Help With Battery Charging

[Avery Gilliland2]

My new battery charger is showing full charged but it appears both trolling batteries are near death. My trolling motor will run just for a few seconds and then start pulsating and then completely stop. I can let it rest and then it does the same thing. Is the charger bad along with the batteries or if I replace the batteries will the charger actually fully charge my batteries. The charger is new the past fall. Thanks for the help guys. Gilly

 

[Marty Klein]

You forgot to mention the COA that reads -- trolling motor bad. Hard to help from afar, but all three COAs are possible. You need to have the batteries checked to determine if they are bad. Same with the charger. I think for the charger you can just throw it in contact with a volt meter and see if you're getting 12 out of the leads. The batteries I think need to be professionally tested. How does the trolling motor run when the charger is hooked up? If it is running fine, then I would say the batteries are the issue.

 

[Avery Gilliland2]

tested the TM with the charger plugged in and it ran great. Unplugged the charger and the TM barely turned. Must be the batteries. I will test the charger leads with the volt meter just in case. Thanks for your help Marty. Gilly

 

[Dennis O'Byrne]

Put a volt meter on the battery with the trolling motor connected. Check the battery voltage with the trolling motor off and then again with the motor on. Often, the voltage on a bad battery will look correct but the voltage will collapse when the load is applied. I'm betting that when you turn the motor on, the voltage will drop drastically.

 

[Marty Klein]

dpo51: Am I correct in saying that test you describe will give the same result as the test they do at the mechanics?

 

[Dennis O'Byrne]

Marty, it will effectively tell you the same thing as the mechanic would. The key is testing the battery under load and see if the charge stays up. A mechanic will probably test the specific gravity also but the load test should tell you all you need to know. A fully charged battery with no load should read around 14+ volts. Under load, it will drop. It should not drop under 12v under any circumstances (A really good one should stay over 13v.). If it does, there is a real possibility that the battery has lost its capacity and will need to be replaced. It is a possibility that the trolling motor is bad but that can be checked by temporarily connecting it the starting battery and testing its operation. Just for giggles, you may want to check all of the connections also.

 

[Mike Clayton]

So my batteries after charging hold around 12.5, is that a sign they are are going south??

Mike