Diagnose my battery problem

[ksbhjohnson]

I am having a battery issue and cannot figure it out. The boat is a 17' I/O 4cyl 3.0l. Earlier this season my boat would not turn over, a jump box was used and it fired right up. Figuring the battery was bad, I took it to the auto parts store and they tested it and said it was just fine so I put the battery back in the boat. The battery is an Interstate deep cycle marine battery. I noticed that if it sat for more than a couple of days without being started, it will not even attempt to turn the motor over. However, once started with a jump box I can shut it off and fire it right back for the entire day on the water with no problems. Also, there is enough battery to run the blower, radio, outdrive lift, etc. just not enough to crank the motor. I thought that I had something creating a slow drain on the battery, so I installed a battery switch on it to eliminate the possibility of a slow draw. Unfortunately that did not work either and the battery still behaves the same as it did prior to the switch being installed. Any ideas?

 

[spdracr39]

Re: Diagnose my battery problem

What is the battery voltage when it won't crank? Your issue could be corroded or loose connections but a battery can have good cranking amps when fully charged and not have the ability to hold a charge. Clean and tighten all your connections. If that doesn't fix it take it back and let them test it then let it sit a couple of days and test it again.

 

[Barnacle_Bill]

Re: Diagnose my battery problem

Have the battery load tested.

 

[Silvertip]

Re: Diagnose my battery problem

Using a jump box you connect essentially eliminate the connection between the battery cable terminal and post of the starting battery so the engine starts from the jump box. Without the box, the engine must again rely on the connection between the battery cable terminal and the post on the battery. If that connection is corroded or loose it cannot pass current and the engine won't start. Clean and tighten the battery posts and the battery cable terminal ends. Then connect and tighten them securely. Remember, both the POS and NEG cables must be clean and tight on the engine end as well.

 

[generator12]

Re: Diagnose my battery problem

In no particular order:

1. High resistance connections at the battery, possibly including the connections between the lugs and the wires
2. Leakage across the face of the battery. Make sure it's clean
3. Something remains connected when the switch is opened
4. The test result was wrong and the battery is actually bad

 

[Auger01]

Re: Diagnose my battery problem

Sometimes a starter solenoid that is going bad will exhibit the symptoms you describe.

A quick round troubleshooting with a voltmeter should determine the cause of your problem. Do you have a voltmeter and know how to use it?