amp/hrs for dometic frig

[Virgil Jones]

I appreciate everyone's replies to my posts.
I am working on an amp/hour usage list to size my solar system batteries.  I will have 400watts on the roof with thoughts of  more ground deployed is necessary.  I am trying to size the system to stay at 75-80% Volts or higher.  
I have been unable to find the actual amp/hr demands of the two Dometic portable refrigerators I'm looking at...CFX-65 and CFX-50.  Does anyone have experience with these, or a site that actually gives amp/hr statistics?  I could not find it on the Dometic site.
Thank, Virgil

 

[Optimistic Paranoid]

There are two figures available for the CFX50.  It uses 7.8 amps while running.  And it's annual energy consumption is 66kwh per year.

1:  So it uses 7.8 amp hours every hour it runs.  Times 24 hrs and you've got 187 ah a day.

Of course it doesn't run continuously.  How much it runs depends on the ambient temperature, how often you open it, etc.  If it runs 10% of the time, it would use 18ah per day.

10% = 18ah
20% = 36ah
30% = 54ah
40% = 72ah

etc.

2:  It uses 66 kwh per year.  A kwh is 1000 watt hours, so 66000 watt hours.  Divided by 365 days and you get 180 watt hours per day.  The conversion formula is AH = WH/Volts.  So 180 whs divided by 12 volts = 15 ah per day, on average.

That's the theory.  It will be interesting to see if anyone here has some hard numbers based on experience, and how well such numbers might match the theory

 

[Virgil Jones]

There are two figures available for the CFX50.  It uses 7.8 amps while running.  And it's annual energy consumption is 66kwh per year.

1:  So it uses 7.8 amp hours every hour it runs.  Times 24 hrs and you've got 187 ah a day.

Of course it doesn't run continuously.  How much it runs depends on the ambient temperature, how often you open it, etc.  If it runs 10% of the time, it would use 18ah per day.

10% = 18ah
20% = 36ah
30% = 54ah
40% = 72ah

etc.

2:  It uses 66 kwh per year.  A kwh is 1000 watt hours, so 66000 watt hours.  Divided by 365 days and you get 180 watt hours per day.  The conversion formula is AH = WH/Volts.  So 180 whs divided by 12 volts = 15 ah per day, on average.

That's the theory.  It will be interesting to see if anyone here has some hard numbers based on experience, and how well such numbers might match the 

Thanks.  That gives me starting point for that model.  Where did you find the 7.8 amp/hours?

 

[Optimistic Paranoid]

Thanks.  That gives me starting point for that model.  Where did you find the 7.8 amp/hours?

Page 41

http://dometic3frontend.qbank.se/episerver/4e4869c12089468fa69ceca248253b17.pdf

 

[SternWake]

Page 41

http://dometic3frontend.qbank.se/episerver/4e4869c12089468fa69ceca248253b17.pdf

Weird that in English is says 7 amps and other languages it says 7.8 amps

These have the newish  Waeco compressor which visually appears similar to the vererable danfossBD35f

The danfoss is variable speed 2000 to 3500 rpm, ~2.5 to 6.5 amps

I'll guess the 7 amps is the figure during initial cool down  when compressor runs at max speed.  I would not expect it to run at full speed every time it cycles on.

In 75f ambient temperatures, Used as a refer, not freezer,  with a sane amount of brief lid openings, i would estimate 65 liter model 26 to 34 AH consumed in a 24 hour period and 20 to 26 for the 50 liter model.

I would not want 7 amps passing through a ciggy plug.

The ciggy plug is always the weak link.  

Danfoss's tech page lists minimum wire sizes much thicker than one would expect for the current drawn, and that the portables that come with Danfoss's come with ciggy plugs and 16 awg wiring, well that should be considered an electrical  felony.

http://files.danfoss.com/TechnicalInfo/Dila/06/bd35-50f_electronic_unit_ac-dc_04-2009_ei100g402.pdf

Since this Waeco compressor can draw an even higher amperage, lets call the ciggy plug on these a higher class of electrical felony.

I'd figure out a way to run 10 AWG right from plug on fridge to house battery fuseblock.

No point in wasting battery power heating up thin too thin of copper wiring or a ****** ciggy plug and receptacle.

Also the voltage drop on the thin wiring can have the unit shut down thinking it is protecting the battery, when the battery is in no danger of overdepletion, possible risking the safety of food inside.

So a ciggy plug could equal a fun run with some food poisioning, spewing from both ends.

 

[Spaceman Spiff]

That's the theory.  It will be interesting to see if anyone here has some hard numbers based on experience, and how well such numbers might match the theory

I have a Norcold DE-251D with 3" polyiso around top, bottom, and sides, 36 sq.in. of forced ventilation around condenser.  It draws 4.5 amps on startup tapering to 3 amps.  I find 30% duty cycle to be a good number to use for 70º - 80ºF (inside camper) temperatures.  For temps above 90ºF, duty cycle goes to 50% or more.

 -- Spiff