On 26 September 2018 at 20:45, Sebastian Reichel <sre@xxxxxxxxxx> wrote: > Hi, > > On Wed, Sep 26, 2018 at 04:30:39PM +0800, Baolin Wang wrote: >> Hi Linus, >> >> On 26 September 2018 at 16:00, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: >> > On Wed, Sep 26, 2018 at 4:59 AM Baolin Wang <baolin.wang@xxxxxxxxxx> wrote: >> > >> >> Introduce one property to present the battery internal resistance for battery >> >> information. >> >> >> >> Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx> >> >> --- >> >> Changes from v1: >> >> - New patch in v2. >> > >> > I'm a bit confused by the physics in this patch. >> > >> > The internal resistance of a battery is not a constant in its life cycle, >> > this varies over the age of the battery, and the reason I thing is >> > chemical residuals accumulating on the anode and cathode inside >> > the battery and the energy storage medium aging. (Plus/minus my >> > ignorance about how batteries actually work.) >> >> Yes, you are right. The internal resistance can be affected by >> temperature or battery age or other factors. But our solution just >> uses one constant internal resistance to calculate OCV value to look >> up the capacity table when system boots on, in this case we do not >> need one more accuracy OCV, since we will calculate the battery >> capacity in future. So we just introduce one estimation constant >> internal resistance. >> >> > >> > AFAIK the fact that the internal resistance varies is of high >> > importance for people developing algorithms of battery capacity >> > and longevity. Such that some (hardware) capacity monitors go >> > to great lengths to measure with high precision the current >> > internal resistance of the battery for their algorithms. >> > >> > Sorry for making things more complex, but should it be named >> > "factory-internal-resistance-micro-ohms" or >> > "typical-internal-resistance-micro-ohms"? >> >> I am fine with this change. If Sebastian also agree with this change, >> I will fix. Thanks for your reviewing and comments. > > Ack. > > FWIW for proper battery status you need to collect battery specific > statistics, that is the reason fuel gauge chip providers recommend to > combine the chip with the battery cells into a "smart battery". OK. I will rename it as "factory-internal-resistance-micro-ohms" in next version. Thanks. -- Baolin Wang Best Regards
