On Mar 16, 2007, at 9:02 , Richard A. Smith wrote:
Here's the 411 on the battery problems.
The gas guage IC in the batteries has EEPROM in it where the EC
code stores lots of parameters on the type and state of the
battery. Under certain low voltage conditions when writing the
data the timing on the one-wire bus is marginal and the EC ends up
writing lots of 0xFF's to the EEPROM.
Recent version of the EC code have a couple of sanity checks when
the EC reads this data. The 0xFF's trip the error handling and the
charging state machine restarts, reads out the bogus data again,
gets errors, lather, rinse, repeat.
There is currently no method of recovery in EC code. So once the
EEPROM gets corrupted the laptop will will never charge the battery
again.
I spoke with quanta about this issue on the phone tonight and turns
out they have also discovered this and added some write
verification checks. They released PQB81 a few hours ago. I will
be releasing a new firmware (B81) tomorrow with this updated EC code.
Although B81 may stop future corruption from happening it will not
fix all the current broken batteries. I spoke with quanta about a
method of re-initializing the EPROM data to default values so we
can recover all the batteries that are dead. They said they were
going to look into it.
In the meantime I'm going to work on a few ideas that I have so
that we can recover the batteries in the field. Stay tuned.
I can confirm that B81 does not seem to have any effect on my dead
battery. I used the readEC program attached to #1051 but it's all
zeros, a single byte was 0f I think - anyone interested in the
output? Note this is not a LiFe.
- Bert -
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