Exciting the alternator - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance > Engines > Diesel
 Not a Member? 

Diesel This is a forum dedicated to diesel engines and their applicable accessories.


Reply
 
LinkBack Thread Tools
  #1  
Old 07-10-2010
Senior Member
 
Join Date: May 2007
Posts: 547
Thanks: 3
Thanked 3 Times in 3 Posts
Rep Power: 8
SteveInMD is on a distinguished road
Exciting the alternator

I have a Yanmar 4JH2E. I've just replaced the alternator only to find another possible issue. My new alternator will produce power but only after running at cruising RPM for 10 minutes or so. It's a Hitachi N-type alternator with a "T" connector in the back for the "sense" wire and the excitation / warning lamp wire. The sense wire works properly - the charge is correctly regulated (by the internal regulator). The engine panel has no charge warning lamp, which is typically part of the excitation circuit. After much searching I found that the excitation wire simply terminated about half way back to the engine panel. The alternator does start charging immediately by applying 12 volts to the excitation wire.

My questions are -

1) With no excitation current how does the thing ever start charging?

2) Should I attached the excitation wire so it starts charging as soon as I fire up the motor, or is it typical to not connect this wire and wait until the motor is run at cruising speed for a while before charging?

3) If I do connect the excitation wire to the ignition circuit, I believe I would need to add a resistor since I have no warning lamp. What is the proper type / ohm value resistor?

While it's not a huge problem as the alternator does start charging eventually, it seems to me that it would be better to excite the alternator at start up. I don't like using the windless to pull up the anchor with the batteries down a bit after using power all night. I'd rather have them closer to 14 volts as I believe this is better for the windless motor. Does this make sense?
Reply With Quote Share with Facebook
  #2  
Old 07-10-2010
hellosailor's Avatar
Plausible Deniability
 
Join Date: Apr 2006
Posts: 10,620
Thanks: 2
Thanked 89 Times in 87 Posts
Rep Power: 10
hellosailor has a spectacular aura about hellosailor has a spectacular aura about
Steve, your instincts are right on this. Having wires tied and teed and not used is simply quick & dirty, and setting it up with a few more feet of wire and five bucks worth or parts to get it producing power right away is a better way to go.

I wouldn't try to guess what voltage it wants to see on the exciter, but would try to find a schematic for that particular model number. From Hitachi or the folks who sold you the alternator, you should be able to dig something up. Heck, you might be able to find out which bulb they usually use, and simply add a bulb+holder into your panel so you have a charge warning light too!
Reply With Quote Share with Facebook
Reply


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



All times are GMT -4. The time now is 09:54 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, 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.