Alternators - Safe running temperature question

[BGW]

Sorry but that's technical nonsense. The alternator and the batteries are in parallel. In a simple alternator plus batteries only system, current flows out of the alternator and into the batteries because the voltage at the alternator is higher than that of the batteries.

Yes, you are correct - I am by no means an expert, and I was badly describing what you are saying, that all the electrical flow should be going through the ammeter, to the batteries and inverter.
If the Inverter is drawing 40AH the ammeter should show that as a minimum if it is keeping up with that draw, plus any charge that is going into the battery or other items.
With regard to the charging capacity, I can only quote from my experience, and know that my new bigger bank is able to accept (for whatever reason) a faster charge from exactly the same charging setup - Don't forget I have a Sterling alternator charger - and this works in a significantly different way to a standard alternator setup. It works just like a mains three stage charger.
Perhaps this makes a difference.

 

[stuhaynes]

If I may address the heat of the alternator and the requirement of cooling. Like you, I found my alternator was quite hot and was advised that normally on a vehicle there would be plenty of air circulating to keep it cool. In a boat, in an enclosed atmosphere there is not the same airflow. The fan blades on the alternator will pull air through the workings and the trick was to supply extra cool air. I subsequently fixed up some 4" foil ducting from one of the engine room air vents to the back of the alternator which allowed the alternator to run much cooler.

Yes, the alternator is in an enclosed space and as well as replacing the 1000w immersion with a 500w unit (if I can find one) we're looking for a pair of 150mm circular grills to fit on the engine cover that's in the main cabin. Bearing in mind that the engine cover in the cabin is a piece of mahogany furniture in its own right, we'd like to find grills that won't look out of place. Any ideas out there?