I understand the battery problems. (finally)

[Jim Gettys]

Yup.  Sounds like we need to send you a battery.  I'll ask Lindsay to
get one out to you.
                               - Jim

On Thu, 2007-03-22 at 17:49 +0100, Bert Freudenberg wrote:
> 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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-- 
Jim Gettys
One Laptop Per Child