Building notes, projects, and occasional rants


I bought a new batery for my laptop in October 2008. A couple of days ago, I started getting abrupt shutdowns, even before the low-battery warning pops up.

And it doesn't enter sleep mode. It just goes puf, and powers off.

Searching around for similar reports, it seems that my battery is kaput. Either a cell is damaged, or the battery is starting to swell. I'm guessing its the first one, since I don't notice any swelling.

This is the third battery I've burned through with this laptop. The first one lasted from May 2006 up-to sometime early 2008. The second one lasted a couple of months, then started to swell. And now this one, since Mon Oct 27 23:20:47 2008 until today.

Now you might wonder how can I know the exact date and time that I got the new battery. The answer is simple. Before I switched to the new battery, I wrote this script, x-apple-log-battery-status, a quick and very dirty way of keeping track of all the stats about my battery.

I run it every 300 seconds. Given that the script logs the data to disk, it has to spin-up the disk and therefore influence the data collected, but I use my laptop intensely anyway. It rarely sleeps.

So I've recorded 53605 samples of my battery life. The first record is this:

t:1225149647 # Mon Oct 27 23:20:47 2008
fully_charged: No
is_charging: Yes
external_connected: Yes
cycle_count: 1
time_remaining: 38
max_capacity: 6869
voltage: 12485
current_capacity: 6516
design_capacity: 6300
temperature: 3082

The last one so far:

t:1266581334 # Fri Feb 19 12:08:54 2010
fully_charged: Yes
is_charging: No
external_connected: Yes
cycle_count: 561
time_remaining: 25013
max_capacity: 3367
voltage: 12459
current_capacity: 3335
design_capacity: 6300
temperature: 2944

As you can see, I've still have about 50% of the original capacity, but with 561 cycles.

The entire file is here: battery_log.txt.gz, 736Kb of gzipped data. You can do whatever you want with it, I only ask that if you do something interesting, send me a link.

Someday I'll dump this into a spreadsheet and do some pretty graphics.