01/23/2013, 07:17 PM
a few days ago, when I tried to recalibrate my 2 year old Palm battery, I encountered the popular problem with no solution. Dr Battery instructed me to connect the charger but only a few seconds after I did that, the calibration failed. Today I got the same error again with another battery but now I guess to know how to solve it.
The problem develops by the fluctuating current the device consumes. Every non-ideal power source adjusts its voltage to the current it needs to deliver. So if the current increases, the voltage decreases as reaction of the load and keeps decreasing until the battery is empty, even if the current keeps stable. Your phone battery also behaves that way but unfortunately the current, the phones takes, isn't stable. It alternates between 150mA and up to 650mA (Pre -) even if your doing nothing except waiting for Dr Battery to instruct you to connect the charger. The most of the time while waiting for the Dr, your phone takes about 150mA at a voltage of about 3,518V (empty battery!) which decreases slowly until it reaches the "empty point" indicated by the LEARNF-flag. But sometimes the current suddenly increases to 300mA and more which leads to the effect described above. As reaction to that gain in current, the voltage drops heavily and reaches the empty point which in turn will be recognized by the Maxim Fuel Gauge IC within the battery and handled by enabling the LEARNF-flag. Once this flag was set, Dr Battery orders you to connect the charger to start calibration. But the IC only stays in calibration mode as long as the voltage is stable and below the empty point, until you connect the charger and the voltage increases heavily at about 3,9V. If there is just a slight increase in voltage, the IC immediately leaves calibration mode, clears the LEARNF-flag and you get the interrupted calibration error in Dr Battery, which is exactly the reason why your calibration fails. Once the program told you to charge your device now, or even in the meantime, the phone slowly reduces its current consumption back to the normal 150mA. As reaction to that decrease in current the battery revives and increases its voltage above the empty point, which at last leads the IC to leave calibration mode. This effect also occurs if you don't follow Dr Battery's instruction to connect the charger and just wait to see what happens next. But you can avoid that problem by producing enough workload that the current increases heavily and keeps at a high level all the time until you're ordered to connect the charger. Just follow these instructions:
1.) Start Dr Battery and enter the calibration screen (DON'T close it during one of the following steps, just
minimize it to a card at step 3!)
2.) Discharge your device normally until it reaches 3,580V - 3,518V (Don't discharge it too long that way,
otherwise your device might turn off immediately when following the next steps!)
3.) Produce enough workload for example by activating the Mobile Hotspot. This will increase the current
consumption at about 600mA which is enough to lower battery's voltage below the empty point and keep it
there as long as the Hotspot is activated
4.) Switch back to Dr Battery immediately (Don't turn off the Hotspot!)
5.) Once the Dr instructs you to connect the charger do it.
6.) Wait until Dr Battery displays "calibrating" before you may disable the Hotspot to increase the charging
7.) Wait until the program displays calibration successful and you're done
Attention! Don't discharge your phone too long as described in step 2 as your device may shutdown only a few seconds after activating the hotspot if the voltage is already at a very low level when performing step 3. But don't follow step 3 too early as higher voltages result in an inaccurate calibration which leads to a battery health which is below the actual one.
I've tested the steps described above four times without removing the battery or restarting the device even a single time and it worked properly at every of that four attempts. Let me know if this also worked for you.