12v Refrigeration - What size do you use?

[fishboat]

Ever been to Big Island Lake in Schoolcraft County? It is a small version of Sylvania. Very quiet and remote. Northwest of Manistique.

When I had the fridge shroud off one of the things I wanted to investigate was a way to hard wire the "de-stratify" fan (12v version) to the 12v wiring inside so I wouldn't have to mess with batteries of any kind. In the Alpicool finding a spot to do that was not hard. In the photo you can see the wiring block. The top two terminals are the hot and neutral terms. The fridge's condenser fan is just a 120mm case fan, 12v. It runs only when the fridge is running, so, I think hooking up the little fan to these two terms would work to de-stratify the fridge. The biggest challenge (more a fear of screwing up a new fridge) is how/where to drill a small access hole to run the wire. I once witnessed someone drilling into a home fridge to put a hasp and lock on the door of the fridge. He happened to drill right through a coolant line effectively making a brand new fridge into a non-working one. So, If I do this I will do it with some forethought.

Sylvania..yah..nice place. We were there in mid-August and had the place (our loop) pretty much to ourselves. There were only about a half dozen campers in the whole place.

Haven't been to Big Island. I know of it, but just haven't penciled it in for a trip..yet.

Tapping into the internal wiring sounds perfect. I'd guess the circuitry upstream from the 120mm fan was designed for the load it sees downstream, but an extra 25mm fan(100ma or less) wouldn't matter. I'd be nervous about drilling the access hole too. Those fridges pack a lot of stuff into a very small space..random holes could be costly.

[fishboat]

Got back last night from a 4.5 day trip. The fridge-PVC pipe fan worked great. I loaded the fridge the day before we left. Set point was 36. The next morning the top of the fridge where the temp sensor was showed 51 degrees(bottom was at the set point, or below**). I kicked on the pipe-fan and the top of the fridge-contents cooled down to 41 degrees while we were driving to our destination. I had the pvc-fan running off and on for 5-6 hours at a time throughout the trip..the top of the fridge-contents stayed within 5 degrees of the setpoint..worked nice. Never needed to recharge the power bank.

Overall, I think my trailer power usage increased a bit as a result of the (independently-powered) pvc-fridge fan. I don't know-exactly, as I've previously run a fridge setpoint of 34F. On this trip I ran a 36F setpoint and used about the same amount of power as previous trips..189w/day over the whole trip versus the previous trip of 183w/day. Ambient temps over both trips was abut the same..low-mid 70s during the day 55-60 at night, campsite was 100% shaded. Using a bit more trailer power to run the fridge makes sense as the fridge is now cooling a larger (loaded) volume than it did previously.

As far as power consumption with running the fridge..lots of juice left after 4.5 days with the batts at 12.45v when we rolled into the driveway at home. Average amps/hour usage was 0.63 for the fridge(could have theoretically gone 7.6 days at the rate before needing to recharge @50% battery drain). Previous trip was 0.61A/hr.

**The 50-ish degrees on top of the loaded fridge while camping has been typical on previous trips & is why I made-installed the 5V vertical pvc pipe fan..problem solved..it seems.

[TimC]

Good report Fish. I too just returned from a four day trip to Michigan Irishfest and, though I didn't record data my solar recharged the batteries fully each day despite having a couple of days with clouds. I didn't install my fan/pipe yet. Dragging my feet on a USB pack. I've got one, but, as I noted previously the fan doesn't pull enough current to keep the pack from shutting off.

One thing I did discover is when leaving the fridge outside in the rain (yeah, not a great idea) don't just pop the door open without removing the sitting water on top. It just rolls off right into the "warm" compartment soaking everything in there. Kinda like using ice in a cooler with water everywhere

Anyway, the fridge is a great addition to the TD. I didn't have to think about ice once during the trip. It's actually still running in the TD as I got home very late last night. Another plus for the fridge...