The correct way to use your MacBook's battery

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Good question Ben_E

I've never been able to get a consistent answer from Apple about this
question of the threshold charge levels that trip the cycle count
register in the battery. Nor have I been able to find any firm spec on
this. (Try to find out the megapixel rating on your iSight camera.)

Your data however seems to fit well with the average machines that
I've been seeing over the past few years, e.g. at one year out most
users have around 150 charge cycles. Apple's own specs on Li-ion
batteries suggest that normal battery life is 300 cycles after which
time it is expected that the power capacity of the battery will drop to
80% of its original rating and decline from there.

So, you seem to fit this average user experience I'm seeing where they
get about two years of life from a battery before having to replace it.
That is why this new built-in design on the MBP's is really quite a
good value if it lives up to its promotion. Apple tells us to expect up
to 1000 recharge cycles which is getter than 3X my experience for
current batteries. If this turns out to be only 800 cycles, then it is a
bargain if Apple also live up to the estimated change-out price of
$170 for a 15" model. Right now, the new battery is not classified as
a user-replaceable part but I expect this will change given the current
okay to open the case to change memory or hard drives. It uses a
simple single-cable plug. Maybe they are concerned with collecting
use data at this point.

With regards to what constitutes a "charge cycle", perhaps readers
here with any Macbook less than two years old might try: going into
the system profiler and check your current charge cycle count on a
fully charged battery and then run it on battery and let the indicator
fall to 80% and plug in the charger. When it gets to 100%, check the
cycle count and see if it incremented by 1 cycle. If not, then run on
battery and let it fall to 60% and recharge and recheck. I'd be
interested in seeing what you find.

Finally, with regards to my earlier post on my experience with getting
the best life on these batteries, Apple does recommend at their
support site that you do not run the machine ALL of the time off of
the AC adapter and if you are not mobile that you should periodically
disconnect the adapter and allow the battery to fall below 50% and
recharge it. This 50% value is mentioned a few places, so perhaps this
is the value that changes the state of the battery.

And yes, the MagSafe connector - while a terrific improvement - does
have its problems. Being a two pole device, users can insert it in any
direction to use it. I see these coming in all of the time looking like a
pretzel right at plug (not counting students who seem to love to tie
them in knots - probably the same ones that constantly twist their
hair) often with the outer sheath split open. A good improvement on
the design would be to make the low voltage side cable plug into the
AC adapter end as well with a MagSafe connector. This shouldn't add
much to the price, would keep the adapters from getting tripped over
and would enable users to replace a bad cable easily without the cost
of replacing the entire adapter. Also the random nature of how the
cable would be connected would reduce the stress always happening
at just one end which should theoretically double its life.

Posted by: r.u.FED.up.2   Posted on: 07/03/09 You are currently: a Guest | Members login | Terms of Use

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