If I install a drive caddy in place of my optical drive how will the battery fare?

I ordered my sager and an ssd to replace the hdd, and a caddy.
I'm planning on installing my ssd as the main drive, and a hard drive caddy in place of my optical drive with my 750gb hdd. Will the hdd constantly be running and drawing battery? or will it be off unless i access it?

Also, when I install two more sticks of 4gb ram into my laptop does it matter whether i go with 1.35V or 1.5V?

 

The HDD should power down when not in use, only spinning up with you're actively trying to access it (either you personally or the OS/programs). The RAM won't make that much of a difference; the display, GPU, motherboard, and CPU will suck up a lot more power, relative to RAM.

 

Depends on your power settings. You can allow the disk to spin down after an allocated amount of time.

The .15 V will not make a noticeable difference in performance nor battery power consumption.


More or less just reaffirming what Kuroi-Tsubasa said.

 

I mean, at most you might have a time delta of maybe a few minutes with the RAM differences, and maybe 15-20 minutes (roughly... just guesstimating here) if you leave the HDD spinning when not in use.

You'll get a much bigger time delta if you lower your display brightness a few notches, or disabling dGPU and only using the iGPU (if possible on your laptop).

 

Theoretically, you will increase your idle wattage by about 1w as this is what most hdds idle at. However, since it isn't a system drove, there aren't constant background interrupts so the drive may idle even lower as per power saving scheme.
As for the ram, it makes a difference proportional to your battery life under load. Idle life isn't affected so much due to ivy bridges superb memory io idle power gating.