Hard disk replacement - battery removal required?

If you take your computer apart without removing the power source you risk destroying your logic board. It won't happen every time as is evident from nicks answer but it CAN happen. I personally would not take the risk of a very expensive repair. My advice is remove the battery--it was included in the guide for a reason. Good luck. Ralph

According to the Apple user guide for replacing the hard drive, they don't mention taking out the battery - probably why the battery screws are of the less common tri-wing screw. Even though you're trying to prevent a potential shorting of the logic board while taking out the hard drive, you are also risking a short by trying to take out the battery (which seems the same difficulty as taking out the hard drive).

Since I can't find the tri-wing screwdriver, and the Apple manual doesn't say to take out the battery, I will just be careful taking out the hard drive.

Not cutting off battery power has the potential to do damage, so it may be a good idea to disconnect it as a precaution. Just keep in mind you will lose your WiFi settings and time, but that's better then a bad motherboard.

I've done this with a T8 before in a pinch, but it can damage the screw. You will want to use a Tri-Wing Y1 if you want to remove and replace the battery.

As to the hard drive it sounds like the drive is on the way out. Take a backup while you have a chance and replace it. In some cases it's filesystem damage since the HFS filesystem doesn't seem as robust as it could be so you may be able to get away with a filesystem and permissions fix. Do not count on this, but also do not be afraid to try fixing it with something like DiskWarrior. Worst cases, you have to reinstall OS X. Repeated issues are likely to be a bad hard drive.

i bought a hard drive from here on ifixit... the seagate momentus 750 gig/ 7200, and the screws for the battery have five points, not three!?! i also had missing mounting screws that i replaced from a local apple store (luckily they has a few in back)... at any rate, i tried to install the OS (snow leopard) by booting holding down option as i powered up with the new drive (not removing the battery, since the tool kit i ordered only had torx and tri point tips)... my question is why won't the drive from ifixit show in an option button boot up, and why wont the boot from cd go any further that the opening sound and apple screen? any one else have this issue?

I did the same in my dell laptop while cleaning its work but when i turn it on again my laptop shorted on ssd part %#*@ never do that….without unplugging the battery…..