Post by SDL on May 21, 2017 8:39:09 GMT -8
Hi guys, I’ve recently purchased SunAirPlus for my home autonomous solar powered webcam project.
To test my new toy I connected single 18650 3.7v (maybe 2200mah) battery to the LiPo input of the board and 12v two solar panels connected in parallel with safety diodes stepped down to 5v to the solar panel input via USB meter to see the output voltage and current the whole system draws. To the output of the board I connected my streaming Raspberry Pi.
I left it running overnight expecting at morning having sun on my batteries to see that lipo is charging and RPi is working again (in case lipo died overnight). But I see on the USB meter that with bright Australian sun the board draws just only 90mA and barely can charge the LiPo and if I turn on the output itstops charging the battery at all moreover it starts discharging it trying to keep RPi alive (90mA + whatever battery has). I noticed that SunAirPlus draws very discrete 90mA or 110mA, no more no less.
Just to make sure my solar batteries are okay I connected my powerbank to the 5v output of my step down converter on the solar and saw that it charges with around 500-600mA as I expect.
So I don’t understand what I’m missing here… why board draws just 90mA…
My suspicion was maybe it expects not 5v input from solar but 6v..? Don’t think so though.
Any suggestions are very appreciated!
Levon
Answer:
Hi Levon,
You need more than 5V to get SunAirPlus to charge at the full rate. Remember that the whole charge controller is designed for 6V solar cells. Modifying your circuit to go to 6V instead of 5V will fix the problem. Check it out before hand with a variable power supply and you can absolutely see the dynamics of the system.
When designing a new project, we always use a variable power supply in place of the solar cells to test the system.
Here are some current results from SunRover. SAP0 is the SunAirPlus charging the motor batteries. The batteries are close to fully charged (we have 24000mAh for the motors – a bit of overkill). The 5V power supply of the SunAirPlus board is currently not driving a load, but SAP1 is driving a RaspberryPi 2 and is fully charged.
——–SAP0——–
LIPO_Battery Bus Voltage: 4.21 V
LIPO_Battery Load Voltage: 4.19 V
LIPO_Battery Current: -200.40 mA
Solar Cell Bus Voltage: 5.66 V
Solar Cell Load Voltage: 5.64 V
Solar Cell Current: 201.20 mA
Output Bus Bus Voltage: 4.98 V
Output Bus Load Voltage: 4.98 V
Output Bus Current: 1.60 mA
——–
——–SAP1——–
LIPO_Battery Bus Voltage: 4.19 V
LIPO_Battery Load Voltage: 4.19 V
LIPO_Battery Current: -4.00 mA
Solar Cell Bus Voltage: 5.54 V
Solar Cell Load Voltage: 5.50 V
Solar Cell Current: 462.40 mA
Output Bus Bus Voltage: 4.90 V
Output Bus Load Voltage: 4.94 V
Output Bus Current: 365.20 mA
——–
Hope that helps,
SDL
Thank you, 6v behaves much better!
Continue learning the board! 🙂
Best regards,
Levon