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# BQ24610EVM: Equation of the charge current for the taper mode

Part Number: BQ24610EVM

Hi Team,

Our customer has follow up inquiries related to the E2E thread below.

e2e.ti.com/.../bq24610evm-the-bq24610evm-is-not-charging-the-battery

Also, I would want to know the equation of the charge current for the taper mode. I have another question regarding to the STAT1 and STAT2. Will those two status voltage means anything when the charger is set to taper mode?

Can you also explains the relationship between the SRN voltage, output voltage vs. the charging mode of the battery? I don't quite understand how does the SRN voltage makes the charger into taper mode. Is there a way to get out of the taper mode, and charge at a constant current?

Regards,

Danilo

• Dear Danilo,

There is no equation for taper mode. Taper mode is by the definition the mode where the SRN voltage is held at regulation while slowly lowering the charge current. This is done because once the SRN voltage reaches regulation the actual battery voltage will be lower due to the impedance between the SRN pin and the actual battery. Taper mode ensures that the battery is fully charged and is also known as constant voltage mode.

During taper mode, STAT1 will be on and STAT2 will be off because charge is in progress.

If you charge at constant current, say 1 A, and you cut it off right when SRN reaches regulation, your battery will not be fully charged. Taper mode exists to make sure your battery is fully charged no matter the impedance between the charger and the battery.

Thanks,

Mike Emanuel

• Hi Mike,

Here is the customer's response.

Can you let me know what is the Regulation that you were referring? What is the voltage level of Regulation?

Regards,

Danilo

• Dear Danilo,

The regulation voltage is the programmed battery voltage you are trying to attain. Please see Section 9.3.1 of the datasheet. This voltage is the maximum voltage you want your battery to be charged to.

Thanks,

Mike Emanuel