I replaced my starting battery with an AGM several months ago. This week I turned on my LED cabin lights for the first time with new battery. Now my cabin lights are flickering. I wonder if I need on isolator on my power feed to the switch panel. Never had any issues with a flooded wet cell.

Is the battery charged? That would be the first thing to check. Electricity doesn’t care what type of battery it is. If fully charged then check connections for corrosion

Yep, fully charged and absolutely no corrosion. I first noticed the console lights flickering and thought it was just a problem with them but then I turned on the light on front deck and they started to also flicker. Never had this happen with flooded cell batteries. I meant to test this morning without motor running but forgot to when I covered the boat. I know of people that have had issues with AGMs fully charging on their vehicles.

If the battery is charged then you need to clean all connections. Depending on how old the boat is some of the wiring may have corroded under the insulation

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check ground first, make sure all connections are clean and tight. if it is while the engine is running check your charge system on the engine, clean and tighten.

You guys got me thinking. Not always a good thing but might be in this case. The ground wire for my switch panel is on a terminal connector on the batterry post. Even with the previous battery I had issues finding a connector that would tighten to my liking. It is snug but I can twist it off my hand. Looking at some terminal connectors I found out that posts have 2 sizes. 19mm and 17mm. Positive side is good and tight. I have another connector that tightens down to 5/8" which is slightly less then 17mm. I will try it today. The cable to the motor is not on the same connector and it is good and tight. I cleaned all the wires when I changed batteries as I alway do.

I’m running three AGM’s 2 for the 24v trolling motor and one for the boat , motor and graphs. I have LED lights and bulbs in just about everything. It’s not the Battery. You have a ground issue I would say.

I have a MinnKota alternator charger and I think it is causing the LEDs to flicker. The alternator charger charges my wet cell TM batteries while running after the cranking batterry reaches full charge. It does a good job. I ran from the dam to the bridge on Tawok today and the batteries gained 25% charge on the monitor. I am going to switch to lithium for the TM batteries next year so the alternator charger will come out.