This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
Hi ,
We are developing a Handheld device.
We are using BQ25790EVM for charging a Lithium Ion Battery of 3.7V .
We are able to read the battery voltage correctly.
But while charging the Battery terminal voltage is increased by charger output.
How we can know the battery voltage/level while charging.
Battery does not have any voltage sense pins other than BATP and BATN.
Below is the schematics
Thanks and Regards,
Dhiraj Phadte
Hi Dhiraj,
The charger has an ADC that you can use to report the instantaneous battery voltage and charging current. The charger does not have memory and so cannot perform gauging function like a battery gas gauge.
Regards,
Jeff
Hi Jeff,
We are using ADC to read the battery voltage and using that to report battery level on LCD screen.
When Unit is operating on Battery it reports correct voltage.
But when we are charging the battery Voltage is higher that actually battery voltage. So battery level reporting is wrong.
How we can address this issue. We understand that when charging charger providers higher voltage at battery terminals for charging.
How we can read the battery voltage during charging accurately.
Regards,
Dhiraj
Hi Dhiraj,
The charger does not provide a higher voltage while charging. It is operating as a current source until the voltage sensed at BATP = VBATREG. The voltage sensed at BATP = battery cell voltage + Ichrg*(Rboard+Rconnector+Rcable+Rprotectorfets+Zbattery). It's difficult to know Zbattery without a gas gauge but you can measure board, connector, cable and protector FET resistances and then substract the voltage drop created by those resistances. Moving BATP as close as possible to the battery pack with help eliminate Rboard and possibly Rconnector.
Regards,
Hi Jeff,
Thanks for information. We will implement correction in our firmware.
Regards,
Dhiraj