STEVAL-ISV019V1 and pv cells

[nikhil_vohra]

Hi !

I've the above eval board and wish to charge a 3.7V Li-ion 1500mah battery using PV Cells.

When I connect the PV Cells to the input and check the output (bat-line), we do see 4.2V. Then when we connect the battery whose voltage is 3.98V and let it charge for over 30 hours, we notice the voltage of the battery has not increased. 

Please advise, Thanks in advance. 

[Peter BENSCH]

Welcome @nikhil_vohra, to the community!

What is the specification of your PV panel?
What is the voltage at STORE (CN4.1) and VBATT (CN2.1) when you connect the battery?

Regards
/Peter

[nikhil_vohra]

Hi Peter,

Please find our response. Thanks & Regards,

Nikhil

[Peter BENSCH]

Well, it is a somewhat small PV panel. Even if two are connected in parallel, 427 lux is probably not enough to generate meaningful charging power. That was the reason why I asked about the voltages before and after connecting the battery. You can also check whether a measurable current flows into the battery at all?

/Peter

[nikhil_vohra]

Hi Peter, 

Please find our readings with and without battery connected to Eval board:

Battery open Voltage: 3.86V

With no battery connected to Eval board:
CN1=1.00V, CN2(1,2)=4.2V, CN4=4.2V

With battery connected to Eval board:
CN1=0.93V, CN2(1,2)=3.86V, CN4=3.86V

Thanks & Regards,

Nikhil

[nikhil_vohra]

Hi Peter,

Futher to above, attached current and PV_cell input for reference.

Thanks & Regards,

Nikhil

[Peter BENSCH]

This confirms what I already suspected: the output voltage collapses to the battery voltage when the battery is connected because there is not enough energy to supply sufficient current. The average value of the current of 49.62µA is perhaps just enough to compensate for the self-discharge of the battery.

If you want to charge sensibly, you should connect a considerably larger PV cell and illuminate it sufficiently - preferably with full sunlight.

Good luck!
/Peter