How does Turbo Boost Technology impact battery life expectancy?

[B@Ts]

When running a T9900 in a laptop on battery, the power draw is 'relatively' constant, making the drain relatively constant (assuming no DVD is read and SSD is in place). This - I guess - is better for the life expectancy of the battery.

When running a i7 850QM with Turbo Boost Technology, the power draw is less constant, given cores are switched on/off (using same assumptions as before). This - I guess - is not in favor of the battery life expectancy, right?

So when selecting between a T9900 (or T9600) and a Core i7 850QM ... which would be the better choice??

P.S. - By battery life expectancy, I refer to the number of times one can recharge the battery, NOT how long the battery lasts on 1 charge (on average).

 

[cjl]

What makes you think a T9900 has relatively constant power draw? It will vary hugely from idle to full load, with changing clock speeds, voltages, and usage. If you don't believe this, compare the battery life of a notebook running Prime95 to one sitting idle. The i7 architecture will also vary hugely from idle to full load. In both cases though, the total draw of the notebook should come to roughly the same levels (plus or minus a few watts).

As for the total battery lifetime expectancy, this is mostly dependent on how fast it is discharged. Lithium batteries tend to last longer if they are discharged more slowly. In the case of the i7 vs Core 2, I would expect the overall battery lifetime to be roughly the same in both cases.

 

[B@Ts]

What makes you think a T9900 has relatively constant power draw?

Thanks cjl.

I didn't want to imply it has a "constant" draw, hence the "relative" term in the phrase.

I was under the impression that with the T9900 or T9600 the 'raw force' is always available, hence the power draw is relatively more constant compared to the Turbo Boost Technology, which increases power draw fluctuations.

I'm debating on which processor I'd like to get for a new laptop (obviously with a 9-cell battery, hoping it will last me longer then 2 or 3 hours). Reading up on the T9900, battery (SHOULD) last up to 3 hours ... but again, it is more about the battery life expectancy (even if I'll be getting a backup 9-cell battery anyway).

 

[cjl]

The Core 2 CPUs do a fairly large amount of power management, and their power draw can range (in the case of the T9900) from a few watts up to over 30.

Honestly, at this point, I'd get the i7. It's a good bit faster in just about every task, and as I said, it shouldn't have an impact on overall battery lifetime. It may affect how long the computer can run on a charge (depending on your usage), but it shouldn't draw nearly enough to make any difference in the number of charge cycles. Typically, lithium batteries aren't negatively affected by power draw until at least a 2C load, meaning a load that would completely drain the batteries in half an hour (a 1C load drains the batteries in 1 hour, a 5C load drains the batteries in 1/5 of an hour, etc). Some batteries rated for high drain can even be OK with a 10C load without any significant impact on battery health. As long as you aren't drawing that much power, you should be fine.

 

[B@Ts]

Thanks for the info. This actually persuades me (gives me a bit of an excuse) to go for the newer version of the laptop in the end ...