| Battery Characteristics |
| |
| The devicetree battery node provides static battery characteristics. |
| In smart batteries, these are typically stored in non-volatile memory |
| on a fuel gauge chip. The battery node should be used where there is |
| no appropriate non-volatile memory, or it is unprogrammed/incorrect. |
| |
| Upstream dts files should not include battery nodes, unless the battery |
| represented cannot easily be replaced in the system by one of a |
| different type. This prevents unpredictable, potentially harmful, |
| behavior should a replacement that changes the battery type occur |
| without a corresponding update to the dtb. |
| |
| Required Properties: |
| - compatible: Must be "simple-battery" |
| |
| Optional Properties: |
| - voltage-min-design-microvolt: drained battery voltage |
| - voltage-max-design-microvolt: fully charged battery voltage |
| - energy-full-design-microwatt-hours: battery design energy |
| - charge-full-design-microamp-hours: battery design capacity |
| - precharge-current-microamp: current for pre-charge phase |
| - 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 |
| - factory-internal-resistance-micro-ohms: battery factory internal resistance |
| - ocv-capacity-table-0: An array providing the open circuit voltage (OCV) |
| of the battery and corresponding battery capacity percent, which is used |
| to look up battery capacity according to current OCV value. And the open |
| circuit voltage unit is microvolt. |
| - ocv-capacity-table-1: Same as ocv-capacity-table-0 |
| ...... |
| - ocv-capacity-table-n: Same as ocv-capacity-table-0 |
| - ocv-capacity-celsius: An array containing the temperature in degree Celsius, |
| for each of the battery capacity lookup table. The first temperature value |
| specifies the OCV table 0, and the second temperature value specifies the |
| OCV table 1, and so on. |
| - resistance-temp-table: An array providing the temperature in degree Celsius |
| and corresponding battery internal resistance percent, which is used to look |
| up the resistance percent according to current temperature to get a accurate |
| batterty internal resistance in different temperatures. |
| |
| Battery properties are named, where possible, for the corresponding |
| elements in enum power_supply_property, defined in |
| https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/power_supply.h |
| |
| Batteries must be referenced by chargers and/or fuel-gauges |
| using a phandle. The phandle's property should be named |
| "monitored-battery". |
| |
| Example: |
| |
| bat: battery { |
| compatible = "simple-battery"; |
| voltage-min-design-microvolt = <3200000>; |
| voltage-max-design-microvolt = <4200000>; |
| energy-full-design-microwatt-hours = <5290000>; |
| charge-full-design-microamp-hours = <1430000>; |
| precharge-current-microamp = <256000>; |
| charge-term-current-microamp = <128000>; |
| constant-charge-current-max-microamp = <900000>; |
| constant-charge-voltage-max-microvolt = <4200000>; |
| factory-internal-resistance-micro-ohms = <250000>; |
| ocv-capacity-celsius = <(-10) 0 10>; |
| ocv-capacity-table-0 = <4185000 100>, <4113000 95>, <4066000 90>, ...; |
| ocv-capacity-table-1 = <4200000 100>, <4185000 95>, <4113000 90>, ...; |
| ocv-capacity-table-2 = <4250000 100>, <4200000 95>, <4185000 90>, ...; |
| resistance-temp-table = <20 100>, <10 90>, <0 80>, <(-10) 60>; |
| }; |
| |
| charger: charger@11 { |
| .... |
| monitored-battery = <&bat>; |
| ... |
| }; |
| |
| fuel_gauge: fuel-gauge@22 { |
| .... |
| monitored-battery = <&bat>; |
| ... |
| }; |