Switching Batteries - 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 > Contributing Authors > Gear and Maintenance Articles
 Not a Member? 

Closed Thread
LinkBack Thread Tools
Old 04-10-2002
Contributing Authors
Join Date: Jan 2000
Posts: 266
Thanks: 0
Thanked 10 Times in 7 Posts
Rep Power: 16
Tom Wood is on a distinguished road
Switching Batteries

Is it true that I shouldn't change my battery switch when the engine or dockside charger is running?

Tom Wood responds:
Thanks for your question. The answer depends on where your battery switch is at the time. I am unaware of any battery switch that would not allow you to change from "Battery 1" to "Battery 2" or to "Both" while the engine is running. However, most switches can never be turned to "Off" when the engine is running without instant failure of the diode trio inside the alternator. And it is easy to make a mistake and turn the switch the wrong way, so some sailors just have one simple ruleónever touch the
switch when the alternator is turning.

There are battery switches available with an "Alternator Field Disconnect" (AFD) circuit built in that can overcome this problem. The field wire to the alternator is led through the battery switch, and is automatically disconnected when the "Off" position is chosen. This protects against the captain and crew members accidentally switching to "Off" when they thought they were switching to "Both." These switches look outwardly the same as your current one, and only cost a few dollars more. The installation is identical except for the running of the alternator field wire to the switch.

Another alternative would be to add a battery combiner or isolating diode in the alternator's output circuit. This would eliminate the need to be concerned with the charging process at all when the engine is running.

Your battery charger question will depend on the charger. If it has one output that is wired to the common terminal of the battery switch, you would need to read the charger's manual to decide how much charging capacity it has. If it has two independent outputs already wired to each battery bank, the position of the battery switch is irrelevant. Here's hoping this answers your question.



Quick reply to this message
Closed Thread

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

All times are GMT -4. The time now is 07:55 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.