my daring experiment

My current laptop is now more than three years old. I bought it in mid-2005 as a kind of uni-and-netgaming workhorse, which purpose it served very well. I’m still using it on and off, out and about and at home away from the desktop, mainly as a glorified mp3 player/MSN chatting device/internet browsing object.

I bought it with two batteries, which in 2005 were capable of running this thing – a 1.6ghz Pentium M Centrino laptop with 15″ LCD – for over ten hours straight. I barely took my power adapter anywhere, except for the first few days before it knew what the hell kind of battery life it possessed.

Even today, new laptops are considered awesome and portable and convenient if they manage 3 hours between charges.

Currently I’m eyeing off my next huge waste of money drool-inducing plaything thoroughly justifiable computer purchase, and was curious about how much of my battery life had actually been lost, for purposes of reselling.

I started scribbling times and percentages down in my trusty old notepad.exe, before wondering about the easiest way to convert the data to some kind of pretty chart for blogging the whole adventure. I was about to go download openoffice again, before remembering Google had some kind of web-based office clone of its own.

And, as it turns out, Google Docs is actually pretty damn cool.

This is the chart it made from my scribbling. Click it for the full-size image and the rest of the spreadsheet (top left, click Sheet 1 to see my fantastically diligent data recording).

I didn’t just leave the thing running in a corner with the LCD screen and wireless card turned off; I actually sat there using the thing, screen on full brightness, heavily browsing the net (I was researching dietary salt at one point) and generally giving it the same kind of workout it’s had for the past 3 years. Pretty much the worst case usage scenario for a machine like this, since as a computer it’s no longer relevant for any kind of modern gaming.

In summary: I have pretty much two hours of usable battery life left. In 120 minutes of logging, my laptop sucked its lithium polymer modular bay battery dry in the first three quarters of an hour flat, while the good old lithium ion primary battery kept chugging for much longer.

Laptops with dual batteries drain the secondary one down to 10% first, then the primary down to 10%, then back to the secondary to 5% and so on until it’s completely out of juice. They also charge the primary to 80% before touching the other one, so it doesn’t waste time charging the battery you’re likely to remove and replace with a power-hungry DVD drive if you get bored on the train.

I terminated the experiment at exactly two hours, because for six minutes straight the batteries read 7% and 3% without changing. Battery readings become inaccurate to the point of garbage, once you get past a certain point. A couple of months ago, I actually ran the batteries into the ground for fun, completely emptying them of charge, to see what would happen; the laptop ran for a full 35 minutes with both batteries reading exactly 0% (estimated time remaining: 0 minutes) before turning off with a sad noise.

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