How to Test Charging System?

[Dockhead]

Our boat has a separate 12v alternator charging the starting battery, and a big-azz 100 amp 24v alternator charging the house and service batteries.

I don't think power from the 100-amp alternator is getting to the house and service banks. Batteries seem to be low after a trip, even after a couple of hours of motoring. And I see a "no charge" or "low charge" warning light sometimes while motoring.

How can I test the alternator, and the regulator, to see what the problem is? Is there an accepted procedure for doing this?

Thanks guys.

[GordMay]

See post #1 at
➥ http://www.cruisersforum.com/forums/...sting-375.html

[donradcliffe]

Buy Nigel Calder's book 'Boatowners Mechanical and Electrical Manual'--you may not always have an internet connection when you have a problem, and he does a good job of the procedure for testing the charging system, as well as most other systems on the boat.

The short answer is "what is the voltage across the battery bank(s) when the engine is/is not running? If the voltage does not rise after you start the engine, you have a problem with the 24v charging system--it should be 26-28v with the engine going.

[Dockhead]

Thanks very much. I do have Calder's book! It's on the boat. I'll use it for this. Cheers.

[Dockhead]

And thanks Gord for your excellent paper. I have printed it and will take it on board.