Can anyone confirm that I'm thinking along the 'right lines' here.
Having very recently bought a 3 year old Viking 24, which is fitted with an Engel 12V fridge.
When we took the boat out for the first time last weekend, running for 3 or 4 hours, the fridge got nice and cold.
On thursday, I went up to the boat to spend a couple of days, doing some work on it, and staying over night. The boat was 'hooked up' to 230V shore power. In order to have fridge on, without draining the battery, I put connected a battery charger to the battery, and let it run in 'float charge' mode.
However, the fridge did not get cold.
I assumed that, like my caravan fridge (a Dometic 12V, Gas, Mains), while towing, 12V is only connected to the fridge when the engine is running (a voltage sensing relay in the car takes care of this). As the Dometic fridge will draw up to 10 Amps from the car supply, this prevents the flattening the car battery, when the engine is off, but the fridge still connected to the car.
I believe the Engel fridge only draws something like 3.5 Amps, but obviously enough to drain a battery over several hours.
If it is the case, that the boat fridge is only activated via the ignition switch circuit, then I will need the wire in a bypass switch, so that I can run the fridge on the 12V system, when on the marina mooring with the ignition circuit switched off. The 230V 'shore supply' powering a battery charger in 'float mode', maintaining the battery power.
What is confusing, is that with the shore power connected, I can here what sounds like a fridge compressor running all the time. The sound coming from the vent below the fridge. Switching the fridge to off, via it's internal switch, has no effect on this compressor type noise. Switching off the whole of the 12V at the isolator, also has no effect.
Disconnect the 230V shore power supply, and the noise stops.
Any thoughts on this ?
Dave