Andrew,

Thank you for this further clarification.  However, I would like to
question you further on your comment when you say, ". . . you don't have
to do a battery calibration . . .."  Surely, if you don't, you have no
way of keeping track of how much battery is left.  In our case, for
example, without calibrating, this battery is just crashing out when it
likes, with no "Battery Low" or "Battery Critical" message.  Each time
the machine is reset as it crashes and we are asked to enter the date,
so I guess that must be the 456 reset or the "Big Engineers' one".

If you accept that it is needful to know what battery remains then
perhaps you could rethink this question of whether or not we need to
"calibrate".


--
Carol
[EMAIL PROTECTED] 
Who is now very frustrated after a second battery fit and still no word
from the engineers here in the UK!



-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of
[EMAIL PROTECTED]
Sent: Sunday, October 09, 2005 10:32 PM
To: [email protected]
Subject: [Braillenote] battery calibration


Hi everyone on the list,

   I've been at Humanware for a few months now and have been reading
this 
list, and thought I could clarify a couple of issues about battery 
calibration, since that's one of the things I've been working on.
Here's 
my understanding:

Firstly, you don't have to do a battery calibration - it just helps the 
unit keep track of exactly what your battery capacity is.  All batteries

degrade with use and after 12 months you'd expect a reduction in
capacity. 
 If you never calibrate your unit, it may think that the battery has
more 
juice left than it really does.  If it was me, I'd probably try to do a 
recalibration once every few months and leave it running overnight so I 
don't have to listen to it .  In addition, some battery types (including

NiMH which the mPower uses) need a few full charge cycles before they 
reach full capacity - for example, this is what the instructions for my 
electric drill said.

Secondly, the mPower and BrailleNote classic systems measure remaining 
charge in different units.  mPower gives a reading of how many
milliAmpere 
hours it thinks are left in the battery.  So a battery with a design 
capacity of 1800 mAh will probably reach the 1700 - 1800 mAh range.  The

classic doesn't read in milliampere hours but just reads off the 
information directly from the fuel gauge chip - the one I'm playing with

now goes says it's last discharge was 27,000-ish.  So don't worry if
your 
mPower doesn't go up as high as that - it's not supposed to.

hope that's useful!  I'm copying Dean on this in case he wants to add to

or clarify my clarification <grin>

regards,

Andy.

----
Andrew Riden 
Software Development Engineer 
HumanWare Ltd
11 Mary Muller Drive,
Christchurch ,
New Zealand .

DDI +64 3  940 2264
Fax +64 3  384 4933 
Email: [EMAIL PROTECTED] 
Internet: www.humanware.com 

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