2 Chargers were connected to 4 Lead Acid 225Ah Truck-Starterbatteries.
After 4 years of service all 4 batteries are broken.
Discharging was never ever below 12V
I assume that the problem is with trickle charging as lead acid's shall be charged with 14,8V with a bulk(trickle) charging of 13,4V to avoid sulfating.
In fact the Blue Solar Duo chargers can only be set to 14,8/13,7V which is, to my opinion, to much and results in continous charging and by the years continous sulfating with the a.m. breakdown.
OK Truck-Starter batteries were the wrong decision but I think this is not the real problem and obviously I want to avoid the same problem with my new Trojan T125 which are said to need 13,5V bulk-charging.
Though I am very glad for every input that helps me out of this mess.