[olpc-nz] Battery LED flashing

Richard A. Smith richard at laptop.org
Tue Jan 5 08:10:16 EST 2010

On 01/03/2010 07:20 AM, Martin Langhoff wrote:

> the behavious sounds exactlt like a case of trickle charge. This
> triggers when the batt charge is so low that we cannot charge it (or
> measure it). When it happens, it's ususlly because a batt has not
> been used for a while.

The batteries are actually ok.  Trickle charge is the result of the way
the XO-1 power system is designed.  There is no dedicated battery 
charger IC.  The battery is connected directly to the main voltage rail. 
  The result of this that when you turn on the charging mosfet your 
system rail = battery voltage.  On XO-1 if you try to charge a battery 
that's dropped to a really low level you don't have enough headroom for 
the rest of the voltage regulators to work and the system dies.  So we 
bring the voltage back up gently to a level we can deal with before 
opening the electron flood gates.

> In terms of getting more low level info, get your hands  on a script
> called batman.fth (it's somewhere in the wiki ;-) )


> logs of the batt levels per cell, and you can read it/change it.

batman.fth does not do anything per cell.  There's no user serviceable 
parts per cell in the OLPC battery.

Richard A. Smith  <richard at laptop.org>
One Laptop per Child

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