Power hungry fridge...

[loisjop]

Originally Posted by 94-Newmar

A couple of responses above are confusing AC consumption versus DC consumption. The OP is seeing 13-18amps of 12 volt DC being used/consumed while inverting which would correlate roughly to 1-1/4 to 1-1/2 amps (150-180 watts) of 120v AC. As we've all discussed numerous times and again mentioned by Nothermark above, the inversion process is absolutely and completely horrible in efficiency due to the approx 10:1 overhead of inverting AC power from a 12v DC source.

If you're using a pretty common setup of 4-6volt DC GC2 type batteries setup in a combination parallel/series configuration you will have roughly 440 amp hours of energy available to you IF they're fully charged AND in perfect working condition. Consuming a constant 10amps of 12volt DC power from that battery configuration will give you roughly 44 hours of usage before the batteries are completely depleted if you're not putting any charge back into them ala boondocking. Keep in mind, most inverters are configured by default to stop inverting when battery voltage reaches 11.5 volts or so... Therefore, you'll never see 44 hours of consumption before the entire thing shuts down. Real life numbers will allow you around 30 hours (a day and a quarter) before the entire setup becomes unusable.

The newer way that these manufacturers list their consumption ratings is nothing more than a complete obfuscation of the actual usage. They cannot take into consideration how full the refrigerator is loaded. Was it loaded with room temp foods? How often is it loaded with room temp foods? How often is the door opening and closing? What about the ambient relative humidity and temperature? What about the ventilation being provided? How in the world can you possibly figure kwh/yr based upon so many different factors that will obviously vary from owner to owner? You can't. You can only make an assumption based upon a group of averages. Bullcaca.

He doesn't say anything about checking it on 12 volts. He says it pulls 13 amps all the time and will drain his batteries, but doesn't say he checks it on 12 volts. He may be but doesn't specify. Noel

[94-Newmar]

Originally Posted by loisjop

He doesn't say anything about checking it on 12 volts. He says it pulls 13 amps all the time and will drain his batteries, but doesn't say he checks it on 12 volts. He may be but doesn't specify. Noel

Of course he does.. how else would he get a huge amp draw reading of 13amps? It certainly wasn't on the 120v AC side of things! :-)

[Dr4Film]

Originally Posted by loisjop

He doesn't say anything about checking it on 12 volts. He says it pulls 13 amps all the time and will drain his batteries, but doesn't say he checks it on 12 volts. He may be but doesn't specify. Noel

Originally Posted by 94-Newmar

Of course he does.. how else would he get a huge amp draw reading of 13 amps? It certainly wasn't on the 120v AC side of things! :-)

You are absolutely correct and I have to apologize as I had missed that when I posted.

In reality, his fridge is pulling 1.3 - 1.8 amps @ 120 VAC when you do the conversion. Although those numbers are on the high side compared to my Samsung there are not off the wall and should not be the complete reason why his 6 - 6 VDC Battery bank is only lasting 3-4 hours before the AGS kicks on the generator.

With that specific battery bank he should have about 340 AH's of use BEFORE the AGS kicks on with healthy batteries @ 50% SOC. At 15 amps/hour that well over 24 hours of use.

Something stinks in Denmark!

Dr4Film ----- Richard

[nothermark]

FWIW Inverters are not that big an issue in efficiency. True, there is a loss in conversion. The real issue though is the basic power equation. Power = Volts x Amps. If you want to change the voltage and keep the same power you also get a commensurate change in current. When one goes down the other goes up. With today's electronic converters that will be a bigger issue than conversion loss.

I agree that there is a problem with how the refrigerators are specified with power consumption alone. If someone who is collecting data on these could also collect currents it would help figure out consumption issues. As far as I know there are 3 states of interest. Idling with the compressor off should be lowest. Then there is the compressor run current. Highest would be with the compressor on and the defrost cycle running as that includes some strip heaters. If the compressor cycles during defrost that might also be of interest. That would let folks make sense of the numbers they see.