Was the next post ever created?

I’m wondering how to better interpret the scaled voltage from the V+ pin on the V25.

My V25 V+ maxes out at ~1.85 scaled voltage (like Jose) and has sagged as low as 1.54 but also has powered off the USB ports at 1.73 scaled volts.

Is the D+ reading on the USB port equivelent to a voltage reading accross a single LiPo cell of the battery pack? I have an older V72 battery and would be interested in approximating this circuit by attaching A0 to an internal battery lead. Does this seem like a possibility?

It is *complicated*, I tested the whole setup here in my window in Brooklyn, which happens to face the best sun direction. Did all the measurements, reduce the power usage to be less than the 6W panel I was using. The system run for more than a month without problems, the V50 was able to fully charge every day where the sun was partially cloud and would hold for 3 to 4 days on bad days. When I moved it to the remote area, I’m not getting anything close to that in terms of sun. Lots of trees so I get only a few hours a day. I just ordered one of your bigger panels (it’s in the mail) to see if the situation improves. I’m using a witty pi to monitor the voltage but with the scaled voltage I’m getting ~1.35 just before the battery shutdown and ~1.85 at full charge. What I’m trying to do is to re-program the rtc on the witty to run the whole setup for less time to save battery when the battery is running low, hoping that can help me go through cloudy days better.

Hi Eric,
You don’t have to use the INA219, you just need some way to translate the analog reading into a digital one.

Hi Jose,

I would first take a step back and get a good estimate for how much power you consume and produce a day in Watt hours (Average current * voltage * time) vs the expected power production per day. If you have say a 10 Watt panel, you might produce 30 Watt hours per day in the summer, but only 10 Watt hours in the winter depending on your location in the world. We recommend this tool: http://blog.voltaicsystems.com/estimate-solar-irradiance-iot-device/

Any chances I can get a version of this for the raspberry pi? I setup a remote camera powered by your panels and battery. But after a few time it is clear I’m not getting enough sunlight to keep it on on the schedule that I created (from 8am to 8pm). I want to detect that the battery is low and reduce the consumption of the pi (turning it on for less hours). I have a Witty Pi that can read the voltage, so which pins from the USB-C breakout I need to connect to their VINs and GND? The whole system is powered through another USB port. Do I need to power it from the USB-C as well?

Thank you for the reply! Would I be able to get the Power Level of the battery pack without the input, just by connecting a INA219 to the USB C or even USB A. Thank you

It is technically possible to put it on the data pins of the MicroUSB input, but it isn’t a planned change. Hardware changes typically take over a year to propagate into the system.