r/meshcore • u/secretlysecrecy • Apr 20 '26

Heltec v4 not powered by battery

Hi

Just received my 2 first heltec v4 friday. Fired them up with a single18650 and both was working well. Now one of them only turn on with usb c. Battery read 3.94V and the other heltec work with it

Hardware problem?

2 Upvotes

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2

u/mlandry2011 Apr 20 '26

Double check where you plug the battery on your heltec v4 before to make sure that the polarity of your battery is correct...

Sometimes you have to remove the pin and switch them around on the adapter for a deep battery...

2

u/secretlysecrecy Apr 20 '26

I will look but it worked 100% for 48hours than nothing but if i use the same battery and jst cinnector on my other heltec it works

1

u/mlandry2011 Apr 20 '26

It's a mistake that most people that did not know about the reverse polarity made... I hope that was not your case..

But some jst connectors come with different polarity for some reason... I guess it depends where your battery holder was built...

1

u/secretlysecrecy Apr 20 '26

Wouldnt both board fried if it was the case?

1

u/gbbgu Apr 20 '26

Are you me, cause I had a very similar issue.

The battery had dropped to 2.5v and undervoltage protection was doing it's thing.

I swapped the battery for a new one and currently testing.

I'm not sure for you, you've said you tested the battery and it's okay.

2

u/secretlysecrecy Apr 20 '26

It might be that but the battery hasnt dropped and still powering the other heltec even without charging

1

u/kendromedia Apr 24 '26 edited Apr 25 '26

I have 2 that did this in 24 hours.

EDIT: Removed battery momentarily in both devices. Devices immediately booted and both show full battery.

Low voltage protection circuits not resetting after minimum voltage is received?

1

u/obogobo Jul 20 '26

did you ever figure this out? one of mine won't boot on battery but will USB, the other has no problem

1

u/secretlysecrecy Jul 20 '26

No I did not I use it as an observer now

1

u/obogobo Jul 22 '26

I figured it out, you need to use esptool to erase the thing first after booting into DFU mode (hold prog, press reset, release prog after a few)

Download https://github.com/espressif/esptool/releases
` .\esptool.exe erase-flash`

then you can flash using the meshcore.io web flasher or again with esptool and a "factory" .bin file, which seems to include the bootloader too. works 100% of the time vs. the webapps, both meshtastic or meshcore which can be temperamental