Caravan vsr for boat fridge?

[KenMcCulloch]

We have a fridge with no thermostat, a eutectic plate type so basically we switch it on when on shore power or - if someone remembers - when motoring. I wondered if one of the small vsrs sold for use with caravan fridges could be used? There used to be a device called a Fridge Mate sold but seems not to be available now. It draws about 4A so does discharge the batteries a fair bit if left on while sailing or at anchor.

With a little vsr we would just turn on the fridge power on opening the boat, and it would only draw power at charging voltages. Any reasons why that would not work? Better solutions?

 

[nigelmercier]

A pair of relays, wired to shore power and ignition circuits.

Or if you have a VSR already, detect when the LED is glowing and fire a relay. Simple circuit, just built one to repeat the LEDs on my computer.

Or a fridge power pack that powers the fridge from shore power, and a relay for the ignition.

 

[pagoda]

We have a fridge with no thermostat, a eutectic plate type so basically we switch it on when on shore power or - if someone remembers - when motoring. I wondered if one of the small vsrs sold for use with caravan fridges could be used? There used to be a device called a Fridge Mate sold but seems not to be available now. It draws about 4A so does discharge the batteries a fair bit if left on while sailing or at anchor.

With a little vsr we would just turn on the fridge power on opening the boat, and it would only draw power at charging voltages. Any reasons why that would not work? Better solutions?

That sounds fairly reasonable. I sort of went the other route. I have a mains operated relay and a 10Amp 12V mains powered adapter. When mains is present, the fridge is mains powered through the 10Amp PSU, not using the battery at all. If mains is absent, the supply reverts to battery. With a clear label at the switch panel about only running when motoring. A VSR would be quite neat as well.

 

[TradewindSailor]

I have a VSR that is rated at 140 amps at 12v and draws less than 1/2 amp. It cuts in at 13.3 V and cuts out at 12.8 V .... so it will protect your batteries. http://enerdrive.com.au/product/voltage-sensitive-relay/

The price is a little variable ..... the cheapest I've seen is AUD 45 ...... all the way up to AUD 110!!!

The circuits are protected against moisture with a thick silicone coating. The voltage sensing circuit drives a solenoid that is inside the sealed case.

There are some programmable VSR's that may be more suitable, but they are a lot more expensive.

 

[maxi77]

I have used these both on boats and motrcaravans with great success.

http://www.brocott.co.uk/split-char...ching-split-charge-relay-12v-30amp-h78-1.html

 

[Zen Zero]

I bought one to fit last year but haven't got round to it yet!

Same idea as yours, a relay to detect charging tension and allow 12v to reach the fridge, or rather to disconnect the fridge when charging tension is not detected (eg we're sailing). One of the main reasons I haven't been bothered to get round to it is that we don't use the fridge any more; well we do but we buy a six pack of frozen 1.5l bottles of mineral water from a grocer and that keeps the fridge cold for about a week.

We have an old 3-way Electrolux Mobicool but ...
1. we never run it on gas for fear of CO
2. we hardly ever hook up to shore power now that we've got a solar panel
3. it is very power-hungry for 12v ampère-hours and we are not good at remembering to turn it off when we're not motoring!

Incidentally, the new generation of compression leisure fridges is very very much more efficient. Her Ladyship and I recently bought a Waeco Tropicool to keep Her Ladyship's diabetes medicine and some other essential items cool on long car journeys. It runs off the lighter socket and turns itself off before draining the battery. The next large purchase for the boat might well be a new generation frigde - if I can get it past the investments board!

 

[nigelmercier]

I have used these both on boats and motrcaravans with great success.
http://www.brocott.co.uk/split-char...ching-split-charge-relay-12v-30amp-h78-1.html

That's a very good price for such a device. I may even buy one for my outboard battery. Note that they do two similar ones, only real difference is the mounting.

 

[KenMcCulloch]

Thanks for the interesting and in some instances useful replies. I will let the panel know how we get on.