I was looking around the internet for ideas for a solar powered Meshtastic node for a remote area project I am working on when I found this video on youtube:-
It describes modifying a solar powered outdoor LED light for use as a remote Meshtastic node.
I looked in my local Bunnings but they have been out of stock for a while. Today they were back in stock and they have actually been upgraded from the one in the video.
They now include 2 18650 cells in parallel for 3600mAH at 3.7 volts (3000mAH in the old one).
It is a 5 Volt panel. Everything is well sealed against weather.
I reckon this would be a real time saver for such projects. And only $39.90 !
I think the DFR0264 solar LiPo charger available here is all that is needed to replace its own circuitry.
Ian
I’d say you could probably get away with using the circuitry from the light and just remove the LED from it, hard to judge from the photos but it looks like you’d be able to get something like XIAO ESP32S3 for Meshtastic & LoRa | Buy in Australia | SS102010611 | Core Electronics in the LEDs place and it should be pretty well weatherproof.
the light. Someone with more knowledge than me might get something from the picture.
I actually put it out in the sun for a few hours and it looks like the charging cuts off at 4.2V which is encouraging. They seem to have gone to a lot of trouble with waterproofing for a cheapo company like Arlec. Nice silicon rubber seal around the electronics. And it is all put together with screws so easy to disassemble without breaking anything. I just bought a second one as I was impressed by its potential for remote area projects. Can always use it as originally intended if it doesn’t get used for a project.
Yes I read somewhere that the ESP32 devices were a bit power hungry. As far as I can see the RAK Wisblock is recommended as using the least power but they are relatively expensive.
I don’t know how the Pico/Waveshare LoRa combination compares. (which is what I have).
I also wonder about the maximum charge rate of 100mA. Doesn’t seem like enough to me to cope with recharging a depleted 3600mAH battery when there might only be 5 or 6 hours of good sunlight per day in the winter.
As a solar panel is at its best when facing the sun directly and the sun moves at 15º per hour good luck with the 5 or 6 hours bit. There might be graphs published somewhere showing effective output v sun angle but I have not looked. Don’t forget the vertical angle has to be considered as well.
Cheers Bob
I did some long time testing with my one, being that its an ESP32-S3 it is hungry. I found that it would idle around 60mA, when transmitting it would jump up to around 120mA.
Your mileage may vary depending on how many messages you’re transmitting.
Hi Robert93820,
Yes as someone who used to have a solar power installation business, I am very aware of the requirements and limitations
Hi Liam. That is good news. I look forward to seeing the additions. Hopefully the Wisblock will be one of them. And hopefully the prices will be more reasonable than those from other suppliers!
I have just set up a crude test rig for the solar power light plus Pico/ Waveshare LoRa using Dan’s suggestion of using the charging circuit in the solar light without additions or alterations.
I just soldered leads to the battery connection on the board and plugged them into the power connector on the LoRa board. Seems to be working well but I am monitoring the voltage seeing I know nothing about the charging specs for the solar light.
I will run it overnight to see what happens.
I did a current measurement and at the time I checked the Pico/LoRa combination was drawing 34 mA. No OLED, no GPS just a bare node.
I have just completed my first effort at converting this solar powered light to a solar powered Meshtastic node. I learnt a couple of lessons for next time but generally I am pretty happy.
One lesson was that they have actually used silicon rubber insulated wires. While they are very time durable the insulation is quite delicate if you are poking around trying to free them from the silicon sealant they used. That is why you can see insulation tape applied where I damaged the silicon insulation. Next time I’ll know better.
I used the circuit board which came in the light for the charge controller as it seems to work well. I won’t really know until I’ve put it outside for longer term testing. All I did was remove the LED light and connect the power cable leading to the Pico/Waveshare directly to the battery connection on the charge controller board. The right-hand box is Jiffy UB5 from Jaycar with a clear top so I can see the lights on the node electronics without opening it. The UB5 boxes come in black, grey and clear. As the UB5 boxes are not sealed I will seal it with Loctite MR 5923 Aviation Gasket Sealant which does not set or go hard so the box can be opened when necessary. I plan to add a “verandah” of aluminium adhesive tape (Bunnings have it I think) so that water does not directly fall on the electronics boxes. The left hand box is an old car part box I had lying around. It contains the charge controller board. It could probably have fitted in the other box but I thought if there is going to be a source of heat that is probably it so I put it in its own box. I have sealed around cable entry points in the boxes with SikaFlex Premium Car Body Sealant which is incredibly tough once dry (fairly quick). It is also very strong glue so the boxes are stuck to the light with it as well.
The antenna is the Seeed 2.6 dBi SMA male 915 MHz 195mm available from Core. It fits as a direct replacement for the tiny antenna that comes with Pico LoRa kit.
That looks like a nice bit of kit you have made there! The antenna looks like it was designed to live there all along!
I love the attention to detail when thinking about how you are going to service this long term. I’m sure a lot of us can relate to putting together a nice compact project, only to have something go wrong and not be able to easily fix it without completely taking apart the whole thing.
This looks awesome! Keep us updated with how this goes as you with some longer-term testing.
Yesterday I put the solar node outside in a clear position to give it its first run overnight.
Today was a cloudless day so I got to see a good test of recharging.
I’m pretty happy with the result. The minimum voltage just before the sun hit the panel at about
7-30 AM was 4.13V or 95% by Meshtastics estimation. By about 9-15 AM the voltage had reached 4.28 V which seems to be the controllers cut off point. For the rest of the day the controller kept it between 4.18 and 4.28 V.
The next few days forecast is either partly cloudy or cloudy so that will be a much more significant workout but I am encouraged that 14 hours between sunset and sunrise only used 5% and that was replaced very quickly so I have a feeling it is going to work well. I’ll let you know what happens.
After 4 nights and 3 days of heavily overcast weather when virtually no charging occurred the voltage dropped to 3.93V or 74% by Meshtastic’s estimation. Considering the time of year I am pretty happy with that. Then after a couple of days of partly cloudy weather it was close to fully charged again. Pretty encouraging I think.
I thought I should finish this by reporting a minor downside.
If you look at the attached screen grab from the Meshtastic Android app you can see that though the charge controller that comes with the light works OK, it does not do the constant voltage phase that proper Lithium battery chargers do. It reaches a little over 4.2 volts, stops charging and then resumes charging at a little under 4.1 volts. While ever the sun shines it continues this cycle which never fully charges the battery and probably reduces it’s life. So ideally it would probably be better to replace the charge controller with one of the proper ones Core sells. There are quite a few of these and I am not sure which would be best. Maybe someone else might recommend one.
The long gaps are where my phone was off overnight.
One possible option based on the what limited information I could find about the solar panel is the Sunflower: Solar Power Manager 5V.
It’s a compact solar charge controller designed for 3.7V Li-ion/LiPo batteries. It supports 4.4–6V solar input, features MPPT charging, delivers a regulated 5V output (up to 1A), and includes protection against overcharging and reverse connections. It also supports USB and solar charging modes with input prioritization. Note: it does not include over-discharge protection, so using a battery with built-in protection circuitry is recommended.
Thanks for that Ryan. I actually had a look at the product wiki that you have a link to and it disagrees with the note you have about over discharge protection. The photo you show says version 1.1. The wiki says version 1.1 DOES have over discharge protection. Which version are you actually selling?
Below is info copied from the wiki
Version History
V1.0: It is highly recommended to use a 3.7V lipo battery with protection circuits to improve battery safety.
V1.1(Newest): Battery (BAT IN) overcurrent and overdischarge protection is added to improve battery safety. It can be use for 3.7 lipo battery no matter it is packed with protection circuits or not.
Nice catch! I’ve checked the warehouse, and the good news is we do have V1.1. You’re right, so please ignore my previous comments about battery protection. I’ll update our website accordingly.
Glad to help!
I’d love to try one of these but I have just done an order so it will have to wait I guess.
I probably would have already ordered one but the incorrect warning put me off!
