Till yesterday, after the firmware upgrade the batteries weren't charged correctly. The app showed that they charged in a couple of hours to their full capacity. Obviously they discharged as fast as they charged. The app didn't show the correct state of the batteries.
Today I have set the lower discharge limit to 0 and the maximum charge limit to 100.
The battery charged till 99% in few time, but they took very long time to reach 100%. I suppose that all my two batteries reached their real full capacity after 4 hours or so, of full sun. Now, at night they are discharging as they should. I suppose that the problem is the app then the firmware.