Aux alternator not charging house batteries

[jmart91]

Thanks for the thoughts.  I am at a bit of a loss now.  When I put 12V across the exciter terminals I can definitely hear the engine load change, but still see only about 13V (so battery voltage) across the alternator terminals - no change.  That makes me suspect the alternator itself.  I have an electrician scheduled to do some more digging in about 2 weeks. 

My aux electricals are Mastervolt (which I hate because they seem to have completely pulled out of North America) not Balmar, which makes the troubleshooting a little more difficult.

[KPDH49]

Do you have an external regulator? Balmar? If yes, there will be a separate fuse on the regulator power wire. If it

[joel]

Had the same problem as Andy on my 44!  The Yanmar harnesses are undersized.
Ran a new larger wire from the Yanmar panel to the alternators.

Good luck!

Joel

[jmart91]

Thanks for the replies!  I did find the fuses between the two alternators and the batteries - on my boat they are under the port-side chart table, behind the panel with the engine and generator power switches.  I have attached photos - the 200A fuse from the auxiliary alternator is mounted on the hull, directly behind the switch panel.  The 125A fuse from the main alternator is mounted on the bulkhead just aft of the dropdown panel.  In this case, neither fuse was blown, so that is not my problem.

I am working on troubleshooting the excitation power supply (thank you for that suggestion Andy), and think that could be my issue.  Soldered my light bulb test circuit this evening and will see if that gets things running properly.  Will keep you posted.

Jeff

[Knoxan]

I experienced this same problem twice in the last year and both occurances were down to losing the excitation power supply.
If you have a multimeter ( or a light bulb with wire tails) check with the engine control circuit or ignition switched on (engine does not need to run for this) that there is power at the excitation terminal (the one with the small cable(s) attached  at the back of the alternator. More likely the problem than a blown main fuse.
If no power found here check back to the circuit breaker supplying that power and see if power is disrupted there.

In my last case (two weeks ago) the cable crimp on the the excitation terminal was corroded and the wire fell off when I touched it.

For information, the first time this happened I lost excitaion power to both alternators simultaneously. The Yanmar excitation wiring was a mystery to me  and being an electrical engineer I went back to first principles and rewired the whole system.

Andy
H46#32

[Coulesca]

Jeff,  The fuses for the batteries under the owner's cabin berth on my Hylas 49 (hull #59) can be accessed by pulling out the drawers under the berth. The fuse blocks are mounted behind, or on the side of the drawer compartment.
Paul
S/V Coulesca

[Four Winds]

I believe it

[jmart91]

Hi there - I own a Hylas 49 (hull number 62) that has the auxiliary 130A alternator installed.  Right now it is not charging the house batteries as it should.  The schematic shows a 200A fuse between the alternator and the engine switch, which is in addition to the 200A fuse just in front of the batteries under the owner bunk.  Does anyone know where that second fuse is?  In the schematics there is also supposedly a 125A fuse between the standard alternator and the engine start battery, but I cannot find that one either.  I would appreciate any help finding this fuse to see if it is causing the problem!

Jeff Martin
S/V Blackfin