Hi, just recovered this account and a friend
(Karpour
) told me to post this here.
a couple of days ago i got a Jornada 820, thankfully it was working except for the battery, that was reporting the "can't communicate" error, when i took it apart it was already leaked, but not badly, so i took the cells out and replaced them with two nokia batteries with their own controller removed.
Original battery:
Experimental battery:
i guess at this point i have to give the disclaimer of playing with lithium batteries can be dangerous, so this is not a guide, but just to share the experiment, but I'm dumb so i kept going.
so doing this did nothing, the controller still indicated comunication errors and i didn't get any voltage on the pins, so i have two issues to fix.
i repaired the no voltage on the pins by reading datasheets, i noticed it had a really fancy fuse meant to protect the overcharge of the cells, this was blown.
it's supposed to have continuity between the two top pins
(and not the middle one
), i had nothing, so i just bridged this with a wire
(dangerous
) and yeah, i got 7.4ish Volts on the output, plugging this back on the device got it running without external power! nice, but still, no communications and that means no charge and the annoying popup.
what i did now was kinda a coincidence, i found the linux for the 820 website
Link copied the loader and the kernel to my cf card and booted, pretty fast, interesting but yeah, old linux.
i did this with the external power plugged and the battery, i rebooted the machine
(issuing the reboot command
) and after that i got windows ce again, no display, so i did a reset, that helped with the screen, i bypassed the welcome screen and restored a backup, and that's when i noticed that the battery was actually reporting a charge!
i unplugged it and it started going down, nice, looks like it's reading fine that info, so i plugged it back and bam! red light on the battery and the status started to go up.
it got stuck there and the red light went away, looks like probably it's reading maybe incorrectly, the batteries are probably not balanced at all, or who knows what kinda other issue can be, so right now I'm at the point of discharging the device, i connected a wifi card, dialled the modem and the brightness is on max and right now it has been sitting for like 2 hours
So, at this point i need to do some more experimenting and see if first it's possible to replicate this scenario
(disconnecting the cells and seeing if the controllers fails, repeat procedure to revive it
) and second see if i can source the fuse to do a more permanent repair and lastly see if it needs more calibration, if the controller is doing balancing correctly, test for over/under discharging, and other stuff.
I'm also interested to know if maybe someone has done this before, so we can compare info
i will update this when i get more info
Thanks for the space and I'm reading your comments.