Cruisers Forum

Join CruisersForum Today

  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
Thread Tools Search this Thread Rate Thread Display Modes
Old 31-03-2010, 08:35   #1
Registered User

Join Date: Nov 2008
Location: Nevis, WI
Boat: Corbin 39, 'Pinguescence'
Posts: 23
Help Needed! - Wiring Alternator to Charge House Batteries

New engine comes fully wired, and the alternator is prewired to charge the battery that connects to the starter motor. Of course, that battery is my dedicated engine starting battery, which I use for nothing more than starting the engine. The old engine which I just replaced had an alternator with a large ground stud as well as the positive connection, so I connected the alternator to a diode onto which I then connected the house batteries and the engine starting batteries. It was a lot of wiring. I am wondering whether I can charge the house banks by simply connecting them to the engine starting battery using the 'both' switch on my battery selector switch?? Can anyone help?

cgaskell is offline   Reply With Quote
Old 31-03-2010, 08:54   #2
Registered User

Join Date: Dec 2009
Posts: 2,959
Images: 4
Yes, it takes some remembering, but you could switch to BOTH while motoring. Then back before shutting down....depending...will help if all batteries are the same general type...flooded...AGM...etc. You can buy a little relay box from West MArine that does this automatically. Diodes are problematic.

daddle is offline   Reply With Quote
Old 31-03-2010, 10:20   #3
Registered User
SvenG's Avatar

Join Date: Oct 2009
Location: Mexico heading South
Boat: Ericson 39B - Senta II
Posts: 1,169
Originally Posted by daddle View Post
Yes, it takes some remembering, but you could switch to BOTH while motoring. Then back before shutting down
I would switch AFTER shutting down the engine. We have the standard Guest make-before-break two bank switch/breaker. Despite its design, switching from 1 to both or both to 2 etc. will cause instruments to beep as they reset. I assume the problem is due to corrosion or oxidation on the switch contacts. Given the danger of blowing the alternator by having it disconnected momentarily from the battery load I never switch battery settings with the engine running.

Overcautious ? Maybe.

Senta II -
1977 Ericson 39B -- Hull # 216
SvenG is offline   Reply With Quote
Old 31-03-2010, 10:42   #4
Senior Cruiser
GordMay's Avatar

Cruisers Forum Supporter

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 37,062
Images: 241
See the Blue Sea Systems Application Briefs on Battery Switching
Resources - Blue Sea Systems
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"

GordMay is offline   Reply With Quote
Old 31-03-2010, 10:45   #5
Eternal Member

Join Date: Jul 2006
Location: Chesapeake Region and Maine
Boat: 42' Bob Perry sloop
Posts: 4,047
Images: 4

Maybe we could be of more assistance if we knew more about your boat and the specific setup, e.g.,

1. type and size of boat;
2. size of house bank and type of batteries;
3. type and size of alternator and whether internal or external regulator;
4. type and size of battery charger; and
5. type of service intended (weekend sailing, long-term cruising, etc.).

All these factors are relevant to decisions about charging systems.

The preferred configuration these days is for an alternator with an external regulator with the alternator output connected directly to the house battery bank (only), with an appropriate fuse or breaker in-line near the battery bank. The starter battery could be efficiently and automatically handled with an EchoCharge device, which bleeds off a bit of the current from the house batteries as needed whenever it senses a charging voltage on them. This arrangement is completely automatic and avoids all manual battery switching --less chance to make potentially serious and costly mistakes.

btrayfors is offline   Reply With Quote
Old 31-03-2010, 11:09   #6
Registered User
Strygaldwir's Avatar

Join Date: Dec 2004
Location: Deale, Maryland
Boat: SeaView - Privilege 37
Posts: 1,020
Images: 5
Sounds like the problem I faced when switching from the 3GM30 to the 3YM30.
Strygaldwir is offline   Reply With Quote
Old 04-04-2010, 15:09   #7
Commercial Member
CharlieJ's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: St. Petersburg, FL
Boat: Gulfstar Long Range Trawler; 53'; BearBoat
Posts: 997
btrayfors nailed it in Post #5: +1


Charlie Johnson
JTB Marine Corporation
"The Devil is in the details and so is salvation."
CharlieJ is offline   Reply With Quote


Thread Tools Search this Thread
Search this Thread:

Advanced Search
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

Similar Threads
Thread Thread Starter Forum Replies Last Post
Batteries Not Holding a Charge oldcatsailor Electrical: Batteries, Generators & Solar 6 11-01-2010 13:14
Best Batteries for Solar Charge Bash Electrical: Batteries, Generators & Solar 5 08-09-2009 08:53
Question About Float Charge for AGM Batteries s/v Jedi Electrical: Batteries, Generators & Solar 3 19-08-2009 10:46
Wiring House Bank - Your Input? bobfnbw Electrical: Batteries, Generators & Solar 15 11-05-2009 14:03
Batteries No Holding a Charge alanperry Electrical: Batteries, Generators & Solar 11 18-09-2006 10:16

Advertise Here

All times are GMT -7. The time now is 19:57.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.