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No, they're not. they're very efficient (> 95%)theaftermath wrote: ↑Sat Nov 03, 2018 6:55 pmI must be missing something. The DC-DC converters for these are terribly inefficient aren't they? Input is 12v/24v 13A/6.5A with an output of 24v 3.75A!!
Ah is not the same as wh: power (watts) is current (amps) multiplied by voltage, amps only measures current.theaftermath wrote: ↑Sun Nov 04, 2018 3:50 pmI guess the reason I'm a bit stumped is because hooking this up to a Killawatt meter it shows about 300wh for about 8hrs of use with humidity and tube turned on but it won't last 6 hours using this converter with 70ah battery? Is the converter going bad?
I do understand they are different, just showing my results. When plugged into AC the results showed that the machine would easily run off of that same 70ah setup that wouldn't run for 6 hours with the DC-DC converter.Snoregone Conclusion wrote: ↑Sun Nov 04, 2018 4:10 pmAh is not the same as wh: power (watts) is current (amps) multiplied by voltage, amps only measures current.theaftermath wrote: ↑Sun Nov 04, 2018 3:50 pmI guess the reason I'm a bit stumped is because hooking this up to a Killawatt meter it shows about 300wh for about 8hrs of use with humidity and tube turned on but it won't last 6 hours using this converter with 70ah battery? Is the converter going bad?
I did see this and it suggests a 45ah battery for the settings used on the machine but from the kw meter results when plugged into AC compared to not being able to get a full night out of a 70ah battery when using their DC converter something is off?prodigyplace wrote: ↑Sun Nov 04, 2018 4:15 pmHere is the Resmed battery guide that assumes you are using their inverter to convert 12 V DC to 24 V DC.
https://www.resmed.com/us/dam/documents ... lo_eng.pdf
The amount of current / power used depends on a number of factors. Mask pressure, humidity level, and use of heated hose can all affect how long a battery will last.
The settings of the machine were the same but I don't know about surrounding air humidity or temperature differences.prodigyplace wrote: ↑Sun Nov 04, 2018 4:15 pmHere is the Resmed battery guide that assumes you are using their inverter to convert 12 V DC to 24 V DC.
https://www.resmed.com/us/dam/documents ... lo_eng.pdf
The amount of current / power used depends on a number of factors. Mask pressure, humidity level, and use of heated hose can all affect how long a battery will last.
More likely your battery is bad,theaftermath wrote: ↑Sun Nov 04, 2018 3:50 pmI guess the reason I'm a bit stumped is because hooking this up to a Killawatt meter it shows about 300wh for about 8hrs of use with humidity and tube turned on but it won't last 6 hours using this converter with 70ah battery? Is the converter going bad?
I agree - a 70ah battery should have about 840 watt-hours. The testing with my Philips 560 was around 20ah with moderate humidity/hose settiings. The ResMed is a bit less efficient.palerider wrote: ↑Sun Nov 04, 2018 6:33 pmMore likely your battery is bad,theaftermath wrote: ↑Sun Nov 04, 2018 3:50 pmI guess the reason I'm a bit stumped is because hooking this up to a Killawatt meter it shows about 300wh for about 8hrs of use with humidity and tube turned on but it won't last 6 hours using this converter with 70ah battery? Is the converter going bad?
Five nights might be a stretch - that's 7ah a night with no reserve.