Charging question - Newbie

Hi there!

I believe that everything is working well. The -10.0ma value means your battery is CHARGING! You rock!

Test this by shading your panel and watch the value turn positive (but you are only drawing 3.6mA so it won't be much - 4 or 5ma).

BP

Also, I tried to find the max input for the SunAirPlus but all I can find is that is "prefers" 6v input. Can it take 12v at 2A? If so, is there any benefit to removing my step down converter? Thanks!!

cz461,

This is not a stupid question! The reason your battery is not charging up is that you are consuming a bunch of current. Look at your Output Current 3.

If you want to compare amount generated versus amount consumed, remember to not compare currents, but compare power.

Power = Voltage * Current

or Power = Voltage * (Current in mA/1000)

That will tell you how much power you are generating and how much you are consuming.

You battery is not fully charged because you are using a bunch of power!

Best regards,
BP

cz461,

Boy, we don't know what your step-down transformer is doing. There are many possibilities. First of all, a step down transformer does not look like a solar panel to the controller circuitry, so the controller circuitry may be limiting your power coming off of the step down transformer. And since this is DC, it is not just a step down transformer (transformers only work on AC) so there MUST be other circuitry involved.

What exactly do you have and give me a link and I'll take a look.

BP

Well, as I said, these converters don't look like solar panels to the charge controller.

The second converter *might* work better if you set it for 5V or maybe 5.5V. NOTE: You can't charge LiPo batteries with that device. It would be dangerous.

Putting a bunch of 6V Zerner diodes could reduce 12V to 6V, but you would dumping a lot of current through them, so I wouldn't recommend it.

With SunAirPlus, you are better buying 6V Solar Cells.

We may be bringing out a 12V version of SunControl in the future. We are looking into it.

BP

Got it installed and adjusted. Looks better now. If I need to, I will just have to find a 6v panel I suppose.

------------------------------
LIPO_Battery Bus Voltage: 3.80 V
LIPO_Battery Shunt Voltage: -37.88 mV
LIPO_Battery Load Voltage: 3.76 V
LIPO_Battery Current 1: -378.80 mA
Solar Cell Bus Voltage 2: 5.19 V
Solar Cell Shunt Voltage 2: -82.76 mV
Solar Cell Load Voltage 2: 5.11 V
Solar Cell Current 2: 827.60 mA
Output Bus Voltage 3: 4.91 V
Output Shunt Voltage 3: 35.08 mV
Output Load Voltage 3: 4.95 V
Output Current 3: 350.80 mA
------------------------------
LIPO_Battery Bus Voltage: 3.80 V
LIPO_Battery Shunt Voltage: -36.52 mV
LIPO_Battery Load Voltage: 3.76 V
LIPO_Battery Current 1: -365.20 mA
Solar Cell Bus Voltage 2: 5.19 V
Solar Cell Shunt Voltage 2: -81.68 mV
Solar Cell Load Voltage 2: 5.11 V
Solar Cell Current 2: 817.20 mA
Output Bus Voltage 3: 4.91 V
Output Shunt Voltage 3: 35.08 mV
Output Load Voltage 3: 4.95 V
Output Current 3: 350.80 mA
------------------------------
LIPO_Battery Bus Voltage: 3.80 V
LIPO_Battery Shunt Voltage: -38.40 mV
LIPO_Battery Load Voltage: 3.76 V
LIPO_Battery Current 1: -384.00 mA
Solar Cell Bus Voltage 2: 5.19 V
Solar Cell Shunt Voltage 2: -82.80 mV
Solar Cell Load Voltage 2: 5.11 V
Solar Cell Current 2: 828.00 mA
Output Bus Voltage 3: 4.91 V
Output Shunt Voltage 3: 34.88 mV
Output Load Voltage 3: 4.95 V
Output Current 3: 348.80 mA

Thanks again for your assistance. I've come to the conclusion that the RPi 3B+ is just too power hungry to be reliable in this scenario. After running a bunch of calculations, it seems that I am generating around 36wH over a 10 hour direct sunlight period (outside of this period is about 2 hours of twilight on either side which doesn't result in a net gain of power). During the 10 hour day period, I'm using about 16 wH for the load and during night/twilight another 15.5 so I really only have a net of 4.66 wH over roughly a 24 hour period. I'm finding this is causing the system to just run itself down over two or three days, which gets worse with any cloudy weather.

Even with reducing the power consumption on the pi (disabling ethernet & usb hub, LEDs, HDMI, etc) it's still not enough and I think I will need to swap the 3B+ for a Zero W.