Nokia Battery BL-4D The Nokia Battery BL-4D is a lightweight, Li-ion battery that gives you 1200 mAh of power so you can stay in touch, stay online, and stay connected longer. Power to stay connected Accomplish more and get the most out of your phone with this long-lasting, lightweight Li-Ion BL-4D battery gives you 1200 mAh of power for extended use of your compatible Nokia device. For: Nokia E5 Nokia N97 mini