Reply
 
Thread Tools Search this Thread Display Modes
 
Old 09-09-2018, 09:13 AM   #1
Senior Member
 
slowandsteady's Avatar
 
City: North Kingstown, RI
Country: USA
Vessel Model: Mainship 34 III
Join Date: Jul 2013
Posts: 172
Alternator

Late last season the needles on both my tachs, bridge and lower helm, started bouncing. This season neither work and my the gauge says that I am only charging at around 10 volts. There does not seem to be any adverse effects on my batteries. Iím thinking I should get my alternator bench tested. Engine is Perkins 6.354 and I already checked the belt and wire connections. Anyone else experienced this issue?
__________________
Advertisement

slowandsteady is offline   Reply With Quote
Old 09-09-2018, 09:27 AM   #2
Guru
 
djmarchand's Avatar
 
City: Litchfield, Ct/Punta Gorda, Fl
Country: USA
Vessel Model: Atlas Pompano 23
Join Date: Aug 2012
Posts: 4,768
My guess is that the brushes on your alternator started making intermittent contact and that is why your tachs bounced because they pick up their rpm signal from the alternator. Then they finally failed. Ten volts won't do any charging.



So yes get your alternator checked and rebuilt if necessary. A good automotive electrical shop can do it.


David
__________________

djmarchand is online now   Reply With Quote
Old 09-09-2018, 09:41 AM   #3
Guru
 
rochepoint's Avatar
 
City: Sidney BC
Country: Canada
Vessel Name: RochePoint
Vessel Model: 1985 Cheer Men PT38 Sedan
Join Date: Apr 2009
Posts: 1,462
Quote:
Originally Posted by slowandsteady View Post
Late last season the needles on both my tachs, bridge and lower helm, started bouncing. This season neither work and my the gauge says that I am only charging at around 10 volts. There does not seem to be any adverse effects on my batteries. I’m thinking I should get my alternator bench tested. Engine is Perkins 6.354 and I already checked the belt and wire connections. Anyone else experienced this issue?
We had the same problem, turned out to be a bad wire from an oil pressure sender to the exciter terminal on the alternator. This circuit allows the engine to start and develop oil pressure before the alternator puts a charge load on the engine.......

PS...same motor.
__________________
Cheers Mike Barge
RochePoint
Sidney, British Columbia
Yes, I have my "AnchorRight"
rochepoint is offline   Reply With Quote
Old 09-09-2018, 12:12 PM   #4
Guru
 
City: gulf coast
Country: pinellas
Join Date: Jun 2014
Posts: 2,782
Ten volts is not charging at all. Measure the voltage at the battery with a hand held meter with the engine on and off.
bayview is offline   Reply With Quote
Old 09-09-2018, 12:43 PM   #5
Guru
 
Lepke's Avatar
 
City: Between Oregon and Alaska
Country: US
Vessel Name: Charlie Harper
Vessel Model: Wheeler Shipyard 83'
Join Date: Jun 2016
Posts: 1,554
Most auto parts stores will test an alternator for free. If you're handy, you can buy rebuild kits online. I rebuild mine.
New Perkins alternators are under $80 on ebay. Probably $300 from Perkins.
Lepke is offline   Reply With Quote
Old 09-09-2018, 04:22 PM   #6
Guru
 
kchace's Avatar
 
City: Brookline, NH
Country: USA
Vessel Name: Blue Heaven
Vessel Model: Albin 43 classic double cabin, twin 135 Lehmans
Join Date: Sep 2013
Posts: 1,581
At 10 volts you're not charging at all. In fact the battery is getting very low. Not only are you not charging but I suspect there are other issues because if the battery is actually at 10v it is about completely dead.

Ken
kchace is offline   Reply With Quote
Old 09-10-2018, 11:43 AM   #7
TF Site Team
 
FlyWright's Avatar
 
City: California Delta and SF Bay
Country: Sacramento, CA, USA (boat in Vallejo)
Vessel Name: FlyWright
Vessel Model: Marshall Californian 34 LRC
Join Date: Apr 2008
Posts: 12,295
I recently had to replace my start battery for the 2nd time in a year. Turned out that the cause was my port alternator diode had shorted, not blown. The alternator would charge properly when running but after shutdown, the short would drain the start battery slowly.

I discovered the problem by disconnecting the alternator charge cable from the start battery and watched the start battery voltage recover. When the cable was reconnected with the engine off, the battery voltage began to drop again. A bench test confirmed the problem.

I'm not saying this is the same as your problem but alternators can sometimes cause battery problems that you might not expect.
__________________
My boat is my ark. It's my mobile treehouse and my floating fishing cabin. It's my retreat and my respite. Everyday I thank God I have a boat! -Al

@DeltaBridges - 25 Delta Bridges in 25 Days
FlyWright is offline   Reply With Quote
Old 09-11-2018, 08:09 AM   #8
Senior Member
 
slowandsteady's Avatar
 
City: North Kingstown, RI
Country: USA
Vessel Model: Mainship 34 III
Join Date: Jul 2013
Posts: 172
Definitely pulling it this week and bringing to a shop to get it looked at/repaired.
__________________

slowandsteady is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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





All times are GMT -5. The time now is 08:04 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012
×