Alternator not old & not working.

[Hoohaa]

I have a new motor with 250 hours on it.
I just had the pulley changed on the front of the alternator yesterday as it was chewing up fan belts, and now when I've reinstalled it. It's no longer charging and the taco has stopped working.
We had a bit of trouble getting the pulley off with a rattle gun.
I'm pretty confident that the wiring is correct.
Does anyone have any ideas on what might be going on here?
Jeff.

[tkeithlu]

Hmmm. First I'd make very sure that the wiring is right and has good connections, because that's the obvious cause.

Question about pulling the pulley - the usual cause of eating belts is misalignment, not a problem with the pulley itself. What led you to pulling it?

If it tests bad, take it to an automotive parts store and get them to run it on their test machine - that's usually a free service because they want to sell you an alternator.

A $30 battery/alternator tester is useful in these situations:

https://www.amazon.com/KONNWEI-100-2...TESTING_DEVICE

Sorry I can't be more specific. Perhaps an alternator guru will speak up.

[Sailmonkey]

I hate when my tacos [emoji895] stop working.

[Hoohaa]

Originally Posted by tkeithlu

Hmmm. First I'd make very sure that the wiring is right and has good connections, because that's the obvious cause.

Question about pulling the pulley - the usual cause of eating belts is misalignment, not a problem with the pulley itself. What led you to pulling it?

If it tests bad, take it to an automotive parts store and get them to run it on their test machine - that's usually a free service because they want to sell you an alternator.

A $30 battery/alternator tester is useful in these situations:

https://www.amazon.com/KONNWEI-100-2...TESTING_DEVICE

Sorry I can't be more specific. Perhaps an alternator guru will speak up.

Wiring was my initial thought. I've replaced the connectors so I'm shore that join is good. But that wire attaches deep inside the alternator so I'm thinking of pulling it apart to check that it's well connected.
Regarding the pulley. The alignment is good but the wear marks indicated that the belts were riding all the way down on the bottom of the pulley. It wasn't machined with the correct camber.

[Hartleyg]

The fact that the tach ("taco") isn't working says the alternator doesn't have any field current.

Do you have an internal regulator or external? If its internal, then either something has come adrift or there is no battery connected to the alternator. The alternator has to have field current to begin producing charge, so if you don't connect a battery, it won't do anything. Some alternators might have a different connection to power it - for example, the "ignition" lead, which goes "hot" when you turn the engine on.
If you have an external regulator, then it should have some LEDs or other display to tell you what its up to.


Pictures often tell mare than 1000 words worth


Hartley
S/V Atsa

[Hoohaa]

Originally Posted by Hartleyg

The fact that the tach ("taco") isn't working says the alternator doesn't have any field current.

Do you have an internal regulator or external? If its internal, then either something has come adrift or there is no battery connected to the alternator. The alternator has to have field current to begin producing charge, so if you don't connect a battery, it won't do anything. Some alternators might have a different connection to power it - for example, the "ignition" lead, which goes "hot" when you turn the engine on.
If you have an external regulator, then it should have some LEDs or other display to tell you what its up to.


Pictures often tell mare than 1000 words worth


Hartley
S/V Atsa

Internal reg.
I'm sort of in your camp with something coming adrift. It was quite an effort with the rattle gun to get that pulley off.
Here's a pic. I will try and get some more.

[Hartleyg]

OK, Hoohah - yes, definitely internally regulated.


I see three wires connectingto the aft end of the alternator - a small blue one, a smallish black and a slightly larger red, which is affixed to the larger terminal bolt.


When you are either running the engine or have the switch on, what voltages are on each of these leads? I would think the larger red one should be battery, therefore +12V to chassis. If not, then find out why. the blue is likely the tach - there will be some AC there once the engine is running and the alternator charging. Not sure about the smaller black, but it might be that "ignition" lead I talked about. If so, it should have battery voltage on it when the switch is on. With an internal regulator, there isn't much else.


Edit to add: clearly, this is not a small boat (nice engine access!) - if you are cruising, you may want to consider an alternator with an external regulator to get the best charging regimen from your setup. Built in regulators tend to be VERY stupid things, and will eventually either over-charge or under-charge your battery bank.
Another aside - we had a "burning off the belt" situation on our boat, too - the OO installed a large alternator, but did not upgrade the belt to match, so we were burning off a belt every month or so(annoying does not begin to describe it). Cutting the maximum charge back to 60% using the external regulator (a Balmar 612) solved the problem for good. I now replace the belt every 2 years just for GP.




Hartley
S/V Atsa

[Hoohaa]

The white wire runs to the TACHO it has no effect if it's connected or not. Ive redone the connectors on it so I'm pretty shore it's not a bad wire connection.
I'm thinking it got shaken around by the rattle gun and its broken some soldered points inside.
Can I do much harm by opening it up?

[stormalong]

What do you mean by rattle gun? An air hammer? An impact wrench?

Easy to take apart but tricky to reassemble without experience. You usually need some stiff wire or a couple of paper clips to hold the brushes in the brush holder while re-inserting the rotor. Then pull out the wire. Look carefully and you will see what I mean.

[mikereed100]

I had the exact same problem after installing a brand new alternator. Alternator would not charge, tachometer would not work. I checked and re-checked the wiring as I was sure that was the problem. Made sure all my grounds were good, cleaned or replaced all connectors, etc. In frustration I took the alternator to have it tested and it was fine. When I re-installed it it worked perfectly. I suspect that a bit of insulation from one of my new connectors was caught under a washer, preventing contact. I would recheck all your wiring, looking specifically for something like this.

[Pete7]

In addition to Mikes post, I would suggest those wires are woefully undersized. Volvo have a habit of this. However, if you are expecting 50-100A to flow through the wires then they need to be heavy duty. Just redone mine and moved up to 25mm2 wire, but if you can get 35mm2 then do so.

I see the tacho feed, and the thin black wire for the field wiring, were is the main negative wire, or does it use the case? if so not great, run an new negative wire to the main bus bar.

Pete

[Hoohaa]

I've opened it up. Nothing obvious.
I've attached some pics. Let me know if you can see anything wrong.
Buy the way. This is a Kubota 50hp engine.
I spoke to the guy that built the engine. The white wire is soldered to the diod to give the rpm Meyer the pulse.
Rattle gun is a large air powered impact driver.
My next step is to take it down to an autoelect and get it bench tested.

[Hartleyg]

Hi Hoohah,


One thing your pictures don't show is the condition of the two brushes that contact the sliding contacts on the visible shaft (below the ball bearing). These brushes conduct the field current through the alternator windings to produce output (and the AC the tach needs).



If those are damaged, the alternator will not function - and they are somewhat vulnerable to shock and damage. This would explain your problem if true.


Taking it to an auto alternator shop will be illuminating - and they may be able to supply you with a replacement at reasonable cost


Hartley
S/V Atsa

[Hoohaa]

The second photo on the right hand side. The regulator is sitting on the bench and if you zoom in you can see the two brushes.
They looked pretty good.

[Hartleyg]

Ahh - yes, I see them, and they do look OK. If you have an ohm-meter, the two shaft contacts (not the brushes, the contact surfaces on the shaft) should have a very low resistance between them (but not zero). That will confirm the field winding is good.


We'll all be interested in how the visit to the shop goes


Hartley
S/V Atsa