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Building An Open Source ThinkPad Battery

If you personal a pc that’s were given a couple of years at the clock, you’ve most certainly pondered getting a alternative battery for it. Which method you additionally understand how a lot legit OEM packs price in comparison to the shady eBay clones. You can ceaselessly get two or three of the knock-offs for a similar worth as a unmarried actual battery, however they by no means closing so long as the originals. If they even paintings correctly in any respect.

Which is why [Alexander Parent] made up our minds to take the street much less traveled and scratch constructed a customized battery for his ThinkPad T420. By opposite engineering how the battery pack communicated with the pc, he reasoned he would be capable of get a hold of an open supply firmware that labored a minimum of in addition to what the the 3rd birthday party ones are operating. Which from the sounds of it, wasn’t an overly top bar. From a simpler point of view, it additionally supposed he’d be capable of create the next capability battery pack than what used to be commercially to be had must he selected to.

A good judgment analyzer stressed out in between one of the 3rd birthday party batteries and a spare T420 motherboard allowed [Alexander] to seize the entire SMBus chatter between the two. From there he wrote some Arduino code that will mimic a battery as an evidence of thought. He used to be bogged down just a little via an undocumented CRC test, however finally he used to be ready to get a hold of a reasonably mature firmware that even lets you supply a customized dealer title and fashion quantity to your pack.

The code used to be shifted over to an ATtiny85, with a voltage divider stressed out as much as one of the pins so it could actually learn the pack voltage. [Alexander] says his firmware nonetheless doesn’t do a super activity of reporting the true battery capability closing, however it’s shut sufficient for his functions. He got here up with a easy PCB design to carry the MCU and give a boost to parts,  which sooner or later he plans on placing within a 3-d published case that in reality plugs into the again of his T420.

This undertaking is clearly nonetheless in a moderately early level, however we’re very to peer [Alexander] take it the entire means. The ThinkPad has lengthy been the hacker’s favourite pc, and we will call to mind no gadget extra worthy of an absolutely open {hardware} and tool battery pack.