What solar controller?

[Stealaway]

I think the others have beaten me to it because the symptoms suggest dead batteries. After a day of sun you should be seeing something around 13.8 volts in my experience.

My problem seems to be the complete oposite

My batteries are going up to 14.9V both the start battery or the leisures at different times.
It only happens on very bright days during the winter. Throughout the summer obviously we are using them daily and I never see a problem.
I have even replaced the controller recently but its made no difference.
What voltage would be considered the maximum float voltage? - what's the problem?

 

[DBK]

I see around the 13.8 volts mentioned in my post. At this point the charging current will be very small and typically zero.

 

[Stealaway]

This could be useful.

https://www.emarineinc.com/Batteries-Maintenance-101

See also PDF

 

[DBK]

I don't know why you are seeing 14.9 volts. But is it heavily charging when you see these voltages? I guess if the batteries are failing the controller will increase the voltage if the batteries keep accepting the amps. In other words they never get to a state where the charger switches to a float mode.