Do I need a new solar controller?

[john61ct]

Even the top quality SoC monitors - frequently calibrated by the owner - are only within say 4% accurate at best.

It is **your** job to tell the **meter** when the bank is at your definition of 100%. As per endAmps spec at Float transition.

If not every (other) cycle, as often as convenient.

That is required for it to do its job, being accurate in the mid ranges, to help you avoid discharging too deep.