We’ve all gotten bored of certain toys and left them on the shelf for months on end. But what do you do when this prolonged period kills the batteries? Well if you’re [Andrew] you take apart the battery pack and bring it back to life!
[Andrew] picked up one of those Panasonic Toughbooks awhile back and although it’s hardly a top of the line laptop specs-wise, it does have some pretty cool features: it’s shock-proof, splash-proof, and extreme-temperature-proof. It even had a touch screen before touchscreens were cool. Despite its durability, however, the laptop was left to sit for a bit too long, and the battery pack no longer accepted a charge.
[Andrew] quickly disassembled the battery pack and began measuring the cells with his trusty multimeter, assuming just one cell had gone bad. Curiously though, no cells reported 0V. What he did find was that each cell and sub-pack reported 2.95V, which is 0.05V below the “safe operating limits” of typical lithium ion cells.
Figuring he had nothing to lose he tried his luck by giving the cells a direct boost with his bench-top power supply. He supplied the entire pack with a constant voltage of 12V for about 3 minutes while monitoring the current, and stopped charging once they each reached 3.2v. He then put it back together and the battery pack suddenly accepted a charge from the laptop once again!
We realize this won’t always work for a dead laptop battery, but hey, what do you have to lose?