On Wed, Feb 15, 2017 at 4:53 PM, Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxx> wrote: > Hi, > > On 15/02/2017 01:46, Liam Breck wrote: >> >> On Tue, 14 Feb 2017 10:40:55 +0100 Quentin Schulz wrote: >>> This adds the constant-charge-current property to the list of optional >>> properties of the battery. >>> >>> The constant charge current is critical for batteries as they can't >>> handle all charge currents. >>> >>> Signed-off-by: Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxx> >>> --- >>> >>> added in v3 >>> >>> Documentation/devicetree/bindings/power/supply/battery.txt | 2 ++ >> >> Is constant-charge-current dependent on the battery (e.g. capacity, nominal voltage, etc) or the >> system (charger chip, input current/voltage, etc)? >> >> It belongs in Doc.../power/supply/battery.txt if it's a characteristic of the battery. >> >> Note, this page asserts that constant-current charging applies to NiMH batteries: >> http://power-topics.blogspot.com/2016/05/constant-voltage-constant-current.html >> >> Related properties to be added to battery.txt near-future in a patchset for the BQ24190 >> charger are as follows. These are not currently in enum power_supply_property, so the actual names >> are still to be decided. >> >> precharge-current-microamp: >> maximum charge current during precharge phase (typically 20% of battery capacity) >> >> termination-current-microamp (or endcharge-current): >> a charge cycle terminates when the battery voltage is above recharge threshold, >> and the current is below this setting (typically 10% of battery capacity) >> > > We have a client with a board whose battery accepts a maximum of 300mA > for charging. So depending on the battery, we cannot have any charging > current we want. The AXP PmMICs set constant charge current in a range > of 300mA-1800mA, so it is enforced by the charger but needs to be > adapted depending on the battery present in the system. May I ask the capacity of the battery in question? Typically one charges LiPo batteries at no more than 1C. So if it's a 1800 mAh battery, the charge current should be no more than 1800 mA. ChenYu > The AXP PMICs charge battery with constant current (Ichrg) between the > trickle voltage (Vtrkl which is ~3.0V) and the targeted voltage (Vtrgt; > which seems to be the voltage telling the battery is fully charged). > > So if I understand correctly, "my" constant-charge-current would be > located in the charging cycle between your precharge-current-microamp > and the termination-current-microamp as it is the current for the > charging process as a whole. > > See here[1] for the explanation in the datasheet (page 20). > > That would definitely match what is explained in your link for constant > current. > > [1] http://dl.linux-sunxi.org/AXP/AXP209_Datasheet_v1.0en.pdf > > Let me know if something seems odd, > Thanks, > Quentin > > -- > Quentin Schulz, Free Electrons > Embedded Linux and Kernel engineering > http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
