Checking the battery status from the terminal using UPower tool.
$ upower -i /org/freedesktop/UPower/devices/battery_BAT0 | grep -E "state|to\ full|percentage" state: charging time to full: 4.2 hours percentage: 28.1695%
As shown above, the new battery need 4.2 hours for a full charged. Rather long compare to the non-original battery which only need 1.5 hours. Why the difference? No idea what so ever.
To extend your battery life, it best not to hold full charge for a long period of time and keep the battery in 40% to 80% charged range. Unfortunately, my beloved E420, sadly is not a real Thinkpad does not (shown below) has Tp smapi support which can regulate battery charging within the threshold range.
$ sudo apt-get install tp-smapi-dkms $ sudo modprobe tp_smapi ERROR: could not insert 'tp_smapi': No such device or address
How then ? The only best way to extend the battery life is remove it when not using and keep your laptop temperature cool. Or alternative, write a script to monitor your battery charging within this range and notify you when to start and stop charging.