Minn Kota charger questions

About two weeks ago I installed a 3 bank Minn Kota charger and 3 new optima 31 agm batteries. Took the boat out the other day for the first time, went to plug the charger in today and the starting motor went from 25% to 75% in five hours. The two trolling motor batteries are still at 25% after 5 hours of charging. I didn’t run the batteries completely dead when we took the boat out the other day so it seems odd it’s taking so long to charge them. I’m using a 10 gauge extension cord that’s 25’ long, all the inline fuses are good, and the master switch for both sets of batteries is off so nothing is drawing power.

Are my expectations that these batteries should charge to 100% in 8ish hours way off, or could something be up?

If my expectation are off, how long should it take for the Minn Kota to charge them up?

Thanks for the info!

Charger hooked directly to batteries? Charger set to charge AGM or conventional batteries?

How many amps per bank is the charger? Model #??

The trolling motor batteries are only at 25%? How dead were they before you started charging them? Were they fully charged before you launched the boat? Are they in parallel or series? Check actual voltage, not charge percentage, at each battery with a multimeter.

I switched to AGM batteries last year and it seemed it took longer for them to charge and was told that it would.

Sounds like they were pretty low to begin with, and depending on what model you have and it’s output it can take awhile to get them back to good.