John Watlington wad at
Thu Aug 6 22:13:31 EDT 2009

The context is that we are trying to ensure that an Maximum Power  
Point Tracking algorithm
can be implemented on the DC power input of the XO-1.5.

On Aug 5, 2009, at 10:56 PM, Richard A. Smith wrote:

> John Watlington wrote:
>> The problem comes from the need for the algorithm to start from a  
>> position
>> of low current drain.   The MPPT algorithm should probably be  
>> disabled
>> when the laptop is running and the battery is below some threshold  
>> (say 10 -15% ?)
> Yep.  I don't think it will matter though.  The core of the problem  
> is that our peak CPU power draw is > 10W where on gen 1 is was  
> <=10W and we aren't going to fix that.

We should play with having the power daemon clock down the CPU in  
some cases.

Perhaps modifying adding a "solar power provided or removed" subtype  
to the
Battery Status Change SCI interrupt from the EC ?
This could be used to limit the peak processor clock when the battery  
is very low.

Limiting the peak processor clock when the battery is very low and we  
have any DC input might extend the battery life slightly as well.

Comments ?

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