alternator wired to battery?

[Hammond Eve]

I have a gulfstar 36 1973 trawler. NEW alternators on both perkins diesel 90 hp engines. some instruments do not work. amp meter on stb engine shows amp delivered. amp meter on port engine shows nothing. I assume the alternator is working, but dont know if the amp meter is bad or the wiring is bad. Wiring to the alternators was detached when i got it,as the previous owner described himself as a marina hopper and apparently could get from one marina hookup to the next without depleting the batteries or charging them.

I tried matching the dangling ends of the wires related to the alternators. that worked with stb but not port engine. the two systems are isolated. is there a way to run the connection directly from the alternator to the battery and avoid any flaws that may exist in the maze of wiring running into the various harnesses and instruments on the control panel?

 

[KnotYet]

You may only have one working alternator. Not knowing anything about your boat's
installation specifics makes it harder to offer advice but here's what I'd do.
Keep the working alternator connected to the battery switch I assume you have.
If there is no battery switch, get one and install it near the electric panel.
If you have only one battery, connect that to the batt 1 post on the switch.
Make all connections like the starter and house panel to the battery switch output.

Get the non-working alternator tested and repaired if necessary.
You need both, if only for redundancy. Add a second battery as your budget allows.
Once you have two working alternators you can add a battery combiner/Duo-Charge.

Another thing that occurs to me is the dead ammeter's shunt.
On my boat the shunt had corroded to the point of disfunction.
New shunts are available but I would probably get a new meter, too.

 

[Hammond Eve]

thank you. all in your first paragraph is how it is now wired to battery switch. i hve 2 batteries, separated at switch. the ammeter issue is something i was wondering about. if the meter is not working does that prevent the charge from going from the alternator to the battery? i am going to look at it for the shunt issue you mentioned.

 

[FlyWright]

When I recabled my boat and directed the alternator charges straight to the battery banks (fused), I lost ammeter function due to the ammeter shunt wiring being bypassed by the new cable route I created. The original cabling used the start cables to deliver the alternator charges to the batteries which prevented me from separating loads from charges as I was accustomed to on aircraft systems.

I pulled the ammeters and installed a Battery SOC meter in its place and can verify house charge current and start and house bank voltages. I'm much happier with the digital display and greater info. I really didn't need the current flow into the start battery as the voltage gives me the info I need.

Now I have a system that allows me full control of loads and charges, each independent of the other.

 

[KnotYet]

If wired correctly, the ammeter will not impact the alternator's output.
You can use a basic VOM to check the alternator.
Look for a rise in voltage when the engine in question is running.
If the battery and alternator are healthy it should be above 13.5 V or so.

 

[Hammond Eve]

that is very helpful. thank you.i am seeing my way out of this situation now.

 

[C lectric]

Check the small wiring at the shunts. The shunt produces little current and low voltage which the ammeter reads. If the wiring between the shunt and the ammeter has poor crimps or dirty connection it can totally defeat the unit.

I had this years ago and just reterminating the wires, both ends, got the ammeter working again.

 

[FF]

"When I recabled my boat and directed the alternator charges straight to the battery banks (fused),"




This is dangerous as blowing the alt output fuse while in operation usually blows the alt diodes.

Battery selection /disconnect rotary switches usually have a field disconnect to avoid blown alts should someone make a mistake with the engine operating.