RangeRoller dt said:

13.8 was what I was getting off the old one. Which was correct for its original set point and why I originally didn’t think anything was wrong.

Click to expand...

13.8v was the original set point and was fine 20 odd years ago with old lead cell battery's ,but battery technology has moved on and you really need 14.4 or better to get there juices stirring and battery longevity ,modern battery's will fail sooner and not last as long at the 13.8 set point ..

14.8v is the ideal charge voltage for calcium batteries, which dont last long if not charged with at least 14.4v
not all modern lead acid batteries contain calcium
edit: the max recommended for older/normal lead acid is 14.4v