Rotary inverter driven camping fridge compressor

For those who need a refresher read post 18859

My understanding is as follows:

The compressors used by the particular Manufacturer of portable fridges, were first made by Senlin Electrical Appliance compressor plant in China, which was a joint venture between Mitsubishi and Shanghai Senlin.

I beleive the Mitsubishi compressor Model RR120 is the Senlin model XAZ309.

In standard form the compressor has a nominal capacity of 99watts refrigeration at –23.3 C suction temperature, (a industry standard rating point) running on 240 Vac 50 hertz. This capacity also equates to what the manufacurer stated their compressor does on 50hz.

The compressor has a nominal input (power consumption) of .085 watts.

These compressors used in said fridges are driven by a 12vdc – 240vac inverter, and, the speed of the compressor motor is increased by altering the frequency output of the inverter. The output frequency to the compressor is around 60 hertz.

This speed increase also increases its capacity and this can be calculated easily. The compressor performance then works out to be approx 119 watts of refrigeration. ie 50hz divided 60hz = .83…. & therefore 99 divided by .83 = 119 watts refrigeration. Whilst claiming input watts of 98.4.

For your reference only: I cannot understand why the watts input
have’nt gone higher, to say around 100, but I will give them the benefit of the doubt. The manufacturers data for a the XAZ309 compressor operating on 60hz gives 123watts refrigeration duty & has input watts of 100. Minor but a slight increase on their data.

To arrive at amps on 12v they used the formulae: amps = watts divided by volts ie 98.4 divided by 12vdc = 8.2 amps….so where are the inverter losses I ask?

I re-iterate, they state the following on their web site:
“The following wattage consumption (input), wattage produced (output) and co-efficient factors (co-ef) are derived from each compressor manufacturers specification”. Note the word DERIVED! meaning calculated….but they forgot to include something…eh?

Then we have the other associated in-efficiencies due to the greatly oversized compressor to take into account.