Got my solar sorted a few weeks ago and thought I’d do a bit of testing with the fridge to see if my solar will support the fridge permanently running without any additional help. I’ve now gone down a rabbit hole trying to determine if my fridge is faulty and would appreciate any views on this
@Dellmassive or anyone else who has experience in this area.
Quick background. Was doing a very long run with a couple of friends a few weeks ago so popped some food, water etc in the fridge in the van so when we finished we had something to eat and drink. It was a cool day with intermittent sunshine. When we got to the van the food was OK but the drinks didn’t seem particularly cold (fridge was set to 3C). That is what started me down the rabbit hole.
I’ll skip all the things I’ve done in between times and cut to the chase. I’ve popped a couple of temp sensors in the fridge and one next to the outside of the fridge in the van. I’ve now set the fridge to -2C which i reckon is giving an average temp of 2-3C in the main compartment. I seem to have a difference of 4-5C between what the fridge is set to and the actual temp in the fridge. The sensor in the main compartment is placed in the centre at the bottom (coldest place and where i believe the thermistor is located). I have another sensor in the small compartment, more on that one later. During the day, the fridge seems to do it’s thing, compressor turns on and off and temp is controlled, the average temp does seem to drop as little over the day. At night when the outside temp is low, the fridge shuts down and eventually turns on again. This morning I took the picture below. Sensor shows 3.69C, fridge thinks it is -1C, so it doesn’t turn on. It does eventually as the outside temp rises. The delta between the fridge setting and the actual temp seems to vary as the ambient temp rises. as ambient rises, the delta reduces. Overnight, as ambient drops, the delta is larger. Picture of 24HR temp trace below.
I can’t decide if the thermistor is duff or not. On the surface it works but I shouldn’t need to have the fridge set to -2C for it to actually be 3C. I’m also puzzled by why the temp overnight seems to be a little higher than the temp at which the compressor kicks in during the day (Why doesn’t it start up as it does during the day)
In doing this testing I have also noticed the smaller compartment can be 7C or more higher than the main compartment. I was very surprised by this. There is no direct cooling in that compartment so I i expected it to be higher, just not than much......
On the positive side, the solar seems to be performing very well, Leisure battery voltage has not been below 12.3V or so since the fridge was connected, Starter battery has also been higher than normal as solar is charging that too. I’ve also watched the current output switch up as the compressor on the fridge kicked in so the full current draw on the fridge was coming from solar. Picture below this morning where solar is charging starter battery (5.36A) and trickle charging leisure (1.13A)
Apparently the thermistors in WAECO/DOMETIC fridges off this type are known weak spots. I have watched a few youtube videos of Aussies dismantling their fridges and cutting up the insulation to get to the thermistor to change it. I won’t be doing that as mine is still under warranty.
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