Testing laptop battery writeup - Page 1
Forum section: electronics / projects

author: reagle
author_rank: Unknown
timestamp: June 22, 2013, 06:24:25 pm
content: I needed to check the condition of a laptop battery, so in the process I ended up creating this writeup.Hoping somebody will find it useful!http://kuzyatech.com/testing-laptop-battery-pinout-smbus-charge-capacity

author: Fraser
author_rank: Super Contributor
timestamp: June 22, 2013, 06:49:45 pm
content: Many thanks for this. Very useful.I have a pile of Compaq laptop batteries that I was given and their condition is not known yet. They look new but it would be great to see the information held on the management chip.Now to find a wallet friendly TI SMB interface

author: firewalker
author_rank: Super Contributor
timestamp: June 22, 2013, 07:00:34 pm
content: I wonder if someone could connect only the SMB pins of any battery to a laptop and useacpi -iBattery 0: Discharging, 74%, 03:50:46 remainingBattery 0: design capacity 5860 mAh, last full capacity 4728 mAh = 80%Alexander.

author: reagle
author_rank: Unknown
timestamp: June 22, 2013, 07:12:14 pm
content: The EV2300 board from TI I used was about $50 new. I see they occasionally go on ebay for $20. Other options include bus pirate or any other board talking I2C though you'd have to do a bit of work figuring out what data means. I'll see if I feel like making a tutorial on thatConnecting to SMBus only of another laptop could work as well. One gotcha in all cases- if the pack is overdischarged, it may need a wakeup charge before it starts talking. In some cases, like the one I described, that also requires figuring out that it needs a system present pin grounded before it even allows charge.Good (maybe) thing is, a huge percentage of these use TI chipsets and they are relatively consistent in their behavior

author: Fraser
author_rank: Super Contributor
timestamp: June 22, 2013, 07:18:47 pm
content: An interesting SMBUS hacking article here:http://media.blackhat.com/bh-us-11/Miller/BH_US_11_Miller_Battery_Firmware_Public_WP.pdf

author: reagle
author_rank: Unknown
timestamp: June 22, 2013, 07:29:11 pm
content: Very thorough piece of work. Puts mine to shame

author: Fraser
author_rank: Super Contributor
timestamp: June 22, 2013, 07:43:42 pm
content: But I would not have looked for it or known about how the SMBus may be accessed if it was not for your message. Thank youI will keep an eye out for an EV2300.I have a means to read SMBus data but not to display it as in the TI app.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: June 22, 2013, 08:13:45 pm
content: There appears to a useful software called BE2Works that can reprogram the eeprom after new cells are fitted in a battery. That could be useful where no compatible battery is available and the old one must be rebuilt.The EV2300 can be modified to work as a GPIO adapter for use with BE2Workshttp://be2works.com/http://be2works.com/Hardware.aspxhttp://be2works.com/Howitworks.aspxEV2300 modification (pretty simple)http://be2works.com/forum/viewtopic.php?f=2&t=195The GPIO adapter from TI looks pretty useful toohttps://estore.ti.com/USB-TO-GPIO-USB-Interface-Adapter-EVM-P960.aspx

author: peter.mitchell
author_rank: Super Contributor
timestamp: June 23, 2013, 10:08:32 am
content: Quote from: Aurora on June 22, 2013, 07:18:47 pmI love Charlie Millers work, his presentations are amazing too!

author: amyk
author_rank: Super Contributor
timestamp: June 23, 2013, 11:07:05 am
content: Here's the SBS spec, useful if you're reading/writing raw data:http://sbs-forum.org/specs/sbdat110.pdfApparently hasn't been updated since '99... but then again, the protocol is probably flexible enough that the last decade's improvement in battery tech hasn't required it to be changed.