The KRESS 20V Max 6A Rapid charger will charge your KRESS KROSSPACK® 4.0Ah Battery in 45 minutes, and a KRESS KROSSPACK® 20V Max 6.0Ah Battery in 65 minutes. It includes built in intelligence which protects against over/under-voltage, maximizes charging & discharging current, & operating temperature range. The Air cooling function is for active temperature management, effectively reducing charging temperature, equalizing charger temperature, & prolonging charger life. It features 4 x battery charging indicators, providing charging status, temperature overload or battery issue.