discharge the battery during the long charge (trigger very wide)

[Al Johnson]

On Tuesday 23 February 2010, Yoric Kotchukov wrote:
> Saluto!
> 
> Linux neo 2.6.29-GTA02_qtmoko-v16-mokodev #1 PREEMPT Sun Dec 20 18:36:16
>  CET 2009 armv4tl GNU/Linux
> 
> When you long to find a charger (usb/wall), FR A6 first gaining charge
> (CAPACITY = 100), then runs down a small current. After a half days:
> 
> POWER_SUPPLY_STATUS=Not charging
> POWER_SUPPLY_HEALTH=Good
> POWER_SUPPLY_VOLTAGE_NOW=4027000
> POWER_SUPPLY_CURRENT_NOW=9375
> POWER_SUPPLY_CHARGE_FULL=1163463
> POWER_SUPPLY_CHARGE_NOW=970861
> POWER_SUPPLY_TEMP=286
> POWER_SUPPLY_TECHNOLOGY=Li-ion
> POWER_SUPPLY_PRESENT=1
> POWER_SUPPLY_TIME_TO_EMPTY_NOW=391620
> POWER_SUPPLY_TIME_TO_FULL_NOW=3932100
> POWER_SUPPLY_CAPACITY=83
> POWER_SUPPLY_ONLINE=1
> 
> 1/5 the charge is lost at the moment (((

It's not a bug, it's a feature ;-)

Seriously, it really is a feature. Holding LiIon batteries at 100% charge for 
extended periods degrades the battery. If we did that then you would soon have 
a battery that could only hold 80% (or less) of the charge that it could 
originally. Instead we let the battery discharge a bit, then top it up, which 
helps preserve the battery's ability to hold charge. The worst case is that 
you unplug the charger just before charging starts again. You still have ~80% 
of the original capacity, so runtime is no worse than with the battery damaged 
by holding at full charge.