CPAP machine w/ inverter. How much power?
Hi Folks, A little background. Not new to RVing, but starting to deal with battery issues more, now that I have a week long music festival coming up w/ no hookups. I decided that after last year, n...
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Thanks to everyone for all the replies. Bringing up electrical issues reminds me of all the back and forth photographers do on forums regarding digital imagery ( I am a pro photographer in one of my jobs.) It also reminds me why I dropped out of college 30 years ago while studying electrical engineering!
Long story short, I'll have a day or two to test this out before camping next week, and my brother said that if the CPAP machine doesn't work, oh well, he'll be ok w/o it for a week. I'll just bring along and AED, case he codes in the middle of the night :)
So, more for curiosity's sake, rather than needing hard answers, some responses just don't make sense. PianoTuna, I have gained a lot of info reading your posts this these past few months, so thanks again, but in regards to your statement "2 amps @ 120 volts via an inverter may translate to 20 amps @ 12 volts", OK, I guess I see the math, but if so, how the hell does anyone run anything in an RV with a converter? If a 2 amp cpap kills( brings below 30 or 40%)2 Group 27 bats (approx 190 AH correct?) in about 5 hours, how are people using other things that draw a boatload more current? Never mind all the people who successfully use their CPAPs?
I also have seen you post that graph, and I find it interesting. It would be nice if they spread out the x axis more, so I could see differences between 0 and 20 hours better, and also if they started with a higher SOC on the battery, say somewhere between 35-50%, where I would bet a lot of RVers take their bats down to before topping off.
Also, as the curve is so steep the first few hours or so, does it matter so much whether my charger is 20 amps, instead of 40 or 50, or even 70? Does the 20 amp setting on my Schumacher charger mean that 20 amps is the max, or does it go higher at the start, then settle down at 20, then gradually to trickle as it gets closer to full?
I have read hundreds of posts of most people bringing their bats from 50 to 90 percent with their gens, with run times approx 3 hrs a day. Your chart says that is improbable, if not impossible with even a 55 amp charger/converter.
Something's not adding up. What am I not seeing?
Long story short, I'll have a day or two to test this out before camping next week, and my brother said that if the CPAP machine doesn't work, oh well, he'll be ok w/o it for a week. I'll just bring along and AED, case he codes in the middle of the night :)
So, more for curiosity's sake, rather than needing hard answers, some responses just don't make sense. PianoTuna, I have gained a lot of info reading your posts this these past few months, so thanks again, but in regards to your statement "2 amps @ 120 volts via an inverter may translate to 20 amps @ 12 volts", OK, I guess I see the math, but if so, how the hell does anyone run anything in an RV with a converter? If a 2 amp cpap kills( brings below 30 or 40%)2 Group 27 bats (approx 190 AH correct?) in about 5 hours, how are people using other things that draw a boatload more current? Never mind all the people who successfully use their CPAPs?
I also have seen you post that graph, and I find it interesting. It would be nice if they spread out the x axis more, so I could see differences between 0 and 20 hours better, and also if they started with a higher SOC on the battery, say somewhere between 35-50%, where I would bet a lot of RVers take their bats down to before topping off.
Also, as the curve is so steep the first few hours or so, does it matter so much whether my charger is 20 amps, instead of 40 or 50, or even 70? Does the 20 amp setting on my Schumacher charger mean that 20 amps is the max, or does it go higher at the start, then settle down at 20, then gradually to trickle as it gets closer to full?
I have read hundreds of posts of most people bringing their bats from 50 to 90 percent with their gens, with run times approx 3 hrs a day. Your chart says that is improbable, if not impossible with even a 55 amp charger/converter.
Something's not adding up. What am I not seeing?
