Sunday, April 9, 2017

A Slow Sunday

More boring stuff here. I had a really hard time finding a flat, serial communications cable. That's the gray cable with the red trace near the center of the picture. The flat cable is needed so I could reinstall the cover on the Tristar charge controller. Back in the "olden days" when every computer had a telephone modem, serial cables were available everywhere. Even at Fred Meyer. Not so anymore.

Another potential project is making an enclosure for the micro-computer pictured on the right. It is another Raspberry Pi 3 model B with a 4" LCD touch screen. It is also running Raspian, a Linux variant, with the display drivers from Waveshare. I had picked the screen a couple of years ago but couldn't get it to work with the version of hardware I had. I found it again and decided to take another shot at getting it to work. Even the touch screen works though it needs a stylus to be useable.

I'm thinking of making a simple information page with just the basics. Maybe battery/array voltage, watts being produced and battery temperature which should match outside temperature most of the time. Maybe some color to represent the control state i.e. bulk, absorption, float or night. And possibly some buttons to bring up individual graphs. Then mounting this somewhere in the living area. Not sure yet.

Today was the first really sunny day that we had in quite a while. You can tell from the flat line on the power production graph for today. The drop at around 2:30pm was not from clouds but the batteries reached their absorption voltage and only enough current was sent by the charge controller to maintain that voltage. It stayed in that control state until the sun started to disappear behind some trees at 5:24pm. I even boiled a pot of water this morning to consume some power. 1.75 liters used 16 amp-hours and drew 122 amps from the battery through the inverter. That's more than anything I've tried so far.

I also created another RRD that only gets updated once per day at 11:59pm. I'm storing the amp-hour produced to date from the charge controller. From that, I can graph daily production. It's a boring graph right now as it has only one data point. 


  1. I look forward to checking out all these doodads in person this summer RichardM!

    1. I'm still not sure of the one with the touch screen. It seems to use a lot from the small processor so it runs kind of hot. Just using the iPad or phone to connect to the other RPi monitoring the controller anytime you are interested may be easier.