Trolling batteries and on board charger question

[rned]

I have 2 AGM batteries for my 24 volt trolling motor and a 12v volt starting battery. I have a Cabelas Pro series 20 three bank charger. I started having trouble last fall with my batteries for the trolling motor not lasting as long as they had been. One day last fall I drained both batteries by 110am. I thought it may have been due to a little ore wind than usual. I pulled the trolling batteries and had them tested and was told they were ok. The garage told me to leave them on 2 amp charge that the batteries need a longer charge if they are really drained. Did that last year by using two automatic chargers and they seemed better. At the end of the season I pulled the batteries and moved them inside for the winter. I rotated a 2 amp automatic charger from one batter to the next every couple of weeks. Used them last week for several hours and they seemed ok. I plugged in the cabelas charger at the end of the day and left it on for a week. I went fishing Friday and the batteries only lasted about 2 hours.
Where do I start first in trying to solve the problem. I am thinking the charger is the problem since the batteries lasted ok the first week I went fishing when I used a 2 amp charger.

Both the batteries and charger are 2 years old. I troll .8 to .9 mph and I always have the charger plugged in when I am not fishing.

Thanks

 

[T_Herrod]

Re: Trolling batteries and on board charger question

Could be that the charger is over charging the batteries.

 

[gm280]

Re: Trolling batteries and on board charger question

If you have the ability and the capability, install an amp meter in line with each battery (one at a time would be ok) and measure what current the battery charger is outputting. Do the same with the other battery. Also measure the voltage across each battery before and during their charging cycle. If the voltage isn't increasing when you apply the charger, look for a new charger. Then depending on the current reads you read, you can figure out if the batteries are getting a full charge or not...

 

[bruceb58]

Re: Trolling batteries and on board charger question

Next time you charge your batteries with your charger, monitor the battery voltage. When the charging starts, it will start increasing until it gets to around 14.5V. Once the battery is charged, it will go into a float mode of around 13.4V.

Don't ever discharge you batteries past 12.0V which is around the 50% point. Doing so repeatedly will destroy your batteries.