I have really been enjoying the videos. Iv been refreshing my electronics knowledge (with lots of “gee, i didn’t know that” and “so that’s why that happens” moments). I wanted to share a little project of mine an ask if anyone had any advise about the solar system.
This is my marine robot, Nyx. Nyx 1 was a solar panel on wheels. Nyx 2 is my prototype of a marine exploration robot and Nyx 3 will be a bigger better version which will hopefully be able to swim long distances.
https://twitter.com/NyxRobothttps://www.youtube.com/watch?v=nUwcMUmB27I
The electronics are a Raspberry Pi A+, GPS module, compass, 4G internet and HD camera. This all uses very little power, measured in the hundreds of milliamps. But the propulsion is from 2 Blue Robotics T100 marine thrusters. They are rated up to about 130 watts each (admittedly, this is where they are least efficient). I’m looking to build a solar system which is as efficient as i can make it. The system on Nyx 2 is a 40 watt marine panel, a small simple charge controller and a very small battery. In fact, I’m surprised iv been able to drive the thrusters as fast as I have with this. In the video they are at about 50% power and the ESC claims they draw about 5 amps each. But at the end of the day, I’m trying to build a small system that delivers as much power as possible. And then Nyx will regulate his thruster speeds to accommodate that.
I’m thinking i need to build all the electronics under the panel and use a 80-100 watt panel on a board which is perhaps a little longer - up to the length of a surfboard.
The electronics require a 5 volt supply. I was thinking a simple regulator, perhaps with a large capacitor to help protect against brown out of the thrusters spike the load.
I’ll need a MPPT charge controller and it would be as small as possible. My concern with running the load directly across the battery is, how would thrusters drawing lots of current effect voltage and battery charging, if voltage drops below 14 volts? Iv noticed that some charge controllers have the separate load connection, but will cut the load to protect the battery. That’s the worst case scenario for me. If the CPU loses power it’s game over
I could use a voltage divider and an ADC so the software can keen an eye on the panel and battery voltages.
And then there’s the batteries. The lighter and more compact they are the more i can use. But on the other side of that, Nyx 3 will need a keel - to keep it upright and to help it maintain forward momentum. So i was thinking of building the batteries into a keel. So they weight would be useful, up to a point.
The thrusters are rated to 30 volts. I’m using 12 volts, but maybe there is a case for a 24 volt system?
The goal would be that it could remain constantly in motion, traveling at speed during the day. Slower overnight, based on battery levels, or just hold position if power it too low.
Anyway, lots of challenges. But lots of fun.
