Keith M

It is possible that the output voltage of the charger has been re-configured What part of the UK is your mooring I may be able to help?

If you go back to about 2016 Mastervolt did produce a chargemaster 12 /100 with at least two outlets maybe three

Is this unit a Chargemaster or a Chargemaster plus? If a chargemaster plus was the activation steps followed? If the unit is under two years old it should be cover by Mastervolts warranty, who undertook the installations and this should be your first call.

It may have been a poor fitting plug or a substandard plug and socket

I am sorry but I have to disagree During all of my AC training which is still ongoing, I have always been told 20 mA has and can be fatal, this is why certain installation requires the use of a 10 mA RCD and normal domestic installation have 30 mA

Within an AC circuit with the voltage at 230 volts, 20 mA is enough to upset your heart.

A selection of wago connectors should be in every boater's onboard repair bits.

I would use a wago type connector this will give a significantly better termination.

It is difficult to keep track of all of the posts

Yes, that is correct will 12 amps be enough?

It is very poor practice to take a 12-volt supply from a 24-volt battery bank, always us a DC / DC converter 24 in 12-volts out. It will just wreck batteries. I have worked with marine electrical installation for more than 30years I have never come across the Vanner unit. As an aside looking at the images of the batteries are the interconnecting cables the same cross-section area.

You could just buy the metal screw at Midland Chandlers. They cannot be that expensive?

What for the hire boats to arrive?

I have always been taught that the hot water always goes to the top of the coil and as the water coolers it falls to the bottom of the coil to return to the engine.