ouR escaPOD mods

Okay. I understand that method, but it isn't going to happen. I'm not going to sit out there with a stopwatch. I was looking for a solution that could record without me being there baby-sitting it.

I'm already happy with it. Given that we made the trip with the cooler and experienced similar power draw, I think we will do okay with the CRX-1100. During ARRL Field Day I observed the meter but did not record use then. That was before I added extra insulation, which I expect will really help with the power use. I have an AC-DC clamp-on meter. However, it would not be suitable for observing long term because it would be detecting spot use, not tracking or recording use.

That works out to 30 amphours per day for a 20C delta T (25 ambient vs 5 in the fridge). Sounds about right.

For a hot conditions 40C delta T (40C vs 0 in the fridge/freezer) that would double to 60 amphours, assuming the COP of the compressor stays the same. But it doesn't. It drops to about 1.5 from 2.0. So now we're at about 80 amphours per day (2/1.5*60). And we're still not opening the fridge door or taki g things in and out.

Reality is almost never what the specs say. It's a lot like the fully loaded trailer weight vs the manufacturer's empty weight specs.




Don't misunderstand me. I really like the Danfoss BD compressor fridges. It's just that their advantage over absorption units (being able to maintain a cold fridge in hot conditions) doesn't come for free. You have to have an energy source for them. If you really pushed a Danfoss BD35 fridge to it's limits and it ran continuously, you'd need about 150 AH/d for it. That's what the African village chief did with his warm beer beer in my vaccine fridge....

Around 1990-ish but the bd35 compressors are essentially the same units, as are their COPs. In fact Danfoss markets and is proud that they have been around for over 35 years. Demonstrates their reliability.

The ASHRAE testing published by Danfoss was done with an ambient of 32C or 90F, which gives a COP of about 1.9 for an evaporator temp of -5C. Compressor only not including any fans.

90F is low, I used to test at 40C or 104F ambient, at which point the COP was around 1.5. The current Danfoss spec sheet is dated 2004 btw.

My basis is test results for Danfoss vaccine fridges that I worked on and installed in Africa and Latin America. Danfoss has made pretty much the same compressor for going on 35 years now.

Also, you can base it on the COP numbers from the Danfoss spec sheets. Those are pretty accurate. You have to make assumptions about the fridge box insulation performance but that's not too difficult.

Besides, in the real world ppl put warm things in their fridges to cool them down. That's just being human. That uses a lot of energy which the absorption fridges can't handle but the compressor fridges can (up to a point). I learned that the first time the chief in one of the African villages I installed a vaccine fridge in immediately commandeered it to cool down his beer bottles. All my energy calcs went right out the window. I would probably have needed a kw of solar to make him happy.