depends on what batteries you're using. all chargers have a voltage cutoff, some are adjustable and some aren't. the chargers without the adjustable cutoff have the voltage cutoff set at the factory by way of the specified charging parameters engineered into the electronics of the charger. if you're using newer cells, it's a good idea to get a charger with and adjustable cutoff. also, if you're like me and have some ancient cells, the adjustable cutoff us usefull to be sure you get enough juice on those old nicd 1700's
. hope that answered your question.