(03-31-2018, 10:04 PM)OMyMyOHellYes Wrote:(03-31-2018, 04:35 PM)Ron AKA Wrote:(03-31-2018, 03:52 PM)srlevine1 Wrote: If you are going mobile, the inverter is a waste of energy, you need the ResMed DC-DC Converter which bumps the 12v battery output to the 24v needed to power the S10.
Do you have any data on the total loss of an inverter and AC to DC adapter compared to a ResMed 12 volt DC to 24 volt DC converter?
You can compare battery requirements for various units using the DC-AC perverter or the DC-DC converter.... Note the brand of CPAP I have standardized on, except for travel, when I use an old model S-8 which still uses straight 12 V straight off of a battery (reverse polarity plug rules apply).
Good suggestion. I was aware of the ResMed Battery Guide, but didn't think to compare their inverter option to the DC to DC converter. When I compared the S9 current draw at 20 cm and no humidity or heating I got 1.41 amps at 12 volts for the inverter, and 1.00 amps for the voltage converter. That would suggest a 29% reduction in power, just as jaswilliams posted earlier. I think I will bite the bullet and buy a voltage converter for both myself and my wife. She averages about 12 cm and I should be lower at 8 cm. That should result in an average current draw of .65 and .46 respectively, for a total of about 1.1 amps. That is not far off what she is using alone with an inverter set up. Should work with my existing size of solar panel too. Good news, other than for the price of the converters.
Yes, having a 12 volt CPAP would be great. Solves a lot of problems.