Good evenening,
I bought one of your products, the SparkFun Sunny Buddy - MPPT Solar Charger, but I need some clarification regarding the set-up and the assembly of the system.
My solar panel is expected to have a maximum output voltage of 22.2V, and an output voltage when at MPP Vmpp of 15.4V. Why do I have to adjust the potentiometer until V_set is 2.8 V?
Secondly, is it possible to connect two charge controller in parallel?
I have two different solar panels with different output voltage, so I bought two charge controller; how can I connect the two batteries?
The Sunny Buddy is rated for 6-20v, so 22.2v is going to cause problems without something stepping it down first.
This section "You’ll want the voltage at this node to be at 2.7V when the solar panel is at the “knee” voltage we discussed in the Why MPPT? section above. Some solar cell manufacturers may give you this information; the manufacturers of our panels, however, have not. You can either take the hard road and characterize your cell (ick) or take the easy road and make an educated guess that the MPPT point will be at about 90% of the voltage you see when you’re in full sun.
To find that point, plug your solar panel into the Sunny Buddy, but don’t put a battery or load on it. Measure the voltage from the “SET” pad to the “GND” pad next two it, and tweak the potentiometer until that voltage is about 3V. At that point, the Sunny Buddy will draw current until either 450mA is going to the load and the battery or the solar cell voltage is 90% of its full-sun open-circuit nominal voltage." is setting the input current limit for charging the 3.7v LiPo, you would simply perform the same steps @ 90% the given max voltage of your panel
Thank you very much! I checked it up and now the two chargers work well. Do you know if it is possible to connect the two chargers in parallel in order to charge a LiPo Battery (3.7V 2000mAh)?