Mastodawn

Probably I have fixed an issue with my Heltec V4 Meshtastic node - sometimes it was rebooting randomly, often while sending a message or doing a traceroute.

I assumed it was because of a voltage drop while transmitting, maybe the BMS undervoltage protection board adds some current limitation or the cables to the battery are too long and thin. At least I have read somewhere something like that could be a reason.

Grabbed my box for electronic components, found a 470 µF capacitor and soldered it between the Heltec board and the power switch.

Until now: No sudden reboots anymore!

#Meshtastic

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Bruno PY2TOZ 2d ago

@finn What a coincidence! I'm trying to tackle this very issue right now. My #heltecv4 reboots on TX if the battery is under 3.7V and power is set to 22 dBm+.

I tried to insert a 1000uF cap just like you did, but it didn't work. I measured the voltage sag and it takes way longer to recover to baseline, whereas the capacitor can handle it just for a fraction of a second.

I wonder what I'm doing wrong... My temp solution was reducing TX power, which negates the only advantage of having a V4 😮‍💨

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Finn 2d ago

@py2toz Oh, that sounds bad, I don't have any idea for this. I guess I was lucky, added the capacitor and it worked.

Also I didn't mease anything. A multimeter probably is too slow, right? How did you measure the voltage drop?

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Bruno PY2TOZ

@finn Yes, multimeters are usually slow. I'm using a bench power supply whose ampmeter is a bit faster. But maybe (certainly) an oscilloscope would be more appropriate.

I'll try another capacitor when I have the chance. Maybe I was just unlucky (or my Heltec unit has an entirely different issue 😅).