Hi there, someone on Discord asked me to post this here when it was done. It’s my latest solar enclosure based around a 3 watt solar panel and the RAK19004 Green Power module.
What I like about this one is that it can be used for lots of different solar projects. The carrier plate on the bottom can be customized to hold different components like a different board or battery. The usable interior space is 100x100x28mm.
This looks great, nice work! Do you really get 8 days with the 2,000 mah battery?? This is way more efficient than what I’ve seen on the Heltec or tbeam.
Yeah, the RAK has super low power consumption. It’s about 10mA without a GPS. With a GPS it’s around 50mA. TBeams are power hungry at around 100-120mA. This is more a comparison of the nrf52 and the ESP32.
I messaged you about this unit over on Etsy this morning, I’m wondering how it reacts to a dead battery and how it handles super cold weather. I’m in Michigan and we get many cloudy days in a row and we also can experience below zero temps for a few days in a row. Will it self recover? I don’t want to have to climb a 60ft tower to bring it back to life.
Hi Dan, I saw your message on Etsy but I will reply here for others. The unit will come back to life without intervention if the battery drained all the way and the device shut off. So, you’re good there.
However, cold temperatures are a concern for lithium ion batteries. Charging a li-ion battery below freezing could damage the battery unless the charge rate is quite low (0.02C charge rate). I’m aware of this limitation and working on a solution that will allow safe charging at -40 degrees using a different type of battery, LTO (lithium titanate oxide).
I’m building a custom battery charging board for LTO batteries so we can take advantage of their great thermal performance. I’m probably 2-3 months out from having this produced and integrated into this 3W Solar Base Station. I will also offer the charger for sale by itself.
Nice! Yes, I’m working on the LTO solar base station. I have v1.0 of the charger board in hand. There were some critical issues with the first version so I’m updating the design. I have all the parts selected and the enclosure designed and tested. The only thing left is the LTO charger board. I’m currently working through the redesign for v1.1 to make it more useful and reliable. This new version is going to have a lot more capabilities. I’m expecting it to take a couple months until I have the new chargers.
I’ll make an announcement on Discord and here once it’s complete.
I also live in Michigan and want a solution to be on my antenna tower (N8VY). I have 1500 watts of solar for my HAM radio backup and on our frequent cloudy days get less than 100 watts out. Michigan is the 3rd cloudiest state. This is hard on my solar greenhouse as well.
I am very new to Meshtastic and just ordered 6 boards from Ali Express. I will have time to learn before those arrive. This is also useful for my home automation. I already use MQTT and Wifi to mesh my farm buildings, but Meshtastic can be an improvement to what I can reach (and no power buildings and field locations.
All this is vry interesting.
The new Multi-Chemistry Solar Battery Charger and Sensing Voltage Regulator are done! We now have a fully functional LTO solar charger that is compact and very efficient. It’s paired with a buck/boost regular to provide stable output voltage. There’s a lot more to say about this module so I will upload the features and capabilities as a photo.
I also updated the 3W Solar Base Station that is linked at the top of the thread. It supports the new charger module and LTO batteries (and other improvements). You can follow that link for the updated version.
The charger module sold out in less than a week so I have more ordered and expect to receive them in 4-5 weeks.
Yeah, that’s a Mini Sensor Breakout module I had made. It fits into a sensor slot and provides access to two GPIO and I2C. The base board has an I2C header so I don’t actually need to use the little breakout. I just do that because I like to keep the base boards clean (not directly soldered to). It also makes it easier to do all the solder prep ahead of time.
The Sensing Voltage Regulator (part of the MPPT solar charger module, purple boards) includes an INA3221. It’s a 3 channel voltage/current sensor. It reads battery and solar voltage/current and will report that to the Meshtastic firmware. Those readings can be sent over the mesh as telemetry so you can monitor your solar node remotely.
Any chance of a schematic for that MCSBC-SVR board? I’m thinking about trying to make a simpler version that just does 2S LTO and it’d be handy to know how yours works, but mostly I’m just curious about it. Would definitely like to buy a couple when they’re available as well.
Also, do you mind if I ask where you’re getting your LTO batteries? I’ve noticed them tremendously hard to find.
