15C LE spike fix

[Jeff O.]

(04-28-2014 07:37 AM)Thomas Radtke Wrote:  Lyuka devised a fix for power spikes occuring at each key press of the 15C LE (as far as I understand this matter):

http://www.hpmuseum.org/cgi-sys/cgiwrap/...ead=208839

Are there any experiences with this fix? Does it improve the faulty brownout detection in real use cases?

I'm not sure how qualified I am to comment on this, but I did perform some battery life tests as described in this thread from the old Forum.

Based on the results of my battery tests and discussion in that thread (especially by Katie Wasserman), I don't see how adding a capacitor will have any impact on the faulty brown-out detection. Actually, brown-out detection is completely non-existent, not necessarily just faulty. Adding the capacitor will have no impact on current draw from the batteries during program execution. As soon as the program starts, the capacitor will discharge in a very short time, then the load will be carried solely by the batteries. A capacitor might mitigate the current spike and resultant voltage drop during key presses, but eventually, the battery voltage will drop low enough that a key press, or a function call, or running a program, or maybe even recharging the capacitor after it discharges for a key press, will drop the voltage below the threshold at which the processor can operate, and the processor will shut down and memory will be flushed.

Corrections and comments from those who know more than me are encouraged.