Does CPU speed drop when only on battery?

I'm not sure how you would expect to get 5-9 hours of battery life if this was not the case.

It's not so much that they drop the CPU speed when on battery, but instead it is dropped when your not doing anything intensive (for example, it probably isn't going very fast when your just browsing macrumors). From there, it will speed up to regular speed when under some strain, and then turbo boost will kick in and decide how much it can overclock based on the current environment (temp etc)

 

The CPU will downclock itself when not doing anything intensive, regardless of AC or battery power. For example, I have a 2.4GHz C2D MacBook, but that's just its max operating frequency, it normally runs at 1.6GHz under light load. The CPUs with turbo boost list the stock frequency as the highest frequency that will not be limited by heat or load, but it can either be higher or lower than that. It's not limited to a lower frequency on battery though.

 

A MBP does not cut it's computing power down just because you don't use the power adapter.
Some energy saving options like screen darkening, etc. will be preset, but it's not like with some Windows notebooks, which cut 50% power off the CPU to save battery energy.

These "up to 9h" statements are - let's say... theoretical conditions that can maybe reached by the user *cough*.

There are a lot of smart power saving options like the 2nd GPU, but they are enabled whether you use the power adapter or not. Energy efficient machines that don't steal your time by slowing themselves down if you need full power.

 

Yeah, like if I turn my screen/backlight all thew way down, turn off all my applications etc. i can potentially get my battery to last about 12 hours.... but sitting for 12 hours with nothing to do but watch the battery timer count down isnt that much fun...

 

Totally agree

 

As an ex Windows user I couldn't be more delighted with the battery life on my new MacBook Pro