fridge help required. 12/240v

[Phill]

I have just removed my fridge in order to give it a good clean up. (Glad I did. How does all that dirt get in behind it?)
It was connected directly to 12v and the only on/off switch being the thermostat inside the fridge. I have now found a mains cable from the back of the fridge that has never been used.
As I now have shore power I would like to plug in to 240v and use mains when in marina and switch to 12v when away.
If I did this, would I have to switch off mains at the fridge then switch on 12V or would it be ok to have both voltages running to the fridge at the same time.
The fridge is an Engel SRT563 which I think is late 1970's.

 

[Phoenix of Hamble]

Surely if you have shore power charging your batteries, its easier to just leave it on 12V, and let the shore power/charger handle the load?

 

[Phill]

I could do that but I have convinced myself it gets colder quicker on 240v.

 

[Phoenix of Hamble]

Just leave it on if you are on shore power...... if you turn it down before leaving the boat, it'll stay pretty cold, and use v small amount of power, and then can get v cold quickly when turned up upon arrival back at the boat.....

Thats what we do anyway.... and our electricity bills aren't very big!

 

[pvb]

Doubtful...

Most Engel fridges use an AC-powered "swing motor" compressor, which will have the same cooling power whether it's running on mains or 12v. Many Engels have an auto-switching feature so they'll automatically use mains power if this is available. Might be worth investigating this for your installation.

 

[Phill]

Re: Doubtful...

How do I know if its auto switching?
I guess I could just plug it in to mains whilst connected to 12V but how would I know which voltage its running on? Is there any way of knowing?

 

[Guest]

I don't know the nodel you have - but all fridges I had in Caravans and in my present Holiday Mobile - have had 12v / 240V and gas all connected at same time. The control was on front panel and could be switched to whichever source you required. Gas of course had the terrible "blue" magic eye down in the bottom corner to check for firing of the gas.
Later models had auto change when 240V was supplied ....

 

[guernseyman]

Re: Doubtful...

[ QUOTE ]
how would I know which voltage its running on? Is there any way of knowing?

[/ QUOTE ]

Connect an ammeter in series (with the 12V supply would probably be easier).

 

[pvb]

Ammeter?...

If you have an ammeter on your 12v circuit, this will tell you. Or you could measure the battery voltage and see whether it drops a bit when the fridge turns on.

 

[trouville]

Re: Ammeter?...

Why are boat firdges so expensive?

I will eventually buy an isotherm compressor and cool plate(when i find somewhere to fit it).

Lokking at the "kit" its just as the sealed domestic compressor but costs many times more (depending on the domestic brand) and dosent even come with the "box"

Is that just becouse its for a boat?Or is there a real differance?

 

[Phoenix of Hamble]

Re: Ammeter?...

I've got the Isotherm unit..... its fitted in a reasonably sturdy frame, along with a shock isolating set of rubber mounts.... probably much tougher than the domestic version... but agree, it does seem expensive....

 

[kandoma]

Re: Ammeter?...

back to the original question .... my Engel has 12/240 Volt. Its impossible to use both at the same time. It has two different cables, one for 12 Volt and one for 240. The connectors at the back of the fridge are done in such a way, that only one or the other can be connected. I'm also convinced, that the Engel is freezing much faster on mains.

Peter

 

[Phill]

Re: Ammeter?...

[ QUOTE ]
back to the original question .... my Engel has 12/240 Volt. Its impossible to use both at the same time. It has two different cables, one for 12 Volt and one for 240. The connectors at the back of the fridge are done in such a way, that only one or the other can be connected. I'm also convinced, that the Engel is freezing much faster on mains.

Peter

[/ QUOTE ]

Peter
Mine has a 12volt cable and a mains cable at the back. They can both be plugged in at the same time but presumably the fridge chooses 240v over 12v if both systems are live. Is this not the case with yours?. Are you saying you cannot connect mains and 12V at the same time or you cannot use mains and 12v at the same time.

Phill

 

[absit_omen]

Re: Ammeter?...

I had a new fridge fitted last year. The kit used to convert automatically from 240v to 12v (when we disconnect shorepower) was a rectifier. It works perfectly.

That is the limit of my electrical knowledge!

 

[dick_james]

Re: Ammeter?...

Yes it's because of the marine factor. There was a thread about this a while back and apparently the compressor is mains voltage with a built in inverter.

 

[FlyingDutchman]

Re: Ammeter?...

Interesting!
If the boat fridges are really 220 V with a built in inverter 12 V -> 220 V would it not be a cheeper option to buy a minibar fridge and an inverter?

 

[Piddy]

12v/240v

Don't forget that when you are charging batteries (after a long trip for instance) running the fridge on 12v will effectively cut the amount of charge going into the battery. My old fridge (without mains option) uses about 5Amps when running. That's 13% of the output from a 40A charger, which inevitably means a longer charging time.
If it's a short stay to shop and charge up (which we do) that can make a considerable diference, particularly if the fridge works better on mains. I have always understood that if the fridge has a 240v option it would have an auto changeover.
Cheers