Forum Discussion
Almot
Oct 14, 2014Explorer III
What we are missing here, is that when you live off the battery, you should measure DC draw out of the battery in AH. Not AC draw to the fridge. Very few users of 120V fridges actually did this - if any. An appropriate device for this would be a battery monitor - or amps on display of solar controller when fridge cycles on, less informative but OK.
Stipulated inverter efficiency, killa-gilla-watt, this doesn't tell much. There are DC-AC conversion losses, inverter standby, inverter idling (that you can't completely eliminate when you have semi-permanently running fridge), and whole bunch of parasitic currents of trailer before you even start to do anything there. I won't be surprised to see 15-18 AH for all this, - and then you have actual useful loads. Show me AH out, for the 24 hours period, at 85F. With 10cf fridge and a single bulb on the ceiling.
More mass means more energy to remove the heat to the outside. How "smaller" is your dorm fridge? 80W is roughly a 42 AH "AC equivalent", deducted from 80W*6hrs AC. Don't ask me what 42 AH AC means :)
Stipulated inverter efficiency, killa-gilla-watt, this doesn't tell much. There are DC-AC conversion losses, inverter standby, inverter idling (that you can't completely eliminate when you have semi-permanently running fridge), and whole bunch of parasitic currents of trailer before you even start to do anything there. I won't be surprised to see 15-18 AH for all this, - and then you have actual useful loads. Show me AH out, for the 24 hours period, at 85F. With 10cf fridge and a single bulb on the ceiling.
westend wrote:
My smaller dorm fridge draws 80W when running. The duty cycle is around 25% in summer weather (80f-90f ambient). The somewhat larger fridges can be more efficient because of better insulation and containing more mass,
More mass means more energy to remove the heat to the outside. How "smaller" is your dorm fridge? 80W is roughly a 42 AH "AC equivalent", deducted from 80W*6hrs AC. Don't ask me what 42 AH AC means :)
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