Alternator problem

[fryedaze]

I have a friend who has an alternator doing this. He thinks it is internal regulation. Any ideas??
Video attached

New video by Dave Frye

photos.app.goo.gl

 

[O C Diver]

Probably brushes are worn out. The regulator appears to be working as the voltage isn't going above maybe 13.8 volts. When it drops to 12 volts, the brushes aren't making contact and the gauge is reading battery voltage.

Ted

 

[fryedaze]

It's a new alternator. Boats a 1999 Bayliner 4087. 6BT5.9. 250 HP

 

[Bmarler]

New alternators are sometimes bad. The regulator is simply turning on and off for some reason. I would exchange it for a different one.

 

[luna]

Could it be that this engine or boat has an intake air heater or some other high current consumer that is cycling on and off?

 

[Puffin_NT32]

If this is a JWAC 6BTA, your grid air heater will pull a lot of amps until engine reaches shutoff temp. I disconnected all grid heater components. Not necessary. If this is the standard Delco Remy 105 amps alternator, take it to a NAPA and have it tested. Over 19 years I've rebuilt my Delco alternator several times, to include a 160 amp stator.

 

[TowLou]

Verify with meter? What motor? Is this just after starting and does it level off after coming up to temps? Is there change in the sound of the motor when it drops? I seen Cummins pull a lot of amps when first started hearing the alternator go full field on the road side. Still have a 2012 ram with 6.9 Cummins that does that when first started.

 

[fryedaze]

Verify with meter? What motor? Is this just after starting and does it level off after coming up to temps? Is there change in the sound of the motor when it drops? I seen Cummins pull a lot of amps when first started hearing the alternator go full field on the road side. Still have a 2012 ram with 6.9 Cummins that does that when first started.

250hp Cummins 6BT. He has figured it out but I don't know what he found.