So my original battery in my Macbook Pro (MC723LL/A) passed 1000 cycles a few weeks ago, and the battery life has been getting horrible. I ordered a new battery off Amazon (A1386, same as factory). When I installed the battery and booted up, however, the computer was running REALLY slow. I opened Activity Monitor, and kernel_task was using between 200 and 300% CPU, and there were several Google Chrome Helper tasks using huge amounts of memory/CPU as well. At first I didn't realize what had happened, and spent quite awhile trying to debug and sort out the problem. Finally out of frustration I switched the old battery back in, and voila, everything was back to normal. What could possibly be causing this?? Before you suggest it, yes I tried PRAM/SMC resets, of course I rebooted the computer numerous times, repaired permissions, ran a full sweep with OnyX, deleted and fresh installed Chrome, etc, etc.