Probably a great time for many of us to pay attention to our Odyssey PC545s. On the cusp of spring in the northern hemisphere and lots of our precious V11 have languished for other reasons keeping us home. Last night during a severe storm watch, I decided to bring an Anker PowerCore battery pack up about 20% using the ten year old PC545 in my test bed, Swampee the Cub Cadet. This battery was in the Sport almost five years, then stepped down into the tractor nearly five more. At some point in the last couple years, I found it under 8 volts and brought it back using these methods.
After the Anker charged, I was surprised to find the PC545 at 12.43volts . . . ("That's ded, Jim.") A little research and I discover the PC545 is 13Ah capacity and the Anker (6 x 18650 Li battery pack) is 20.1 Ah! Woops . . . Seems I used the old PC545 to statically charge a battery with 50% more capacity.
The EnerSys charger would not set a deep charge after two discharge cycles. I've seen this before: a rather deeply discharged PC545 (below the 12.65v charging threshold) quickly (under a couple minutes) switches to "float" charge on the EnerSys and then stays below the AGM float voltage (13.5-13.8v). Then, as soon as load is applied, the battery would drop back to it's pre-charge state. i.e. - Not taking a charge.
Recovery method: applied 6 amp charge, manual/constant, until 15.0 volts was reached (35 minutes). Now to monitor how long it takes to statically discharge to the 12.65v charge threshold. If it takes less than 24-48 hours, I'll repeat the discharge/charge to 15.0v until it either holds for days to weeks, or have to declare the ten year old PC545 "done" at which point the Sport gets a fresh one.
Once again, the PC545 is awesome using the correct methods.