Hey I hope everyone is having a good day. I have a question I plugged my batteries in the other day with a minn Kota on board charger. And one of the batteries is still on a yellow light after 48 hours. Is that normal?

What size charger?  After 48 hours, almost any size charger should have charged the batteries.  Sounds like you probably have a bad battery.  If it's a battery with caps, check the water and feel the battery.  If battery is warm, you need to turn it off.  If not, check the voltage with a voltmeter across the battery terminals before you turn it off.  You should have at least 13.7-14.4 volts if the charger is working properly.   If in doubt about the charger, switch the charger cables between the batteries and see if the bank that shows ready will charge the one that's not.   Most likely that battery has either gotten hot or is junk or is both. 

Alright thanks for the reply I'll go do that

My Minn Kota Precision Charger (MK 345PC) sometimes had problems detecting my batteries and wouldn't charge them. I got the yellow light, too.

 

I read troubleshooting discussions on several forums and one of the easiest things to try was a better extension cord. It seems that Minn Kota Precision Chargers are sensitive to inadequate line voltage.

 

I replaced my long cord with a shorter, heavier gauge cord and the charger now works perfectly.

Alright thanks man I'll definitely give that a try