BQ24650: Battery Charging issue using BQ24650

Vishal,

What is the MPPT voltage and Voc (open circuit voltage) for your solar panel?

Thanks,

Ning.
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Hello Ning,

Thank you for inputs.

What is the MPPT voltage and Voc (open circuit voltage) for your solar panel?

- MPPT voltage is varied between 1V to 1.3V depends on whether and Solar panel Voc voltage is 7.0V.

if possible Kindly explain brief of MPPT voltage requirements and how set MPPT voltage for BQ24650 ic.

Thanks Regards,
Vishal Mistry
Embedded Hardware Engineer

Dear Ning,

Is the 7V Voc spec from the solar panel datasheet or by your characterization? 

Yes,True 

Solar Specification is below 

- Solar Cell Type: Monocrystalline
- Max Power: 6.0W
- Solar Cell Efficiency: 18-19%
- Open-Circuit Voltage: 7.0 V
- Max Operating Voltage: 6.0 V +/- 10%
- Short Circuit Current: 1080 mA
- Max Solar Current Draw: 980 mA +/- 10%
- Operational Temp. Ranges: -20F to 140F (-30C to 60C)

Please note that Voc and Isc vary with the light conditions. The Voc used for the BQ24650 design should be the characterized Voc based on your specific light conditions.

I observe the Solar voltage open circuit voltage Voc=6.7V when solar panel mount in circuit with load at that time voltage is reduced Vsc=6.2V and then by charging 3.75V battery solar voltage is reduced to 5.5V also, the Isc vary with light conditions and voltge is fix 5.5V. The charging current is 200mA.

We tested another approach using SMPS Circuit with battery charging voltage is reduced by only 1V and charging current is 900mA. 

Kindly solve query why the solar voltage is reducing more by charging a battery and how to improve solar charging current.

one more query is regarding MPPT voltage. what is minimum and maximum voltage can be applied to this pin?

Let me know if you require more information.

Dear Ning,

Thank you for information.

We tested one approach, The result is given below.

Now We set 1.45V MPPT without battery voltage then we got 500mA appx charging current rate so, kindly tell me why Voc with circuit load and battery charging is varying with MPPT without battery voltage?

we need one more help we observe one thing when we measure charging current using a multimeter(fluke 17B+) or UART terminal window then we observe differences in charge current is appx 50-100mA

Kindly guide why the difference is occurring in both. 

Let me know if you required more information regarding this  

Dear Ning T,

Thank you for your inputs.