Hi,
im using the wisen talk2 whisper with a TinyLora Application.
It works fine, powered via USB or 2 AAA batteries.
Yet, if I want to power it via VIN Pin and a 3.7V LI-ION battery pack, I see a strange behaviour.
4 out of 5 times the application seems to crash during the setup. 1 out of 5 times it starts normally
The behaviour is like the power would no be sufficient, but the LI-ION battery is fully loaded and has an actual voltage of 4V.
Any idea, whats wrong here?
Best regards
Jakob

Hi Jakob,

Does this behaviour happen when running another program? For example:

• if you run the standard Factory Firmware, what voltages does it shows in the terminal?
• do you have any sensor connected to your project?

Here the output from a testing Whisper Node running the factory firmware with a 18650 Lithium Battery: Please note I connected only the RX and GND pins of my FTDI adapter to make sure the WP Nodes is not being powered by the FTDI adapter.

One important aspect to note is that VIN supports from 3.4V to 6V. If the voltage drops below 3.4V the power supply will "fall-back" to the VBAT. Maybe take a reading of the battery voltage at the Whisper Node terminal, if you have an oscilloscope even better so we can see if there's any voltage drop when your project runs.

What could be happening is if you have a sensor (or other device connected) or if some behaviour is happening that demands more current that your battery is being able to supply this will cause a voltage drop below 3.4V and the WP Node might restart.

The Problem seems to be in the Lora Setup and gets more rarely, if I reduce the Lora txpower (from 17 to 5).
I don't really understand this, because the battery should have more than enough power: Max current 4.9A.
I try your suggestion later.

Hey Jakob,

That's some interesting information. When transmitting at high power, the radio requires some high-current to work. If you are using a long lead/cable or if the power supply or battery is not fast enough to delivery such "current pulse" the voltage will drop and can cause the whole system to restart.

Try adding a large capacitor (at least 10uF-22uF) as close as possible to the Whisper Node where you're connecting the Lithium Battery Pack. This will act as an energy buffer. Again, if you have access to an oscilloscope would be ideal so you can visualise it.

Regards,

Can you recommend a Good moderate priced osci for Arduino purposes?

It would depend on the kind of project you'll be working on. As a starting point, the DS1000Z is a very good value https://int.rigol.com/products/oscillos ... 1000z.html and you should be able to upgrade most of it via software if necessary.