Freezer/Refrigerators, portable

Patrick, We are currently running two grp31 deep cycles for the house and that should be enough juice to do a lot with a small freezer. I don't think your unit will use significantly more than ours based on its specs. We have done one type of trip so far out east (lake Roosevelt) where we leave the boat sitting more than normal (fishing from friends day boats), only running our boat for 1-2 hours every other day in temps that are higher than out on the salt in the northwest. That trip could possibly push our battery limits and would be the one where a temporarily rigged 50w solar panel could be the solution. I think for the rest of our trips, we will move enough (outboard charging of about 10amps average) to keep us topped up and not worry about our little ice factory. I will keep posting here as I test and learn more.

Greg
 
I have a 50 liter compressor type cooler with the Danfoss BD35 compressor (Dometic/Waeco CF-50). I bought it with the C-Dory in mind, but have lots of data from my RV, where I have been running it continuously since last June, with the temperature set at 31ºF. I have no additional insulation (and the lid is pretty thin). I do sometimes throw a pillow on top of the lid at night.

Ambient temps have ranged from about 90ºF day/50º night; to 55ºF day, 40ºF night. The cooler is never in direct sun, but the RV is more or less at ambient temperature much of the time (don't run heat at night; sometimes heat the room up to around 60ºF in the evening or morning).

I'd say I'm averaging around 25-35 amp hours per day being used by the refrigerator. 25 being more typical, but 35 when it's really hot. This is not 100% scientific, but is based on my total usage, some of which is days when I also charge a few other things (but I know about what those things draw and subtract them), and some of which is days when only the refrigerator runs, plus an LED light in the evening (that makes it easy).

I originally had planned to do the "freeze and rotate" plan with my Coleman Ultimate Extreme cooler, but then this CF-50 came up on a good sale and I decided to go for it. (I might have gotten a smaller compressor unit otherwise.) I guess I could still do that but on a larger scale - by using the CF-50 as a pure freezer and my 58 quart cooler as a cooler with rotated ice packs from the 50 - but for now just the CF-50 is working well (albeit that means I basically only have a refrigerator). It is a bit large to put inside the 22 though (could be done with mods).

Anyway, just figured these amp draws might help someone; even though there are tons of variables. Although anyone can look up what the compressor draws, that's not the full picture since they don't typically run on a 100% duty cycle.
 
Patrick the ARB is slightly more efficient than the Dometic 50. Pat Anderson had a ARB, and I believe that his 100 watt solar panel was just not quite enough at Powell. You have different ambient conditions--both the time of year, and in the PNW climate. So there may be more draw in the summer.

We find that 30 amp hours is a good average for our dometics over a 24 hour period. We use one as a freezer and the other as a refrigerator. We use about 30 amps each 12 hours, and put that back into the group 31 AGM battery over 2 hours, using a 30 amp dedicated charger. (We use as an end point when the charger has dropped to 3 amps, and the charging voltage is getting to the mid 13 range--close to float stage, well out of bulk and absorption phases.

If you try and use the charger which comes with the boats, it is difficult to catch up. I have also been told that running those charges at max capacity shortens their life span. I have had a number of them give out on me. I solved that with a 20 amp 3 bank MasterVolt upgrade. I also highly recommend a dedicated meter to monitor amps used and battery voltage, like the Victron 600 or 700/702.
I am experimenting with a small volt/amp/cummulative amp meter I got off Amazon for about $19 which I will just use on the dedicated freezer/refer battery.
(Bayite 6.5 - 100 V DC, 0-100 Amp DC. (not water proof, and requires manual reset). But cheap--and has good feedback.

There are several other threads on these type of refers, the pitfalls, and issues keeping them charged.

http://www.c-brats.com/viewtopic.php?t=22018

http://www.c-brats.com/viewtopic.php?t=23082

As far as charing with the engine--it depends on the size of alternator, available amps, other draws, temp etc. We have a Honda 90, which only puts out 17 amps--and not all of that is available.

Greg, there are lots of variables with how long the ice will last--how often you open the cooler, if you take things out and put back in, the ambient temperature, If you keep a damp towel over the lid of the cooler, etc. We found out Coleman extreme to be good coolers, but Powell is not a great place to test for ice, since the ice is very granular, probably kept at just below 30 degrees, and a high ambient temp. We also have and "outer Banks" (similar to Yeti), and found it holds cold/ice better than the Coleman--by just a little, but it is a bigger chest, so we used it--but finally went to the two compressor driven units for a long time on the hot lake.
 
Greg-Thank you, yes, I need to size for a couple of grp31s it looks like.

Bob-Thank you for your input, as well. Lots to think about. I am doing a small solar power demonstration in my 5th grade classroom and it is pretty neat. The kids are learning a lot. I bought the same amp/volt meter and it came with a big shunt which is not mounted on anything, no plastic/phenolic base. I am puzzled on what to do. I have read that some people just epoxy a piece of plexglass so the bolts are recessed. What did you do?


(I am experimenting with a small volt/amp/cummulative amp meter I got off Amazon for about $19 which I will just use on the dedicated freezer/refer battery.
(Bayite 6.5 - 100 V DC, 0-100 Amp DC. (not water proof, and requires manual reset).
 
Patrick the vast majority of these amp meters have a separate shunt. I am just mounting my shunt on the side of the battery box. I made a pigtail, from the negative battery terminal to the non load side of the shunt. Since it is on the negative side, there is no chance of arcing with contact. I will probably make a plastic cover for it. Sort of on the experimental stage for this trip. I have about 20 feet of 5 wire cable, and will put the meter near the helm. Probably secure it with velcro--at least for now.
 
More testing and some stabilizing of the results.

Our Engel MD14f has settings 1-5

Setting 3 is supposed to hold 14 degrees F for reference. The numbers below are with the unit containing 1/3 load of thawed water and 2/3 load of frozen water to simulate how we plan to use it. The temps at the time averaged in the 50s which I had to run a heater to achieve during the winter season. I used a victron meter for amp draw numbers.

On setting 3 we can make ice and keep ice easily with an average draw of 1.5amps per hour for a total of 36AH for a 24 hour period.

On setting 2.5 we can make ice within a day and keep ice easily with an average draw of 1.23amps per hour and a total of just under 30AH for a 24 hour period.

On setting 2 we can keep ice but not make it within a day using an average draw of .9amps per hour or a daily total of about 22AH

I am happy with the energy use so far and plan to due some different testing for longer periods soon.

Greg
 
For testing the ambient temperature, sun exposure are important, and should be noted.

Dry Ice has been available at Powell, and many other places. It is limited in duration, although with well sealed, insulted containers, and once a day access we have kept food for 12 days. (Transpac race--temp in the cabin from 65 nights at the start to 85 days at the finish.)
 
We opted not to use shore power at Friday Harbor last week so we could test the solar/freezer combinations

Thursday midday started at 95% SOC (state of charge)-Sunday midday ending at 64% SOC with a decrease in state of charge averaging 10% per day

We ran the Freezer at setting 2.5 and swapped 6 ice bottles each day (3 per cooler) which based on our testing should have consumed nearly 30AH per day.

We also ran the heater for 2+ hours per day which should have consumed roughly 3AH plus charged four devices each day consuming roughly 4AH per day. We did use some lighting but that was minimal and all LED.

Our victron monitor displays the State of Charge and that is based on a total adjusted bank size of 200AH.

Our true bank size is 220AH but knowing the true capacity diminishes slowly over time, and wanting the ability to safely use the 50% mark as our use limit, I use the reduced capacity of 200AH to keep a safe margin.

We should have consumed about 37AH per day for a total of 111AH over the 72 hour non-charging period. That much consumption (ignoring P's law for now) should have brought us down below the 50% SOC mark but we stayed up in the mid 60s.

IF we lost 10% each 24 hours, and were using 37AH in that timeframe and based on the 200AH total bank reference, we should have ended at about 130AH remaining at the 64% SOC charge mark on the last day. But, our net use was about 70AH leaving at gap of 41AH between the total power consumed, and the power remaining.

So, the solar generated roughly 41AH in 72hours of mixed clouds and sun which is over 13AH per day and close to what I expected. This gives us a realistic 5 continuous days of boat use (freezer, heat, devices, lighting) relying on solar alone for power. We don't ever sit that long without moving by motor so our power needs have been met and ice will no longer be a limiting factor for Ari.

I know this is all a bit rough but we were pretty busy with the gathering so I roughed it this time. I will track more details on future trips.

Greg
 
Greg,l
Good experiment. What was the SOC Sunday AM when you first got up?

I assume that your goal is to never drop below the 50% SOC.

Thanks.
 
It was 63.4 when we woke up before we ran the heat for a while Sunday, but then came up a little (thanks solar) by the time mid-day arrived and we motored out. We never plan to go below 50% and when our unit reads 50%, it should actually be closer to 55-60 in reality giving us a little buffer.

Greg
 
Those are some impressive numbers Greg. That really gives one piece of mind when you don't have to be tied to ice/shore power.

We'll see what happens with our unit. With battery charger off, I also just ran the ARB freezer/refrigerator on battery and had it set to 20 F. For the same time period, without a Victron battery monitor, we started with 13.7 volts on the two flooded group 31 in parallel with 230 AH capacity. Sunday I measured 13.1 volts. We used very little 12 v lighting. It looks like a Victron is in our future.

Thanks for your report.
 
Salmon Fisher, Since you showed voltages over the resting state of charge, you must have some charger on--presumably the solar panels. This voltage does not equate in any way with state of charge. For Voltage to have meaning, it has to be at a steady state, with no charger, or draw (i.e. when the refer is off).

The Vectron, Link or the much cheaper ($18.75) Volt/amp/watt hr meter will measure in some form the amount of current/SOC--either by steady state voltage or amps/ watt hours.

This is not water proof, and must be physically manually reset. I have a Link for the main house system, and use the cheaper Baylite meter for just the battery dedicated to the freezer and fridge (2 chests). More for experiments
 
Thanks for that link Bob, I just ordered one of those simple meters and will put it on the incoming Solar feed for more specific readings while the victron is busy with other loads.

Greg
 
I just had a Victron installed. I'm very happy with it.

I think the most useful part of it is the shunt. It measures ALL the amp-hours both in and out of the battery bank. There is no dependence on projecting the SOC based on a voltage reading since instead one is always measuring the actual electron flow in or out of the battery. I find it satisfying to know, for example, that last night 25.6 Amp-hours flowed out of the battery; so since my house bank is 120 amp-hours, I know just where I stand (the Victron has a display that does this SOC calculation for you, but I prefer just knowing the actual amp-hours I've used, or conversely, the amp-hours I've charged).

Thataway, I looked at that $19 meter link. Certainly is cheaper, but it seems to have a fatal flaw; to wit, if the current reverses (that is, even a short burst of charge such as when you briefly start your engine and the batteries charge briefly), the meter resets itself to zero. At that point you have lost any data as to how many amp-hours you have used. With the Victron, one can also watch the amps flowing back into the battery to see how you are doing in the struggle to replace the amp-hours you used. Again, I take comfort in knowing that I've used, say, 25.6 amp-hours since I was last at 100%, and now that I'm charging, I can watch that negative number melt away amp-hour by amp-hour toward zero.
 
Thats the one Patrick. It replaced the 600 series that I am using and adds a few more specialty/wireless monitoring features. If you find a deal on the older 600s or the 602 units, they are still a great monitoring tool.

Greg
 
Would the Victron 700 be the one to get since I am only concerned with monitoring the house bank?
Click to expand...
Yes. The 702 model does 2 banks. I saw no reason to do detailed monitoring of the "start" battery. The 702 also has some other fancy features which consider such data as temperature; but again, I felt those features were rather uninteresting to me.

Note: the stunt is btwn the home battery bank negative terminal and all negative wires returning to that bank. That way every electron pulled to/ from the battery gets counted no matter how things are wired up.
 
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