I have Minn Kota 4 bank Charger and 4 Optima Blue Tops. Batteries are 3 years old, Charger is 5 years old.

The Last time I used the boat, my batteries felt a little weak on the trolling motor.

When I plugged the charger in I had a red light on Bank 3 that said to check connection. So I checked and cleaned all connections with no change. Was late at night so I just left.

Went back yesterday thinking I possibly had a bad battery. So I swapped the Bank 3 and Bank 4 leads on batteries 3 and 4.

So now with Bank 4 connected to Battery 3, I get a green light stating battery is fully charged.

Now with Bank 3 connected to Battery 4, I get the red light saying to check connection.


So initially the first thing that came to mind is my batteries are fine, I have a bad bank on my charger.

But I find it really strange that battery number 3 was fully charged after being connected to bank 3, that I think may be bad.

Connections are all good, Fuses are Good.

Any ideas?

Check the fuse and clean on that wire