I have a constant current charger for my 9V 300Mah batteries. It uses approximately 40ma of current. I use a wall transformer designed for 12Vdc output. If I charge the 9v battery from dead at a constant current rate of 40ma, I usually do it for between 9 and 10 hrs. The full Mah of the battery rating plus 25%. My question is, what about the voltage of the charging supply? Currently the 12Vdc wall transformer has a no load voltage of 17.5Vdc. Does it make any difference? I know if the input voltage is too low, then the constant current source cannot maintain the constant current. Can the input voltage be too high? I would think so.
Thanks
Thanks