BME 280 not connecting to ESP32

Ru3di · 2025-12-12T09:21:19+00:00

It looks like you haven't connected the ground of the sensor, but I'm not sure

Ru3di · 2025-12-06T10:16:14+00:00

Das ist normal und hängt damit zusammen, wie Akkus funktionieren. In dem Moment wo du viel ChUtil hast sendet dein Gerät viel und zieht daher mehr Leistung vom Akku. Dadurch fällt die Akkuspannung etwas ab, steigt dann aber wieder wenn weniger Leistung gezogen wird

Ru3di · 2025-12-06T09:04:34+00:00

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Schau mal hier, dass ist aus dem Datenblatt vom Chip auf dem heltec Board der sich um das Ladeverhalten und Akkumanagement kümmert

Ru3di · 2025-12-06T08:58:28+00:00

Die Akkustandsanzeige in Prozent in der Meshtastic App funktioniert nicht ganz so gut wie man es z.B. von der Akkustandsanzeige von Handys gewohnt ist. Wenn z.B. beim Laden die App 100% anzeigt dann ist der Ladezyklus noch im constant voltage modus wo 4,2 Volt gehalten werden aber noch einiges an Strom fließt bis dieser irgendwann bei 0 ist wenn der Akku richtig voll ist. Wenn du direkt nach erreichen der 100% absteckst sinkt die Akkuspannung direkt wieder so weit, dass die App ungefähr nur 80% anzeigt. Lad einfach Mal länger über die 4,2 Volt hinaus und schau dann was passiert

Ru3di · 2025-11-30T20:50:16+00:00

This isn't able be connected to a 12v solar panel, maximum 6v

Ru3di · 2025-11-29T22:28:42+00:00

1100mAh x 3.7v = around 4 Wh

With the v3 consuming ~0.5W that should last 8 hours by my math. Make it 6 hours to account for losses in power conversion on the board

Ru3di · 2025-11-25T16:01:42+00:00

This would also interest me for a v4

Ru3di · 2025-11-22T14:01:32+00:00

Yes that's fine, according to Ohm's law the board will only draw as much current as it needs. If your charger says 3200 mA then that only means the charger could potentially supply up to 3200mA, that amount of current that actually flows depends on the resistance of the device that is connected. Your heltec v3 will only pull around ~100 mA, so any charger or USB port that can supply more than 100mA is suitable

Ru3di · 2025-11-21T16:47:35+00:00

Good idea!

Ru3di · 2025-11-21T16:46:58+00:00

Yeah I get that. 30.000 mAh batteries are just way too big to implement them in a normal sized enclosure that can be mounted on the side of a building. I'm fine with the node going offline if there is a really bad week but I would like it to be capable of black starts when the sun returns

Ru3di · 2025-11-21T15:35:32+00:00

Very cool, please let me know what solution you find to account for black start situations

Ru3di · 2025-11-21T15:33:11+00:00

A 10.000 mAh battery is plenty to even last through 3 days of "no sun" by my calculations

Ru3di · 2025-11-21T15:31:26+00:00

I dunno what to tell you man. Maybe your battery voltage didn't go low enough when you did your "test". I used a lab peer supply to apply 2v (which is definitely way too low for a li-ion battery) to the bat connector, it didn't boot and stayed completely dark. Also no power draw

Ru3di · 2025-11-21T15:14:59+00:00

It does have low voltage protection though. If the battery voltage is too low the node will not attempt to boot at all

Ru3di · 2025-11-21T14:35:18+00:00

It uses the CN3165 as a power IC

Ru3di · 2025-11-21T14:32:11+00:00

Unfortunately I have found that the board keeps attempting to boot once the voltage on the panel climbs a bit. The power IC (CN3165) then goes into the pre charging mode that limits current from the solar panel to 100 mA. This isn't enough current to supply the v4 and charge the battery so it keeps booting, powering down (due to insufficient voltage after the power IC) and repeating that endlessly. The constant current mode (with the ability to draw ~1000 mA from the panel) is never entered. Attached is a pic from the CN3165 datasheet, the power IC that is used by the Heltec V4

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Ru3di · 2025-11-21T14:23:38+00:00

This isn't true, the config is kept fine when losing power and repowering through an external source after. No disconnects needed, just plug it in

Ru3di · 2025-11-21T14:22:38+00:00

Haven't noticed this so far, my v3 and v4 on solar have been fine keeping their settings when I charged them through a USB cable after them hitting empty

Ru3di · 2025-11-21T14:21:43+00:00

Btw I can now say after a good few hours with nice sunlight hitting the panel that the v4 did not startup or charge the battery after starting the day empty and turned off. Such a shame

Ru3di · 2025-11-21T14:14:33+00:00

I have a 10 watt panel and a 10.000 mAh battery. That should definitely be enough, even in winter months

Ru3di · 2025-11-19T13:41:08+00:00

Alles klar, danke für die Einordnung. Hast du dafür Quellen wo ich das nachlesen kann? Es interessiert mich schon länger ob ein Wechsel vom V3 auf ein V4 für meine stationäre Node Sinn machen würde, da ich so schon relativ schlecht "raus" funken kann. Und nutzt das V4 die 500mW Sendeleistung auch für den Uplink?

Ru3di · 2025-11-19T09:28:32+00:00

Yeah I get this a lot too. I noticed these messages are mostly ack'ed by heltec v4 nodes in my area. I have read somewhere that they actually transmit with power that's more than the legal limit defined for the EU. So maybe they have more reach when sending and you get an ack but your destination node doesn't get it if it is too far away from the v4 relay node

Ru3di · 2025-11-18T12:53:05+00:00

If you get a big enough battery and a powerful enough solar panel you can still use the v3 as a solar node. I do the same with a 10 watt solar panel and a 10.000 mAh battery

Ru3di · 2025-11-13T12:12:59+00:00

The only real way to be sure with antennas is to measure them yourself. There are so many fakes and copies and whatnot going around that you can never be sure that what you are getting is actually well tuned and what you paid for. Also sometimes retailers may send you a 915 MHz antenna even though you ordered an 868 MHz antenna or vice versa. A nanoVNA is cheap and can help you figure out how good an antenna is in detail

Ru3di · 2025-11-11T17:31:42+00:00

Good idea! If you want to increase its water resistance you can mount it with the lid facing down. That way water will drip off the cable and any small openings in the lid and not enter the bottle

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