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Author Topic: Resetting security circuit in a Laptop battery - anyone with experience?  (Read 2579 times)

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Offline SoerenTopic starter

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Hi all,

Background:
My Netbook (Acer Aspire One), which, last time I used it, was good for more than 7 hours of runtime, decided to quit on me (I probably didn't recharge it last time I used it and it's about 3 months ago or so).

After trying to let it hang on the charger overnight with no luck, I broke the casing of the battery and all the cells (18650's) was still perfectly balanced although they were down to 2.41V.
I recharged and rebalanced the cells one by one the hard way and they seem fine, but the security circuit don't know any of that of course, so still refuse to make me happy.

I have found some software and hardware for running on a PC with a parallel port, which should be able to reset such circuits, but the chips in my battery isn't mentioned (although some with very close type numbers are).
If I were to go into a battery restore business, that would be fine, but for a single battery, around price of $225 is a bit hilarious, when I can get a new battery for like $84.

Alternatively, I could find the datasheets for the chips on-board, spend some time reading, device a circuit and get it fixed, but once again, the time spend wouldn't be justified for repairing a single battery.

The reason for wanting to repair it, instead of just shelling out for a new one is twofold - I dislike adding to the landfills with what is actually working stuff. And if there's a quick fix, $84 is like 5 bottles of Scotch or some addendum to the toolbox or partsbin.


The Question:
Simple as it is... Does any of you have experience necromancing a security circuit In a lithium battery and care to share?

From my net searches on the subject, most people are dealing with run down cells and apart from the manufacturers, the circuits are considered some sort of dark arts  :-\
My cells are fine, very fine actually, so if anyone could help me keep them out of LED flash lamps and such, I would be very thankfull.
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline billhowl

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Re: Resetting security circuit in a Laptop battery - anyone with experience?
« Reply #1 on: October 25, 2010, 07:14:38 AM »
Take a look at this article
Quote
The Smart Battery routines, located in sbcomm.c, are based on bit-banged I2C 68HC11/Imagecraft software. I converted them to AVR/GCC and added information and functions specific to the Smart Battery spec. Take a look at sbcomm.h for the available SB commands. The ATMEGA8 has a built in I2C port but I did not use it. These routines could be extracted and used separately from the charger if desired, say, to monitor battery status of your robot during use. It provides some useful information such as voltage, amps, time remaining until recharge required (based on current usage rate), percent capacity, temperature, status flags, etc.

http://www.seattlerobotics.org/encoder/200210/lithiumion.htm

Offline SoerenTopic starter

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Re: Resetting security circuit in a Laptop battery - anyone with experience?
« Reply #2 on: October 25, 2010, 09:49:34 AM »
Hi,

Take a look at this article
[Snip]
Thanks a lot!
When I bookmarked the page, I realized I had already done so recently, when I stumbled over the page but didn't have time to read it, as I was chasing some other info.

This is good info for later, but for my immediate needs, I was kinda hoping for something I could do in less than an hour - It sure would be great if they had made a reset pin for making it virgin, but I assume they earn too well by not doing it.

One thing that I'd have to try though. The article mentioned that 2 of the terminals should be shorted for it to work, and I have only tested it out of the notebook, so perhaps it will power up now that the cells are back up. I'm crossing my fingers  ;D
It'll have to wait though as I am away for most of this evening.

Thanks again  ;D
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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