Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 12-09-2011, 19:54   #1
Registered User
 
duefocena's Avatar

Join Date: Aug 2010
Location: Newport Beach, CA.
Boat: TPI Lagoon Catamaran 42'
Posts: 234
Images: 1
Alternator Light On and Tach Out

Anyone have an idea why my altenator light is staying on even though the alternator is charging? Also my Tach went out. I discharged the batteries and then started diesel to see if the alternator charged and it did. Also to make sure the charging system wasn't full which I heard can cause the alternator not to read.
Any help out there?
__________________

__________________
duefocena is offline   Reply With Quote
Old 17-09-2011, 05:19   #2
Registered User
 
Hydra's Avatar

Join Date: May 2009
Location: Lorient, Brittany, France
Boat: Gib'Sea 302, 30' - Hydra
Posts: 1,229
Re: Alternator Light On and Tach Out

Maybe a disconnected wire between the engine and the control panel? I suggest that you test all connexions with a voltmeter.

Alain
__________________

__________________
Hydra is offline   Reply With Quote
Old 17-09-2011, 05:57   #3
Senior Cruiser
 
Vamonos's Avatar

Cruisers Forum Supporter

Join Date: May 2011
Boat: Pearson 385
Posts: 179
Re: Alternator Light On and Tach Out

I have no idea what alternator you have but I just had the alternator rebuilt on my Perkins 4.108. It had a strange connector that I wasn't familiar with from my automotive background. Since diesel engines don't have ignition systems, you can no longer get a tachometer signal from the ignition. There is a separate winding in some alternators (intended for diesel engines) that provides the tachometer signal.

Richard
__________________
Vamonos is offline   Reply With Quote
Old 17-09-2011, 09:52   #4
Registered User
 
Svsilvergirl's Avatar

Join Date: Jun 2011
Location: Oregon
Boat: 1974 islander 44
Posts: 198
On my boat , the "ignition switch" both energizes the alternator and power to the gages . On several occasions the ignition switch got bumped off while the engine was running , and it would cause the exact scenario you just described . The motor remains running until you kill the fuel with the fuel shut off solenoid , but the tach shuts down and the alternator light comes on . The key on my boat is inconveniently located freight behind one of the lazarette doors , and can easily be bumped to the off position when you are digging four something in the bottomless pit. So maybe your ignition switch is intermittently failing or faulty
__________________
Svsilvergirl is offline   Reply With Quote
Old 17-09-2011, 10:00   #5
Registered User
 
Dennis.G's Avatar

Join Date: May 2011
Location: Sea of Cortez and the U.P. of Michigan
Boat: Celestial 48
Posts: 750
Re: Alternator Light On and Tach Out

Vamonos likely has answer. There will be a separate wire from your alternator giving a signal to the tach. Alternator will still charge without this wire, but you will see 0 RPM. Alternator warning light - not sure, but they are wired in different ways and might be same issue as tach.
__________________
Dennis.G is offline   Reply With Quote
Old 19-09-2011, 09:52   #6
Senior Cruiser

Cruisers Forum Supporter

Join Date: Mar 2007
Location: Santa Cruz
Boat: Boatless Again
Posts: 4,314
Re: Alternator Light On and Tach Out

Are you SURE you are charging?? Your symptoms are the classic signs that you aren't. Unless someone's been messing around with both the ignition AND the tach wiring, your alternator is probably not putting out. Measure between ground and the output terminal of the alternator when the engine is running--should be about 14 volts, and higher than the voltage across the battery terminals.
__________________
donradcliffe is offline   Reply With Quote
Old 19-09-2011, 10:00   #7
Registered User
 
duefocena's Avatar

Join Date: Aug 2010
Location: Newport Beach, CA.
Boat: TPI Lagoon Catamaran 42'
Posts: 234
Images: 1
Re: Alternator Light On and Tach Out

Hey Don,

Thanks for your input.

I ran batteries down to 12 volts then fired that engine ( twin engined sail boat= double trouble) and they started charging so I feel confident the alternator is working. Shows 14.5 on my guages.
__________________
duefocena is offline   Reply With Quote
Old 19-09-2011, 10:02   #8
Registered User

Join Date: May 2008
Posts: 1,965
Re: Alternator Light On and Tach Out

Did the tach work when you were charging after discharging the batteries? The most common cause of tachs dropping out is when the batteries are full and the alternator stops charging. The tach signal can go away. In this situation, the tach will work again if you turn on some load - such as several lights so the alternator starts charging again.

It sounds to me like the alternator isn't working (or working sporadically) for a different reason. It could be the alternator or the regulator. Remove and clean to shiny all screw wire connections. Most regulators have a few fuses. Check all with a multimeter. They can sometimes look OK but are blown.

Carl
__________________
CarlF is offline   Reply With Quote
Old 19-09-2011, 10:08   #9
Registered User
 
duefocena's Avatar

Join Date: Aug 2010
Location: Newport Beach, CA.
Boat: TPI Lagoon Catamaran 42'
Posts: 234
Images: 1
Re: Alternator Light On and Tach Out

Thanks for the reply Carl,

I removed the alternator and had it checked. It's putting out 14.5. I am at sea right now ( heading for a haul out up the coast) and have everything on, Radar, radios, 2 chart plotters, refridge, etc. and all is charging but no tach and alternator light still on the starboard engine panel. Gotta be a short somewhere.
__________________
duefocena is offline   Reply With Quote
Old 19-09-2011, 10:34   #10
Registered User
 
Dsanduril's Avatar

Join Date: Aug 2011
Location: South Pacific
Boat: Outremer 50S
Posts: 1,451
Re: Alternator Light On and Tach Out

What Vamonos said.

Most current marine diesel manufactures use the alternator to provide the tach signal (Volvo used to use a magnet on the flywheel with a pickup sensor, but they have switched to the alternator as well, I know that most Yanmars use the alternator, and several others I have seen, but don't know as well). Amongst other things that means that changing the pulley ratio on your alternator will affect your tach.

Anyway, in this situation there should be a minimum of three different connections to the alternator:

1. the charging connection

2. the field connection (which comes through the ignition circuit and the regulator [if external])

3. the tach signal.

Don't know if the tach signal is also used to run the charging light, but I would start with the tach signal wire, run a temporary wire straight from the alternator to the instrument panel and bypass the harness and see what happens.

(BTW, just did this yesterday on a Yanmar, and found that there was a broken wire in the harness somewhere deep in the engine. Routed a new wire with the harness and all works fine).
__________________
Dsanduril is offline   Reply With Quote
Old 19-09-2011, 10:43   #11
Registered User
 
duefocena's Avatar

Join Date: Aug 2010
Location: Newport Beach, CA.
Boat: TPI Lagoon Catamaran 42'
Posts: 234
Images: 1
Re: Alternator Light On and Tach Out

Vamanos,
Thanks for the reply. I run one Volvo and one Perkins. They are very similar as Volvo bought the rights to the Perkins Parama M 30 and produce it as a Volvo 2030. The original engine ( Perkins) is the one I am having difficulty with. It has a larger alternator, with what appears to be external regulator.
__________________
duefocena is offline   Reply With Quote
Old 19-09-2011, 10:53   #12
Registered User
 
duefocena's Avatar

Join Date: Aug 2010
Location: Newport Beach, CA.
Boat: TPI Lagoon Catamaran 42'
Posts: 234
Images: 1
Re: Alternator Light On and Tach Out

Dsanduril,
The bottom of your message didn't come through. Where you started to list something only the 1. bullet mark came through.
__________________
duefocena is offline   Reply With Quote
Old 19-09-2011, 10:54   #13
Registered User

Join Date: Oct 2010
Location: North Palm Beach, Fl.
Boat: Westerly Corsair 36' "Stargazer"
Posts: 140
Re: Alternator Light On and Tach Out

The external regulator is most likely to be the culprit. Just replaced mine to the tune of $600.00 USD
__________________
clifford sloan is offline   Reply With Quote
Old 19-09-2011, 10:58   #14
Registered User
 
duefocena's Avatar

Join Date: Aug 2010
Location: Newport Beach, CA.
Boat: TPI Lagoon Catamaran 42'
Posts: 234
Images: 1
Re: Alternator Light On and Tach Out

Holy Smokes Cliff,

Does yours make beer or something? THat seems really high. Here in Newport Beach they'll rebuild the whole thing for $200.
__________________
duefocena is offline   Reply With Quote
Old 19-09-2011, 13:02   #15
Senior Cruiser

Cruisers Forum Supporter

Join Date: Mar 2007
Location: Santa Cruz
Boat: Boatless Again
Posts: 4,314
Re: Alternator Light On and Tach Out

Here is a pretty good description of the alternator warning light for most systems with internal regulation:

Understanding Alternators, How Alternators Work

Here is a good source for external regulator wiring--the color codes are pretty standardized.

http://www.balmar.net/PDF/Max%20Charge%20MC-612.pdf
__________________

__________________
donradcliffe is offline   Reply With Quote
Reply

Tags
alternator

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 15:16.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.