Hi wa8yxm,
Actually "dancing on the needles" is not science. It is an art form. The method that works for a 3 month old battery with 15 cycles would not be ideal for a 3 year old battery with 180 cycles.
If I understand correctly, the 3 month battery may need lower voltage (14.8) and a different time frame to recharge than the 3 year old one. The three year old one may almost certainly have greater internal resistance. That means tweaking the voltage a bit higher. How much higher? Ask four experts and you might get 12 answers.
Does anyone know the frequency of replacement of large "back up" battery banks such as those used by telco's?
