20 years without knowing, So I thought I'd ask. - Page 5 - SailNet Community

   Search Sailnet:

 forums  store  

Quick Menu
Boat Reviews  
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Hatches and Portlights
Interior And Galley
Marine Electronics
Other Items
Plumbing and Pumps
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here

Go Back   SailNet Community > On Board > Gear & Maintenance > Engines > Diesel
 Not a Member? 
Old 12-10-2011
Join Date: Jul 2007
Location: Truckee, CA
Posts: 8,591
Thanks: 2
Thanked 116 Times in 114 Posts
Rep Power: 0
dabnis is on a distinguished road
Originally Posted by Rockter View Post

Many ships, like mine, need a live ignition to excite the alternator rotor. I have one of those early, and reliable, Ample Power regulators from 1992.

If I turn the ignition off though, I simply do not charge.

I am puzzled as to how any other system would work? How would the alternator be regulated without a power supply? How would it charge?

I don't think it does any harm to my system to turn it off when engine is running, but I simply try never to do it. It has happened every now and again. All that happens is that the alternator amperage just drops to zero.
From an earlier post:

#19 (permalink) 3 Weeks Ago - Add Post To Favorites
Senior Member Join Date: Jul 2007
Posts: 528
Rep Power: 5

Originally Posted by casey1999
The Yanmar manual states (and I think most engine manuals) the alternator can be damaged (rectifier I think gets damaged) if the alternator is disconnected from the battery when the alternator is spinning. Can this happen even if your alternator is self exciting? How is the rectifier actually damaged?

Two possibilities, I think?

1. If the alternator doesn't "see" battery it won't charge, no damage?

2. If it "sees" battery and tries to charge into a "no load" condition the diodes, (rectifier) can be damaged?

By mistake I ran an alternator "open" for a short time and got away with it. from what I have read I was lucky.

Reply With Quote Quick reply to this message Share with Facebook
Old 12-10-2011
Senior Member
Join Date: Oct 2011
Location: Naniamo B.C.
Posts: 2,247
Thanks: 2
Thanked 43 Times in 43 Posts
Rep Power: 4
Capt Len is on a distinguished road
As an aside to the potential damage to alternator, turning the key off prematurely will turn off oil alarm .So now you pull the stop cord or whatever you have. No way of knowing if engine has actually stopped what with all the partying going on in the cockpit and you release the cord early.Engine gives it's last gasp and bounces on compression sucking salt water into cylinder from manifold, bending one or more con rods I can hear you say "'Only an idiot would do that!" Fortunately the insurgency company paid me for my time and parts and the bruises on my butt are finally fading.
Reply With Quote Quick reply to this message Share with Facebook

Quick Reply

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Good Years and Bad Years MooreVOLS Boat Review and Purchase Forum 7 08-26-2010 11:04 AM
your boat for 2 years, my house for 2 years wantogonow Cruising & Liveaboard Forum 0 08-27-2009 04:42 PM

All times are GMT -4. The time now is 04:26 PM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2015, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.