Battery dead, MacBook freezes during reinstall of Mac OS X

Hello

I was offered a MacBook Pro unibody from early 2011 with 2 GHz i7 QC processor.

The MB seems to be defect, as the battery is dead (must be exchanged, could not be recharged etc) and the MB freezes randomly during installation of Mac OS X.

Is it worth to buy? Is it only the battery which causes it to freeze, because the CPU is drawing more current during installation tasks and the battery cannot offer the additional current?

I am referring to Apples official guide to leave the battery in the MB everytime.

Regards, Stone