A copy of the "Smart Battery, Smarter Power Pack" project. I had originally planned to modify his project to accept Lenovo batteries instead of the Dell batteries used in his project. This effort was hampered by the inability to find Lenovo laptop battery connectors. I found them.
Clockwise from top, we have the battery connector for the six-cell X250 battery, the "TE Connectivity 2mm pitch Battery Plug assy. 7Pos. H=4.0" connector that fits perfectly in the battery, and the newest Lenovo charger port. These are the parts necessary to build a Thinkpad battery power bank.
Quick overview of what this thing does: it's a small board that clips (or velcros - haven't decided yet) onto a battery, and provides a charging port through the usual Lenovo charger. 2 USB charging ports are also provided, allowing any phone or device to fast charge from the Lenovo battery.
There are exactly two functions to this device:
Recharges thinkpad batteries with the usual Lenovo charger