I am using a MPPT 75|15 SmartSolar to load a 24V AGM-Battery-Grid on a small Sailing Boat.
Battery: 2 x 75 Ah 12V AGM Lead Battery in serial. With 2A Balancer
Solar Panel: 2 x 50 Wp in serial. OCV 43V; MPPV 37V
I proofed fuse and every connector. Each module reaches the OCV with ~20-21V seperately.
This setup worked perfect for 4 years.
Due to a little damage at the boat I had to change the setup from 24V to 12V. The Solarpanel has not been changed to parallel. A 12V Ventilator was driven by the battery over the load-exit from the Solarcharger. This also worked perfectly for more than 5 weeks.
The boat is dry now and repaired. After switching back to 24V-setup (and changing the parameters in the App), the charger doesn't load the battery anymore.
Battery voltage ist at 25,2V but after connecting the modules to the charger the solar voltage is always 50 mV below battery voltage. I took care for a perfect sun-orientation and while I tried to charge the battery it was clear sky without clouds.
I checked the fuse (which was OK) and after re-inserting the fuse the solar voltage increased periodically up to 38.5V and dropped back to battery-voltage within seconds but not constantly and charging did not start.
Any ideas for this issue?
Thanks a lot for your support.