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I waited to get Mountain Lion until the bugs got ironed out...

kfergiez

kfergiez

macrumors 6502
Original poster
Jul 5, 2010
276
1
Once the news hit about Mountain Lion, I though I'd wait until the battery issues have panned out. I hear that they've been ironed out, but you still lose and hour of battery life with Mountain Lion versus Lion.

How accurate is this information, and is it worth it with cost not being an issue?
 
Mainly I'm worried because of a few posts on this forum, but there are articles EVERYWHERE that include benchmarks. I just don't want to shorten my battery life. Even Lion took its toll.

The Mac Observer Article
 
RE: battery life and battery meter apps...

Hi,

Maybe this is "old hat" and obvious to you, but there have been a number of threads with people worrying about battery life readings and then using these readings to complain that they "lost 4 hours of battery life under ML", so...

... instead of just reading the "time left" on the various battery meter apps, you must actually use the machine until the battery runs out in order to measure the actual battery life. In other words, the "time left" readings are estimates that fluctuate all over the place depending upon what is happening on your computer over the last few minutes (it is based upon a running time average of power consumption, in other words). Watching the "time left" readings suddenly drop from 10:30 (10 hours 30 minutes) to 4:15 (4 hours 15 minutes) does not mean that your battery suddenly lost 60% of its stored energy, rather the algorithm that provides the "time left" estimates updated the "time left" reading based upon your current power usage.

So, if a Lion battery app tells you that you have 7:00 of "time left" when fully charged and you then upgrade to Mountain Lion and the ML battery app tells you have 5:00 of "time left" when fully charged --- this does not necessarily mean that you have lost two hours of battery life in going from Lion to ML. To actually determine if you have lost any battery life, you need to perform controlled experiments, first on Lion, then on ML, to check your actual battery life under both operating systems.

A controlled experiment is actually somewhat difficult to attain because of the complexity of operating systems and the various processes they automatically run. First of all, you would have to stop spotlight (or have the machine on for a number of hours so that spotlight indexing has finished) and then run a known program (that runs without stopping) with little other activity (i.e., don't run your web browser while this experiment is running, you just have to leave the computer alone and let the battery life experiment run by itself until the battery dies) until the battery is exhausted. Repeat the same experiment under Lion and ML and compare the battery life results.

Switon
 
kfergiez said:
Once the news hit about Mountain Lion, I though I'd wait until the battery issues have panned out. I hear that they've been ironed out, but you still lose and hour of battery life with Mountain Lion versus Lion.

How accurate is this information, and is it worth it with cost not being an issue?
Click to expand...

Here is what I found with my system……I recorded my actual working time on the system in a separate log after I noticed the change.

After the upgrade to ML my battery life went from:

6.5 - 7.0 hours >> 4.5 hours

(note: I quote the starting hours as a range as I had not timed that part exactly, as running under SL and then Lion it had not been an issue in the slightest and was just awesome battery time)

At this point I also tried a wipe and clean install, it made no difference.

After 10.8.1 upgrade:

4.5 hours >> 5.75 hours

An improvement, but still not where it was. I have also removed the Notification Centre as I was not using it anyway and reports by some people indicated that you might gain some battery life by disabling it.

My battery condition remains where it was when I started the upgrade process at 94 %, as reported by Coconut Battery.

In all cases I was using what I call day to day apps. i.e., Safari, Mail, TextEdit, Word, Pages - not what I would call a heavy workout.

As you can already see from the responses, not everyone had been affected in the same way (or at all). You are also going to get a load of opinions about battery use.
 
RE: day-to-day "average" workloads and their variances ...

Hi all,

It is my opinion...

I do not believe you can compare battery life tests while doing so-called "average" workloads. The reasons are manyfold, but as a single example let's consider Safari. Numerous websites have ads, and many ads use Flash. Flash is notorious for using CPU cycles and thus battery life, so unless you visit precisely the same web sites and remain on each page for exactly the same time intervals during your Lion/ML tests, then I think it is nearly impossible to compare these "average" workloads battery lives. I think the only accurate tests are ones performed under controlled conditions, as I indicated in my earlier posting.

It is fairly easy to imagine that during an "average" workload day, one might spend more time on a website that has five flash advertisements running on one day under ML, than on another day under Lion, thus negating any comparison of battery lives on the two systems, especially if we are only talking about 45 minutes of differences. Or, on the second day spotlight just happened to be indexing more because you altered more directories before the second day, or ...

To support this, I notice that my actual battery lifetimes (meaning the times I run on battery power before the laptop's battery is exhausted) vary from about 4 hours to over 7 hours for what I consider to be my own "average" workload days. I chalk up this 3 hour difference in battery lifetimes to the variance I naturally have in my own "average" workloads -- some days I use battery power faster than on other days, even though I consider all of these days to be of "average" workload. So, I would report my battery lifetimes as 5.5 +- 1.5 hours where +- means "plus or minus", not just as 5.5 hours.

Switon
 
Well Switon,

For what it's worth, after updating my laptop simply does not last as long as it used to before I updated... noticeably. Same workload, same stuff, different OS. I don't have the timer on the battery meter enabled. Just noticed it while working.
 
RE: non-parametric statistics and the null hypothesis...

Hi kfergiez,

I have a proposal for you, something that I'd love to know myself.

I'll be more than happy to perform the non-parametric statistics testing the null hypothesis (no battery lifetime difference) if you can provide me with the data, as I can't do these experiments myself since I don't have access to Lion. What I would really like are ten "controlled" tests of battery lifetimes under each OS, Lion and ML. By "controlled" (see my earlier post for a fuller description) I mean that you are not actively using the computer, it is just sitting there carrying out some calculation (that takes longer than the battery life). While these 20 data are those that I'd really like to have, I will settle on ten "uncontrolled" tests on each OS, and by "uncontrolled" I mean that you use your machine doing what you consider to be your "average" workload for each of the 20 experiments. If you collect the data, I'll do the statistics. [As I mentioned earlier, my own "average" workload battery lifetimes range from about 4 hours to 7 hours --- I guess, for me, some days are more "average" than others, to paraphrase George Orwell's Animal Farm.]

Regards,
Switon

P.S. I'd love to do these tests myself, but I don't have Lion and so cannot perform the controlled experiments to compare Lion and ML. But if you will help me with collecting the data, I'll do the math.
 
Hey... I am a middle school science teacher, and a physics enthusiast... I'd love to do something like that.

I'll let you know what I find. It'll take several days though.
 
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