Toshiba Satellite 440CDT - Laptop Battery Repair

A Toshiba Satellite 440CDT. Scored for the princely sum of $10.

A Toshiba Satellite 440CDT. Scored for the princely sum of $10.

On an adventure to a local... sort of antique/junk/anything store, I found this. A Toshiba Satellite 440CDT - a laptop from the early Pentium era. Complete with battery, featuring an internal CD drive (feat. a forgotten Foo Fighters CD) and internal 33.6K modem, I had to have it, as it looked in fairly decent condition. It also had a 56K generic brand modem in the card slot and no charger. The floppy drive was also absent. 

Upon getting it back to the workshop, I realised I didn't have any DC barrel jacks to fit the onboard Toshiba connector - quite a fat one, and none of my other laptop supplies would fit either. I also determined after some experimentation and judicious use of Google, that the laptop would refuse to power up if given a voltage in excess of 16.5V

 

A screengrab of Toshiba error codes from http://www.hardwareanalysis.com/content/topic/51345/

A screengrab of Toshiba error codes from http://www.hardwareanalysis.com/content/topic/51345/

Unfortunately I only had relatively modern laptop adapters all putting out in excess of 17V. I eventually found an adapter for my old EEE PC 901 netbook, which puts out 3A at 12V. That would have to do. Instead of driving around to find the appropriate connector, I simply soldered a wire to the centre pin of the existing jack for the positive lead, and found a ground point to solder to inside the laptop which I brought out through a tastefully drilled hole. Butchery? Yes. Quickly and tastefully done? ...arguably, also yes. Sometimes you're just trying to have some fun and don't want to get bogged down. I soldered these leads to a readily available 2.5mm DC jack which I have loads of (thanks to the Grav-A) and epoxied it in place.  

I'll definitely come back and clean this up one day. Promise.

I'll definitely come back and clean this up one day. Promise.

So, with adequate power connected, we had success - a whirr from the fans, that lovely '90s hard drive grind, and we were up and running! Greeted by a bit of ScanDisk and Windows 95. However, sadly, all was not well - the battery was showing up in Windows but was reading 0% - and was "charging" but the value wasn't going up at all. I decided to disassemble the pack. I was surprised after pulling stickers off that it was all just plastic pieces, clipped together - no screws were involved. I was able to pull the pack's case off with just my fingernails, without damaging anything. 

I counted 9 cells in the pack. They were in 3 parallel groups of 3, giving a nominal pack voltage of 10.8V. I was surprised to find that not only was each cell reading over 2.0V (a kind of point of no return for Li-Ion batteries) but they were also fairly close to being balanced across the whole pack (important to avoid... fires, pretty much). I decided to manually charge the pack myself. Rather then whipping up a cable to connect it to my hobby Li-Po/Li-Ion charger, I just stuck it on the ol' DC variable power supply, trickling a good 300mA or so into the pack and keeping a close eye on it. I got it up to 11.0V and was thirsty to try it out again - but alas, no. Windows still reported the pack at 0% charge and wasn't budging.

So where does this leave me? A later trip to the junk shop netted the missing external floppy drive and another matching Toshiba battery, which I haven't yet disassembled but an initial test showed the same problem. I'm currently thinking that some sort of onboard EEPROM has bricked the battery but haven't looked too closely into it. A closer look at the battery's PCB might show up something I can play with, but even if there is an EEPROM or similar, it'll be tough to figure out what data's on it and what needs to be changed to get the battery going again. I'm also unable to find any decent hardware info utilities that can give me further info either as Windows 9x software is rather rare on the web now - too old to need in normal use, not old enough to be vintage yet. If you've got any tips or helpful information, hit me up at scott@grav-corp.com or leave a comment below!