The new 5.0 Ah 18 V Bosch FatPack battery (BAT621) offers 25% more runtime (compared to Bosch 4.0 Ah) and more than 65% more runtime (compared to 3.0 Ah). CoolPack Design technology, including advanced heat conductive housing, keeps the battery cooler for 2X longer recharge life. Check the charge status quickly and easily using the integrated fuel gauge. These batteries are designed to work as hard as you, so working in cold weather down to -4°F is no issue. The BAT621 is compatible with all Bosch 18 V Lithium-Ion power tools, radios and more.
Maximum run time - 25% more run time (compared to Bosch 4.0 Ah)
Unique CoolPack Design - advanced heat conductive housing keeps battery cooler lives up to 2x longer
Integrated fuel gauge - for fast and easy charge status
Cold weather operation - battery will work down to -4°F
Durable housing - survives 3 m drop
Flexible Power System™ - works with all Bosch 18 V Lithium-Ion tools