Originally Posted by
the evil twin
Battery gassing is usually due to overcharging.
I would check the Solar Reg and Battery Volts on the cranker.
If the voltage is constantly above about 14.2 out of the Reg or the Cranker is stuffed then that is the problem.
That would explain why it is worst in the arvo IE after a day of full sun and max panel output.
Also if you are doing two or more batteries off 1 Reg sometimes a failed battery will trick the Reg to stay at full charging rate and not switch to float charge which will stuff the good battery