Camper_Jeff_&_Kelli wrote:
pianotuna wrote:
Camper_Jeff_&_Kelli,
Most RV absorption fridges have a 2/3 duty cycle. I.E. in one hour 40 minutes on and 20 minutes off. I did a "back yard" experiment on this about a dozen years ago. My fridge does draw 325 watts.
I just read a post in rv.net from 2018 in the vans and in Florida 90 degrees. The author had a duty cycle of 65% but when he switched the fridge over to 12 volt, it performed much better.
That is the exact opposite of what I observed and measured. IIRC draw was 34 amps on 12 volt and about 37 amps on 120 volt from the battery bank, but temperature and duty cycle were dramatically different.
I did try running the 12 volt side when using shore power--and then it worked well. The testing was carried out at about 65 F (18 c)
Duty cycle remained at 2/3 for 120 volt or 12 volt (powered by 120 volt shore power) and on 12 volt *only* dc, duty cycle was nearly 100% (or 3/3)
The test was done with an 875 amp-hour Marine battery bank.
It was done because I wanted to see if I could cool down the fridge using 12 volt DC while the RV was still in storage. I concluded that it was not viable because the fridge did NOT cool well on 12 volt, and to stay above 50% state of charge the fridge could not be on for more than about 8 hours.
