Alternator current dropping slowly after start

[sailorboy1]

Originally Posted by crankysailor

So I measured the voltage at the alternator and there was nothing...

There should always be voltage at the alternator power lug unless there is a switch between the alternator and the battery. Follow the cable all the way back to the batteries and see what is on the line.

[philcun50]

Sailor Boy is right, if the alternator isn’t charging then you should have battery volts back feeding the output terminal but if you mean you have 14.2v then 12.5v that’s different.
In that case sounds very much like brushes. A simple job, hardest part is identifying your alternator. To my mind having a switch between alternator and battery would strange but some like them.

[philcun50]

Having re-read you post I see you measured volts at alternator then relied on battery monitor for next reading. Call me a pedant but I like to be more careful with readings, 55 years as an electrician. Some B (battery) terminal bolt heads on alternators are insulated, CAT machinery with Delco alternators. Readings need to taken on the cable lug. You have wind and solar so the 14.2 volts may well be coming from there, especially now the batteries are fully charged from shore power. So many variables, much more investigation needed before a conclusion can drawn. I don't like spending money.
It can also be in the negative cable run too though if the engine cranks this could say the negative is ok.

[sailingchiro]

I highly recommend a clamp on amp meter for DC and AC. They are only about $50 from Lowes/Home Depot and are valuable when determining the movement of electricity.

That being said. Disconnect solar and wind. Turn off main breaker (load) to house but leave altenator and batteries hooked together. Clamp meter on battery cable (should read low reading or 0 amps). Then turn on engine and check voltage and amps into battery. Of course, you may be having an intermiitant problem, in that case wiggle wires to determine an "open" at battery, altenator, regulator, or inside of altenator. Battery voltage should slowly go up to above 14.5 (or close) volts but amps should be higher. As the batteries charge the voltage will go up and amps will go down until fully charged. The lower the voltage at batteries, the higher the current (amps) will need to charge batteries. If no current( amps) and voltage isn't climbing, then not charging. Altenator rebuild/replace. If good charge but batteries don't hold a charge, bad battery. Of course this is my humble impression and could be way off base.