It is safe to leave slide pack batteries charging for the entire cutting season, because they have an internal time and cannot be overcharged.
After the cutting season, our recommendation for NiCad packs is to store them indoors in a location between five degrees Celsius and 25 degrees Celsius, or between 41 and 77 degrees Fahrenheit.
After the last use of the product of the season, take the batteries off the product and store them off the charger in the temperature range mentioned above.
The batteries do not have to be charged up before storage, and can be stored at any level of charge. Simply store them after the last usage.