Draper's Storm Force 20V Charger and 20V Fast Charger are compatible with their 20V Interchange range of batteries. These are used by most of the storm force range and allow you to use a wide range of powerful, practical tools with the same battery and charger set-up.Compatible with 20V Interchange batteries1 hour or less charging timesWorks with 2.0AH and 4.0AH batteriesDraper's Storm Force power-tools range use state of the Lithium Ion batteries to provide big 20V power. Lithium batteries are terrific in a lot of ways. Lightweight, long-lasting, able to survive thousands of charge cycles. They do have more technology in them than older Nickel-Cadmium or Lead-Acid batteries however. This technology helps regulate the voltage stored in the battery and how quickly it is charged or discharged. In order to get the best out of them it's important to use the right kind of charger that is compatible with the onboard electronics.The wrong charger can either fail to charge the battery altogether or not charge at the right rate causing battery damage.These chargers from Draper are designed to work with the 20V Interchange range of batteries, ensuring the batteries stay healthy for as long a useful lifespan as possible.Draper are quoting around an hour for the standard unit to charge the 4.0AH battery and around 45 minutes for the super fast charger to charge the same battery.