It says its recommended input is 16.8V, not 12V.

The actual operating voltage is about 17 volts for those panels. They call them 12 volt meaning they will charge a 12 volt battery.
Actual charge current under ideal conditions is only about .6 amps.

 

My "12V" solar panel measures 18VDC with no load and produces 12V only when the load does not exceed 188mA.
It can charge a tiny 12V lead-acid battery or it can make up the daily losses by trickle charging a larger lead-acid battery.
When your Lithium battery charges at 16.8V then the current from the solar panel will be close to zero.
Maybe your solar panel is the same as mine?

 

My "12V" solar panel measures 18VDC with no load and produces 12V only when the load does not exceed 188mA.
It can charge a tiny 12V lead-acid battery or it can make up the daily losses by trickle charging a larger lead-acid battery.
When your Lithium battery charges at 16.8V then the current from the solar panel will be close to zero.
Maybe your solar panel is the same as mine?

In advance thank you all for taking the time to help. Question now that I have; do I need a bigger solar panel with a higher voltage?

 

The trouble with a solar panel is that its voltage changes a lot and is too high or is too low for your BMS.
Maybe you use a higher voltage and higher current solar panel and a solar controller that keeps the voltage correct.

 

The trouble with a solar panel is that its voltage changes a lot and is too high or is too low for your BMS.
Maybe you use a higher voltage and higher current solar panel and a solar controller that keeps the voltage correct.

Could I use a dc-dc setup converter to boost the voltage to get a constant 16.8 volts ?

 

I would use the converter to power the W1209.
Below is the setup I would try. The Solar Panel charges the battery and powers the W1209 when there is sufficient daylight.

 

I would use the converter to power the W1209.
Below is the setup I would try. The Solar Panel charges the battery and powers the W1209 when there is sufficient daylight.
View attachment 228877

Okay I like the setup and I will try it. Now for the D1,D2,D3 what diode are you using?

 

what diode are you using?

1N4001 should be fine.

 

1N4001 should be fine.

Great I have a few of those laying around. I appreciate the expertise. I want to throw this out on the table too see what you think about removing the 12v solar panel and adding a 18v solar panel with a step down to add more power for the charging around 16.8volts. Also I could still wire it per your diagram shown. Learning more and more everyday.

 

The normal operating voltage on those 12 volt panels is about 17 volts. I don't think you need a higher voltage panel. I would set up the 12v panel and get some voltage readings.

 

The normal operating voltage on those 12 volt panels is about 17 volts. I don't think you need a higher voltage panel. I would set up the 12v panel and get some voltage readings.

When I get home today I’ll get the panel setup for some more testing and see what it’s producing then get back to you. Thank you