Powering the fridge ...

[dgadee]

OP here. Thanks for all the comments. My thoughts so far:

1. I am surprised that no-one has thought that my original idea of uprating the charger (20a to 60a) would be a good move (to get the most out of the generator in the shortest time). I will put that on the back burner.

2. I do plan to put a couple of hundred watts of solar panel on the boat, and some of you think that might solve my problem. I will see ...

3. The current fridge is a Waeco front door and I usually have it turned down. But it does consume a lot of power. I would prefer something built in with lots of insulation but the only supplier of suitable fronts for building in fridges I could find is in the US and has no UK agent.

4. Extra batteries would need space and in a boat with a shallow bilge, there's not much around. So not sure where I would put even one. Also, you would need to feed these extra batteries, and that is where I see my current problem being.

5. The gas option was for use when moored but with no shore power. Some of you are suggesting sea use, but that wasn't in my thinking. Sorry that I didn't make that clear in my original post. I'm not keen on a gas fridge but have no knowledge of these. I didn't know they still existed until yesterday.

 

[lw395]

I think it helps to be clear what you want from your firdge.
Will you use it all the time?
If all you want is to keep food for a few days, that is mostly about insulation.
If you want to turn lots of warm beer into cold beer, that is about power.
If you want to make ice, that is power.
Are you trying to live out of it for a whole week or more, or are you just wanting a few essentials for a couple of days at a time?

Obviously a front door fridge is not ideal, but for perspective, a domestic fridge from Curry's supposedly uses 117kwh per year. I make that an average of 13W?
So 50Ah of battery capacity might cope with daily charging and something like 100W of solar?

Is it rocket science to DIY a front door fridge with a bit of cold air retention and generous insulation?
Or could one stop the cold air falling out of a Curry's fridge? Some sort of inner door?

 

[dgadee]

I think it helps to be clear what you want from your firdge.

...

Is it rocket science to DIY a front door fridge with a bit of cold air retention and generous insulation?

Just food preservation. I'm a warm beer man and we don't use the freezer compartment. Just got the documents out - fridge is 10 years old and it says 45 watts average usage. May be time to think about a replacement anyway.

I turned a top loading cool box into a fridge not so long ago, but I think a front loading door would be a bit more complex to make it work well. Glacier Bay was the company in the US who made these, but they don't seem to exist anymore.

 

[GHA]

OP here. Thanks for all the comments. My thoughts so far:

1. I am surprised that no-one has thought that my original idea of uprating the charger (20a to 60a) would be a good move (to get the most out of the generator in the shortest time). I will put that on the back burner.

It all depends how much you discharge your batteries every night. Once up 70/80% full it doesn't matter what size of a charger you have, the amount of current they'll accept tails off rapidly so you might save a bit of time if you're discharging down to say 50%, but won't be that great. I run a 10e for an hour or maybe 2 in the morning first thing then solar does the rest if the is sun.

2. I do plan to put a couple of hundred watts of solar panel on the boat, and some of you think that might solve my problem. I will see ...

Probably help loads if there is sun - where are you heading? Tilting panels helps a lot as well, especially if your anchored somewhere tidal.

4. Extra batteries would need space and in a boat with a shallow bilge, there's not much around. So not sure where I would put even one. Also, you would need to feed these extra batteries, and that is where I see my current problem being.

320Ah doesn't sound too bad unless you have a boatfull of guests all running laptops & the TV on. I get by fine with 2 t105 trojans - 225Ah.

 

[macd]

dgadee: it would be helpful if you indicated where you're based. Donaghadee, perhaps?

200W of solar should easily keep up with a fridge's energy needs in summer, except in a succession of grey days which your small battery capacity will be unable to buffer. This is precisely why additional battery capacity is so valuable.

Efficiency is obviously also key: ideally 100mm of good quality insulation (although if you're not interested in ice-cold beer, 75mm would be OK). If air-cooled, as most are, a computer fan wired to circulate air over the cooling coils is worthwhile. These draw very little and can easily be wired to come on only when the compressor is working.

 

[dgadee]

Yes, the sunshine capital of Ireland. Unfortunately, not much sun. But I am (hopefully) off south with the boat to the sun for a couple of years.

Efficiency will be the watch word. I'll do some more thinking with these ideas.

 

[vyv_cox]

I increased my domestic battery bank from 220 to 330 Ah, which made a huge difference. Instead of seeing 12.1 volts in the morning we now see 12.5 or 12.6, dependent upon the time of season.
My fridge is a front opening Waeco, although rather special in that it is water cooled. For living aboard the convenience of being able to see exactly where your food is weighs heavily against a top-loading one and the differences in power consumption, although present, are not that onerous.
We have 125 watts of solar, which we find to be plenty to run everything, April - October.
We are considering adding refrigeration with a holding plate to the cool box but only for use once per day when the sun is at its zenith, just for keeping fruit and vegetables cool. A temperature of around 10C, currently achieved with frozen water bottles when they are available, makes a big difference.

 

[Trundlebug]

I went through a similar fridge repalcement exercise as the OP a couple of years ago, and did a lot of research.
My usage and requirements were similar to the OP - need a freezer compartment for making ice cubes and a few other items, but I didn't need a 5 star rated (3 months storage at minus 18) large freezer section.

As we had a 3 way gas Electrolux fridge originally, which set off the CO alarm one warm still night at 2am despite hatches being open, an efficient 12v compressor fridge was seen as the only solution. Not only that, but gas 3 way fridges are no longer allowed to be fitted in boats under the BSS scheme (a boat MOT which covers all boats used on inland waterways).

After considerable research I fitted a Webasto Isotherm fridge. It has the same Danfoss BD35 compressor as the Waeco, but a smaller freezer compartment that isn't rated as a 3 or 5 star minus 18 job.
It also had the option of Isotherms smart energy control https://www.webasto.com/int/markets...refrigeration-solutions/smart-energy-control/

I also fitted an additional 1" of Kingspan insulation all around the new fridge.
Overnight it uses just 5Ah of power, which is really efficient. I only have 330Ah total, similar to the OP, so with an efficient installation you shouldn't need to enlarge the pack although you can never have too much.