Canadian Rainbirds wrote:
I would suggest a higher capacity charger for those emergency moments. 1.25A will barely make a dent in big deeply discharged batteries. At a voltage of 12.9 it may not have reached it's maximum charge. Was the battery voltage still rising or did you just stop at 12.9? Normal charging with a smart charger is to take the battery up to at least 14.4 until the voltage stops rising. A float (maintaining) voltage is usually around 13.2 or so give or take a decimal or two.
I suspect the battery has reached or past it's "best before" date.
A hydrometer will tell you the real story.
or take the battery to auto parts store and have it load tested most do it for free But my guess is battery is beyond service life
