Should my MPPT controller drop to 0 amps coming in, from solar panels only, for a few seconds before building back up to 16 amps or so, depending on the sun, stay there for a minute or so & then drop back to 0 amps for a few seconds again & repeat this cycle?

Is this normal behaviour?

I have a 60A Mppt Controller; 550W Solar Panels; 780Ah (6 x 130A) batteries.

I only started watching what happens because I'm not getting fully charged batteries recently. The batteries have always been fully charged when running fridge & freezer 24/7 until recently. I have disconnected the freezer last week & fridge today to try & isolate the fault.

I'm pretty sure it's not the controller as I just bought a new one because the previous Mppt controller did the same but worse - it was 40A & not big enough.

I've pulled all the batteries out to check individually & they all have exactly the same voltage.

I'll be checking what amps the fridge is drawing next week & checking if something is remaining "on" that shouldn't.

It's got me beat!!

TIA
Larry