The Panasonic EY9L51B 18V 4.2Ah Lithium-ion (Li-ion) battery incorporates all of Panasonic's latest battery technology, making the EY9L51B a market leading power tool battery. The 4.2Ah battery stores even more power than the 3Ah, making your Panasonic tools last as long as you do and more.
The EY9L51B uses Panasonic's propriety technology "Panasonic Solid Solution" (PSS) for dissolving and hardening key battery component substances such as cobalt and nickel, dramatically improves safety and provides exceptional reliability and a high output that is unique to cobalt chemistry.
Individual monitoring of each battery cell to ensure discharge control and to protect the EY9L51B from both overcharging and over-discharging.
It is possible to over-discharge a Li-ion battery and therefore damage its future performance in the process. Using a sensor to detect low voltage levels the EY9L51B built-in system cuts power to the motor when a minimum level is reached and a warning light flashes on the tool's control panel.
The service life of batteries can be degraded during heavy use by high temperatures created by rapid discharge. The Panasonic EY9L51B Li-ion battery features a sensor that like the above system, cuts power to the motor when a limit is reached. This will prolong life and performance of the EY9L51B battery pack.