Fridge modification.

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Edwins
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Re: Fridge modification.

Postby Edwins » Tue Nov 14, 2017 10:12 am

Just seen this thread, I have a WEBASTO upright fridge/ freezer with 2 separate doors. it seems to work quite well but does suffer from the on/off/on sindrome.

I think part of the problem is, in hot climates the fridge is partially insulated by being within the vehicle body, and plenty of sun for the solar to keep it working. while in colder climates the fridge is in a heated vehicle body and less solar to keep it going!

My fridge is well vented, with a vent through the floor, but I have just fitted an additional vent at the top of the void behind the fridge that vents into the top of the shower enclosure, to help suck the hot air out. it could also help warm the bathroom and help ventilation there.

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ClivePhoto
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Re: Fridge modification.

Postby ClivePhoto » Fri Nov 24, 2017 9:47 pm

Charles Stirling fridge tests. Interesting comparison between dedicated 12V fridges and a 240V fridge through an inverter.

https://www.youtube.com/watch?v=SUzbp18L9oc

Ivan C
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Re: Fridge modification.

Postby Ivan C » Sun Nov 26, 2017 10:21 pm

Interesting indeed, though from experience I'd be wary of believing anything he said.
I thought it was interesting the way he described 0.3 A as insignificant and 0.5 as significant in the same context.
He also failed to mention the importance of using a fridge with the cooling system to the rear rather than the sides.
His manner, subject knowledge and data recording would not inspire confidence .
Ivan C

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ClivePhoto
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Re: Fridge modification.

Postby ClivePhoto » Mon Nov 27, 2017 10:49 pm

Ivan C wrote:He also failed to mention the importance of using a fridge with the cooling system to the rear rather than the sides.


I suppose they are the way they're built, usually all the cooling stuff is at the back? Unless you mean you should have your fridge in the back of the truck but I can't see what difference that would make.

Ivan C
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Re: Fridge modification.

Postby Ivan C » Tue Nov 28, 2017 10:24 am

Quite a few domestic fridges have the cooling matrix in the sides, it only becomes an issue when they are boxed in, with no clearance, as they would be in a truck or van. From memory some of the narrow boat fridge converters used this type.
I suppose things like this are a consequence of using them in an environment that they weren't designed for.
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Re: Fridge modification.

Postby crinklystarfish » Sat Dec 02, 2017 8:32 am

Overlooking the commentary, it was a useful data comparison at least and the difference in consumption between freezer / no freezer units was interesting.

It would have been interesting there had been an identical rig on which someone opened the door for about 30 seconds once every few hours to see what effect that had on consumption.

I realise it wasn't the intended purpose of the comparison but it would have been interesting to see. I'm betting consumption would have increased dramatically.

Ivan C
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Re: Fridge modification.

Postby Ivan C » Sun Dec 03, 2017 8:51 am

I suppose logically it will take more energy to maintain a freezer than a fridge because of the greater temperature differential.
Another issue, which wouldn't have arisen because he wasn't running off batteries only, is that the start-up surge of the ac motor can pull the battery voltage down below the inverter's shut off point.
I know of at least one case, using a quality inverter, where he eventually changed to a 12v compressor.
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Grommet1
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Re: Fridge modification.

Postby Grommet1 » Sun Dec 03, 2017 9:25 am

That's an important point Ivan. I had the same problem with my inverter constantly alarming on start up in the middle of the night. As the 240v compressor kicks in the current draw would drop the battery voltage sufficient to alarm. Once running it was fine but the alarm was so irritating I ended up going for a 12v compressor waeco. That runs fine off the solar panels and I can just leave it running constantly. The big expense of a 12v fridge over my 80 quid small domestic fridge made me wince though.
Regards John


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