If powering off of 12 volts I would use a power inverter to take 12VDC and make 120VAC and then use the proper power supply that came with the laptop and power through that to power the laptop. I would not power directly off of a 12V car battery etc.
Look at bottom of your laptop and see what the voltage and amp rating is if your looking to power it and dont have a power supply for it. I would only use Lenovo power supply of correct voltage and same amp rating. If you go with a lesser amp rating power supply on the Lenovo laptops they can detect this and run underclocked (slower). I have a Core i5 that has a wrong power supply for it of correct voltage but amp/watt rating is lesser than spec. It can detect this and so it runs at underclock with the wrong power supply.
