there'll be more and they'll be more...

I the voltage drop issue is why I would recommend using a DC to DC convertor such as the one Resmed sells. Make sure it you are always within the input range, and your output will be constant. 13 cells in series seemed like a fair bet for Resmed in my example above. If the 1.3 V is accurate, you ar...

So you took 18Ah/16 cells =1.1Ah per cell. Trouble is, we have the same number of hours (8) and the same number of amperes (2.2) in each cell. Cells in series increase voltage, not amps. If your starting numbers are correct, each D cell will need to supply the full 18 Ah. If you want 1.1 Ah per cel...

That's... strangely disappointing. If a CPAP draws 53W then a 24V supply will average 2.2A. Over an 8 hour period, that means almost 18AH. So each of those 16 batteries will need to deliver 1.1AH. A lot of LR20s are rated at more than 10AH, but I heard that even pessimistically, you can expect 2AH ...

25% would have been plenty

I see. So to get the charge you want, you have to adjust the current appropriately. How about a switching supply, that allows for 10s at 5A then then nothing for 23s? It'd be a honking big capacitor bank though, even if they are electrolytic. Oh well, I guess I know now why no one came up w/that ide...

I just looked up the datasheet for a Duracell Coppertop D-cell battery. The largest current application they give in the curves is 2 amps. At this draw, the single cell voltage drops to 1.1V in 30 minutes, and to 0.8V after two hours. IMO, this type of battery lacks the power density required for t...

In that case, once I find out what to do, I'll keep the how questions to a minimum. And I have a pretty good idea of how to do it, but that presumes the what . Beyond what I've already discussed, I'd think I'd be building a precision regulator powered by a couple of AAs. But to know if that's even f...

In that case, a few other issues get brought up: I don't think the 8 LR20s that would get my 12V would have the required charge. I can still use the same number of batteries in parallel, but I also don't have much experience designing for dry cells that are in parallel, so I don't know how uneven vo...

It's not something that I can throw together on short notice, but something that will cost as little as possible, since whatever I get will probably expire before I can use it. If I have to spend 30$ every 5 years for something I never use, that's a bargain. Ok, judging from SleepGeek's comment, it ...

I've seen a lot of talk about batteries for different needs (camping, traveling, etc.) but I'm more concerned w/the situation where I have to spend the entire night w/out power. I've been researching various threads and there are some pretty good solutions, but it seems to me a couple of dozen LR20s...