May. 19, 2005 - electrical

I did forget to mention that I stuck a meter across the batteries this weekend, while on the shore power/charger unit, and measured 13.8V, so nowt wrong with the meter... there is clearly still a problem in my alternator charging circuit that I need to track down...

Given that the Alternator has been tested out as perfect, there can really only be three areas that are the cause

1] The SurePower charge splitter (which is a high tech equivalent of a splitter diode)

2] The cable from the Alternator to the splitter

3] The Excitor circuit

Now....looking at the Sure Power unit, I previous stuck a meter across it, and measured very low voltage at the input, and virtually no resistance across the path to the battery, but very high resistance between batteries. That would seem to be the symptoms of a healthy unit

I still haven't tested out the cable, partially because I'm not sure what resistance to look for, and its not easy to put the meter on when the engne is running to measure voltage behind the alternator, or voltage across the cable because access to the back of the alternator is limted, and very close to the spinning alternator belt....

The last thing is the excitor circuit. This might be easier to test, partially because I can switch on the engine circuit, and see if their is 12V at the alternator without starting the engine.

Looking at the circuit diagrams that came with the boat, there is a diode in the excitor circuit. I am assuming that this is to drop 0.7V to the alternator in order to lift the overall charging output, and hence charge the batteries better. It is possible that this diode has failed.... and as a consequence, the Alternator isn't getting excited, and hence no output.... just a thought...

So, I'll start with that... easily dealt with if its the problem...bypass temporarily to get a charge circuit working, and order a new diode and replace as soon as possible....

Otherwise, I figure it must be the cabling.....

Sadly I'm not sailing this weekend.... SWMBO and I are taking a long weekend trip to Paris....