Hi!
I built 2 Meshcore repeaters out of the Xiao set and have some strange behaviour. I added a 3.7V Li-Ion battery and everything is working fine for about one day. Out of a sudden the devices stop working - a steady red LED is on and all I can do is unplug the battery and plug it in again to restart the device. After this this it works for another day.
Anyone else having this problem? Or, does anybody know, what it means when the red LED is on instead of blinking?
Thanks!
my7 guess would be some sort of timer overflow… the 16 bit timer problem
Strange, a lot of MeshCore repeaters have been built with that set/kit.
What is the battery voltage when it stops working? Fully charged should be 4.2v and the MeshCore firmware won’t boot below 3.3v
It is constantly over 3.9V or 80%. I have 2 identical sets that have the same issue. I also operate 2 SenseCap Solar (that are also built on the Xiao) and the don`t seem to be affected. Could it be the battery that is causing the issue? Or the solar-panel I have attached?
Thank!
So it just happened again - after around 18hrs:
After unplugging the solar-panel it is still not working:
I have to unplug the battery:
After reconnecting it, the device boots normally and shows the following stats:
I would really like to use it as a repeater but I`m not sure if I want to mount it to a pole knowing I have to restart it permanently. 
Hi there,
So , on the Bench I would add a cap to the Battery(+) input something a little big.
Does it always have a USB plugged in when it’s occured before?, This Time?
Kind of indicates to me a Brown out dip, from Transmit power or switching.
Try the CAP and maybe lower the power output see if it makes a difference.
did it come pre-soldered? can we see the battery connection to PCB 
HTH
GL 
PJ 
The SenseCap Solar are nRF52840 PLUS variant MCU’s
Yes the USB is always connected, it is the solar-panel, I 3d printed a minimalistic housing:
It did not came pre-soldered, but I`m mot sure if the soldering is a problem, because I have a second (identical) build that has the same issue.
MeshCore repeater firmware recently added get pwrmgt.bootreason CLI command to show the reason for the last reboot, might be useful. With a battery attached I wouldn’t think there would be an issue with brown-outs unless there’s a faulty connector.
You have soldered to the battery pads under the nRF52 board? Edit: I see you posted photos, looks fine but you’ll have to check your soldering.
It gives me “Reset: Cold Boot; Shutdown: Unknown” which is kind of expected since I had to restart it because it was stuck. Do you really think a bad soldering could cause this issue? I mean if it was not soldered well, wouldnt there be always an issue? It works (and loads the battery via solar) for several hours and then suddenly stops working. First I was thinking about the outdoor temperature but then it worked a full night at -3°C without any errors.
Operational temp of BQ25101 is 0 to 125°C… May be an issue at -3°C?
nice little unit
did you try running meshtastic on it?
Many people are running these in repeaters in Canadian winters down to -40 C I don’t think that’s an issue. I’d pull it apart and power it from a known good USB power adapter only for a while and see if it still has a problem
I will run it on battery only for the next test to see, if the issue comes from the solar-panel of from the battery. If i can’t figure out a solution I will switch to Wio L1 Lite since I have made some good experience with the L1 in my tests. This one does not need any soldering and supports solar-charging out of the box.
Ad Meshtastic: i have tried this first but to be honest, the Meshcore app is far more intuitive, Meshcore feels kind of overloaded, at least for people who are not familiar with the technology. I am currently building up a mesh for a rural community of around 7000 people and we are mounting fixed repeaters on 4 fire departments. Therefor we use SenseCap Solar P1 which work really good. To extend the range of the mesh I wanted to have some cheap “deploy-and-forget” repeaters - thats what the Xiaos where meant for. Well, that turned out to be more challenging than expected.
Sorry I meant disconnecting the battery and running from USB wall/mains power only to eliminate possibilities.
I agree MeshCore is a much better choice for that number of nodes and for reliable message delivery.
Not sure why you’re having problems, there are many deployed here on solar+battery.
If you run out of ideas, try the #hardware channel on the main MeshCore Discord
no i was asking if the same error happens when running meshtastic… maybe it is a software bug in meshcore
For my solar powered XIAO installations, I just use the USB on the XIAO - the solar+battery system is separate. I have found the XIAO charging system is a little on the slow side.
I was going to ask what charge controller you’re using, and making sure the voltage isn’t backfeeding into the solar panel, but it looks like you checked that already by disconnecting solar.
There are some fake Li-on batteries, do you have a capacity tester? You could also weigh the battery, an 18650 should weigh about 45-50 grams
Hi there,
AOK, looks good, nice work on the minimum 
SO couple of questions.
If you only run it on Battery (how long does it last) did you profile it as far as power consumption for your scenerio?
Will it run with only the Solar Panel , NO battery ? (assuming a sunny day)
How many Hours sun do you get in your location approx?
this last fail was after 18 hours and normal system config, Battery and Solar ON.
Can you test it with a battery Bank plugged into the USB-C and connect the battery also, how long before it stops (does it always have the RED RGB led ON ) when it fails , thats a USR LED. Hmmm
The solder is only somewhat sus, unless they are soldered the same way?
which would push me to the configuration.
Solar Panel (BQ25101) in the middle and Battery, a pretty large one at that.
At some point the BQ is feeling the Heat or pressure, maybe unevenly and it latching up or crowbarring ??? Something is up with the Power rails as a result I’m betting.
Any Idea on how much current it operates normally on? How did you size the Battery?
LMK
HTH
GL PJ
Stay at it , your close you’ll figure it out. 
Great walk up & down the troubleshooting ladder.
Also I don’t think you need such heavy wire, I know you just used a pigtail that matched the whopper that comes on the Battery
Recommend operating temperature is 0 - 125 °C, but absolute maximum air temperature operating range is -40 to 150 °C.
