Checking a Dead Battery - 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 08-05-2000
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
Checking a Dead Battery

After sitting through the winter season, our 320 (which is only two years old) won't start on battery #1. It starts fine on battery #2 and on BOTH. Battery #1 is reading fully charged as is #2. Any hints or suggestions before we resort to a costly inspection?
Peter and Mary

Tom Wood responds:

Dear Peter and Mary,

Electrical detective work can be fun. The only thing that can be deduced from your description is that there is nothing wrong with the starter. We don't even know whether the batteries are wet, gel, or AGM.

Get a voltmeter—if you don't have one on board, you need one anyway. A digital voltmeter is nice, but a simple analog cheapie will suffice for light work. Turn on your battery charger and check the voltage at the battery terminals while they are charging—it should be between 14.0 and 14.4 volts. If not, your charger has malfunctioned on bank #1, causing your dead battery. Shut off the charger, start the engine, and test your alternator output in the same manner. If battery #1 doesn't show any charge and you have a diode (splitter) in your alternator output line, the diode may be fried, requiring replacement and some more detective work to find out what caused it to fail.

If all is well at this point, charge both batteries fully and put on your Sherlock Holmes hat. Let the batteries stand for at least eight hours after they have finished charging, then test the voltage on both again—it should be between 12.8 and 13.0 volts. If battery #1 has fallen off in voltage, it is probably damaged beyond repair—replace it.

If both batteries test well, set the battery switch on #1 and test the voltage on the common output terminal of the battery switch and again at the starter. If these tests show a voltage drop, start checking all the wiring and connections, both positive and negative, from the battery to the switch, the starter, and to ground. Clean and tighten these connections.  It is even possible that the battery switch has failed.

Batteries on boats can, and very often do, fail in a two-year span due to sulfation. Unless the boat is used very often, or has a good quality three-stage shore-power charger, or has solar or wind chargers keeping the voltage up, two years is about all you can expect from most batteries. See Don Casey's article, A Little Help from the Sun.

Tom Wood

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 08:44 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) LLC 2000-2012

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