| Message ID | 358665e3f4f9ec105dc2f8a2dc6dd98dbe761fae.1537930252.git.baolin.wang@linaro.org (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
| Series | [v2,1/4] power: supply: core: Introduce one property to present the battery internal resistance | expand |
On Wed, Sep 26, 2018 at 4:59 AM Baolin Wang <baolin.wang@linaro.org> wrote: > Introduce one property to present the battery internal resistance for battery > information. > > Signed-off-by: Baolin Wang <baolin.wang@linaro.org> > --- > 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.) 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"? Yours, Linus Walleij
Hi Linus, On 26 September 2018 at 16:00, Linus Walleij <linus.walleij@linaro.org> wrote: > On Wed, Sep 26, 2018 at 4:59 AM Baolin Wang <baolin.wang@linaro.org> wrote: > >> Introduce one property to present the battery internal resistance for battery >> information. >> >> Signed-off-by: Baolin Wang <baolin.wang@linaro.org> >> --- >> 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.
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@linaro.org> wrote: > > On Wed, Sep 26, 2018 at 4:59 AM Baolin Wang <baolin.wang@linaro.org> wrote: > > > >> Introduce one property to present the battery internal resistance for battery > >> information. > >> > >> Signed-off-by: Baolin Wang <baolin.wang@linaro.org> > >> --- > >> 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". -- Sebastian
On 26 September 2018 at 20:45, Sebastian Reichel <sre@kernel.org> 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@linaro.org> wrote: >> > On Wed, Sep 26, 2018 at 4:59 AM Baolin Wang <baolin.wang@linaro.org> wrote: >> > >> >> Introduce one property to present the battery internal resistance for battery >> >> information. >> >> >> >> Signed-off-by: Baolin Wang <baolin.wang@linaro.org> >> >> --- >> >> 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.
diff --git a/Documentation/devicetree/bindings/power/supply/battery.txt b/Documentation/devicetree/bindings/power/supply/battery.txt index f4d3b4a..25b9d2e 100644 --- a/Documentation/devicetree/bindings/power/supply/battery.txt +++ b/Documentation/devicetree/bindings/power/supply/battery.txt @@ -22,6 +22,7 @@ Optional Properties: - charge-term-current-microamp: current for charge termination phase - constant-charge-current-max-microamp: maximum constant input current - constant-charge-voltage-max-microvolt: maximum constant input voltage + - internal-resistance-micro-ohms: battery internal resistance Battery properties are named, where possible, for the corresponding elements in enum power_supply_property, defined in @@ -42,6 +43,7 @@ Example: charge-term-current-microamp = <128000>; constant-charge-current-max-microamp = <900000>; constant-charge-voltage-max-microvolt = <4200000>; + internal-resistance-micro-ohms = <250000>; }; charger: charger@11 { diff --git a/drivers/power/supply/power_supply_core.c b/drivers/power/supply/power_supply_core.c index e853618..9f3452f 100644 --- a/drivers/power/supply/power_supply_core.c +++ b/drivers/power/supply/power_supply_core.c @@ -579,6 +579,7 @@ int power_supply_get_battery_info(struct power_supply *psy, info->charge_term_current_ua = -EINVAL; info->constant_charge_current_max_ua = -EINVAL; info->constant_charge_voltage_max_uv = -EINVAL; + info->internal_resistance_uohm = -EINVAL; if (!psy->of_node) { dev_warn(&psy->dev, "%s currently only supports devicetree\n", @@ -616,6 +617,8 @@ int power_supply_get_battery_info(struct power_supply *psy, &info->constant_charge_current_max_ua); of_property_read_u32(battery_np, "constant_charge_voltage_max_microvolt", &info->constant_charge_voltage_max_uv); + of_property_read_u32(battery_np, "internal-resistance-micro-ohms", + &info->internal_resistance_uohm); return 0; } diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h index f807691..019452d 100644 --- a/include/linux/power_supply.h +++ b/include/linux/power_supply.h @@ -326,6 +326,7 @@ struct power_supply_battery_info { int charge_term_current_ua; /* microAmps */ int constant_charge_current_max_ua; /* microAmps */ int constant_charge_voltage_max_uv; /* microVolts */ + int internal_resistance_uohm; /* microOhms */ }; extern struct atomic_notifier_head power_supply_notifier;
Introduce one property to present the battery internal resistance for battery information. Signed-off-by: Baolin Wang <baolin.wang@linaro.org> --- Changes from v1: - New patch in v2. --- .../devicetree/bindings/power/supply/battery.txt | 2 ++ drivers/power/supply/power_supply_core.c | 3 +++ include/linux/power_supply.h | 1 + 3 files changed, 6 insertions(+)