+- Apnea Board Forum - CPAP | Sleep Apnea (https://www.apneaboard.com/forums)
+-- Forum: Public Area (https://www.apneaboard.com/forums/Forum-Public-Area)
+--- Forum: Main Apnea Board Forum (https://www.apneaboard.com/forums/Forum-Main-Apnea-Board-Forum)
+--- Thread: Resmed S9 optimal battery runtime configuration questions (/Thread-Resmed-S9-optimal-battery-runtime-configuration-questions)
Resmed S9 optimal battery runtime configuration questions - Crimson Nape - 09-08-2017
I have a Resmed S9 and the 90 watt 12-24 volt DC power supply. I understand that there is rarely a 1:1 trade off, thus my questions. My questions are in 2 parts. Ultimately, I'm looking at the most effective configuration.
Part 1 - If I use two 12 volt batteries of the same size which would be the most advantageous wiring method, in series. in parallel, or no difference?
Part 2 - What would be a better configuration; two 12 volt "X" amp hour batteries wired in series to produce 24 volts, or one 12 volt at double (X*2) the amp hour ranting of the 2 smaller ones.
RE: Resmed S9 optimal battery runtime configuration questions - Gary1of2 - 09-09-2017
Ifvi am getting you question right. I know for instance when we have a 24 volt scissor lift we get longer battery life using 4 -6 volt deepcycle batteries wired in series for24 volts. I think the same applies to your question.
RE: Resmed S9 optimal battery runtime configuration questions - Crimson Nape - 09-09-2017
Thanks! I think srlevine1 answered my question in another thread (Referenced Thread). There is some energy loss whenever you change it. I'll experience less loss if I input 24V into the power supply as opposed to inputting 12V and letting it convert it to 24V.
RE: Resmed S9 optimal battery runtime configuration questions - OMyMyOHellYes - 09-10-2017
There is not enough energy loss with ResMed's 12-24 V DC converter to worry about. I had a friend once that referred to a syndrome called PII (Preoccupation with Inconsequential Increments). I think this falls under that category.
If ResMed was not of a mind to force their customers into buying their converter to make the unit run, I would say sure, go with 24 V direct. But since you can't go 24 direct, then just use 12 and don't worry about it. Without heated humogrification, the S-9 on the converter is really energy efficient anyway. I can safely get 8 nights out of a 35 AH battery on it.
OMMOHY
RE: Resmed S9 optimal battery runtime configuration questions - Crimson Nape - 09-10-2017
A big Thank You for that information. I didn't know what the conversion loss would be.
Red