FOCUSTEC 48Wh 10.8V 6-cell laptop battery for ThinkPad E430 E431 E435 E440 E445 E530 E531 E535 E540 E545 B590

Replacement for ThinkPad E and B series

This 48Wh lithium-ion battery replaces the original 75+ six-cell pack used in ThinkPad E430, E431, E435, E440, E445, E530, E531, E535, E540, E545 and B590 models. It matches part numbers 45N1048, 45N1049, 45N1043 and 45N1042. The unit is new from the manufacturer and rated for up to 500 recharge cycles. It suits owners who need a direct swap for a worn or failed factory battery.

Fits existing chassis and power circuit

The pack uses the same 10.8V output and six-cell layout as the original, so it seats in the standard battery bay without adapters or cable changes. It draws charge from the existing AC adapter and communicates with the laptop's built-in fuel gauge. No BIOS update or driver install is required. Buyers who need a higher-capacity pack or a different voltage will not be served by this model.

Delivers steady output through a full discharge

Lithium-ion chemistry maintains a stable voltage curve during extended use, avoiding the sharp drop-off seen in aged cells. The 48Wh rating supports typical office workloads across a full workday on a single charge. Cycle-life testing targets 500 full recharges before capacity falls below useful levels. Users who routinely run sustained heavy loads such as rendering or compilation should expect shorter run times per cycle.