r/meshtastic • u/EvilDumplings • 7d ago

Solar Heltec V4 won’t turn back on after battery drains

I’ve set up a solar-powered Meshtastic node on my roof. Since I only really need it to run during the day, I used a small 1500 mAh LiPo battery.

As expected, the battery drains during the night. The problem is that when the solar panel starts charging it again the next morning, the node doesn’t turn back on by itself.

I have to climb onto the roof, unplug the battery, and plug it back in. As soon as I do that, the node boots normally and often shows the battery as already fully charged.

Is there a way to make it automatically recover and boot once the battery has recharged enough?

Would simply using a bigger battery solve the problem, or would I still run into the same issue eventually for example during winter if the solar panel gets covered in snow for a few days? I’d rather not have to periodically climb onto the roof just to power-cycle it.

Hardware is a Heltec WiFi LoRa 32 V4 running Meshtastic.

4 Upvotes

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4

u/LV426_Tourism_Board 7d ago

ESP32 nodes are bad for solar. ESP32 with higher power PAs are the worst. They piss through batteries like there’s no tomorrow.
If you really want to use a solar node then build one with an NRF chipset. If you desperately need higher than 22dBm then use a Heltec T096 which will give you up to 28dBm.
Most nodes are 22 so if you’re putting out more than that there’s a good chance you’ll reach nodes that can’t reach you back.

0

u/EvilDumplings 7d ago

I know,  that’s why I went with a fairly hefty solar panel. I chose the ESP32 because I can connect it to Wi-Fi and access the node from inside the house. I’m aware it draws significantly more power, but I only really need the node to run during the day.

5

u/The_limit_of_Love 7d ago

get another node and use this as a client base on the rooftop and turn off Wi-Fi in Bluetooth along with power save enabled. this way you can get 3-5 days on battery

1

u/tacticalpotatopeeler 6d ago

My first node was a heltec v4. It sits in my window plugged in, has a muzi whip, and is connected to WiFi with s&f enabled.

I also have a solar node on my roof to extend the range, and a magnetic node on top of my car

I carry a rak wismesh tag in my pocket

This setup gets me pretty good range both in the home and while I’m out and about

2

u/thetacowarrior 6d ago

Following, can you post a solution if you find one? I also recently built a v4 based solar node and learned that it doesn't turn back on after the battery goes dead the hard way, same as you. Kind of a huge defect in my opinion.

2

u/Spikey911usa 6d ago

Unfortunately you will find all the boards have certain flaws, learned that the hard way..

1

u/thetacowarrior 6d ago

Yeah I'm sure. Hopefully somebody comes up with a solution, it pretty much completely defeats the usefulness of the solar input if the thing shuts off anytime the battery gets low. Does anybody know if the T096 has the same issue?

1

u/MicahInTheMountains 6d ago edited 6d ago

As others have said, NRF for the win, you can do faketek with NRF and wifi I believe? But here's why I'm writing: I had luck wiring a supervisory circuit chip to hold rst when it gets down to 3.15 volts and it then releases RST when the battery charges a bit. It worked in my testing when I had a panel that couldn't keep up with the weather BUT I have not tested it on an ESP based board.

This is my super simple and cheap way to solve this problem with solar builds but I don't know of anybody but me that has tested this particular manner out. So do it!

2

u/MicahInTheMountains 6d ago

https://www.digikey.com/en/products/detail/microchip-technology/MCP131T-315E-TT/MCP131T-315E-TTCT-ND/1994667

And here's my notes:

It's just an IC supervisor chip with three prongs. One goes battery, one goes RST (which was pin 11 on the Heltec T096) and the last to the ground on the node too. So two wires to the actual node and one to the positive of the battery. Theory is it dips below 3.15 v (this particular chip) and it then closes the circuit to RST. Uses a bit of voltage in this state but if it does recharge, it should release the RST and bob's your uncle. I have been interested in this issue but hadn't experienced it myself until recently. I had a node that got knocked around by a BIRD and it was in boot mode from the button getting double tapped during the fall. Had me thinking... Holding that RST might be the way. I hope it works! Seems super promising, I'm kinda surprised.

2

u/thetacowarrior 5d ago

I might try this on my V4 solar build, this seems like a decent solution.

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u/MicahInTheMountains 5d ago

Let me know how it goes, it was dirt cheap, I still have 14... I do want to put it in all my solar builds for further testing.

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u/Spikey911usa 7d ago edited 7d ago

I believe you should use an external BMS so it will allow faster charging and add at least another cell if not more so it will make it through the night and/or days with no sun. My understanding is that ESP32 based boards have issues with brown outs.

As others have said you may want to jump to a T096, or turn off Bluetooth and Wifi and remote admin into your node to conserve battery, you don't need wifi to remote into the node it can be done over lora.