I am trying to estimate how long I can run a device on battery power.
The device is my CPAP machine that draws .7A 120 volts. I am running it thru a DC to AC inverter that says it produces 120 volt AC 60 hrz 110 watts cont, 140 watt peak for an input of 10 to 16 volts DC.

The battery is old, so I don't know if the ratings are even valid, but they are 935 CA at 32 degrees F, and 750 CCA at zero degrees F.

I have been running it for the last hour and here are my readings:
elapsed time battery voltage
0.0 minutes .... 12.92
0.25 " .. ... ......... 12.78
0.50 " .. ... ......... 12.73
1.0 .. .... .......... 12.70
2 ...... .... ......... 12.69
4 ......... ......... 12.68
8 ............. .... 12.68
15 minutes ..... 12.65
30 minutes .... 12.62
60 minutes .... 12.57
120 minutes......... 12.46


Can someone estimate the time before the voltage drops to 10.0 which is the minimum needed by the converter?
If I run it for 8 hours, will it recover for another nite?

__________________
1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

Need better data on the battery what is the model number?

If it helps, the model # is 65-750.

__________________
1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

http://www.dcacpowerinverters.com/faq.htm#22


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