Node only works on USB not on battery

[lorimo]

My node shows a curious behavior. It's based on a pro mini 3.3V, a DHT22 and a NRF24L01.
When switching on the battery, the node goes into a boot loop showing up the red LED repeatedly.

If connected via an FTDI Board to USB it boots up, connects to the gateway and shows up in my domoticz. Then the Sensor data come in correctly as from the other nodes.

So I think this could not come from the code, it must be something with the wiring. In both cases i find the correct 3.3V on all places. There are no shortcuts i could find. From the FTDI board I need to connect GND, CTS, VCC and DTR for the node to work.

The battery pack (2x 1.2V 750mAh ) is connected to GND and VCC over a Step-up power converter.

Any suggestions where to search for the reason?
Thanks

[mfalkvidd]

@lorimo connect the node to ftdi and the battery at the same time, but don’t connect Vcc on the ftdi. That will let you see the debug log (with MY_DEBUG defined), which will probably help figure out what is happening.

[gohan]

Did you put a capacitor on the booster output? Led flashing fast constantly it could also be a bootloader problem so you could try any other open bootloader (I have been told that minicore works well)

[lorimo]

@mfalkvidd the main error seems to be (with description from log parser)

51 TSF:MSG:SEND,3-3-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
Sent Message
Sender: 3
Last Node: 3
Next Node: 255
Destination: 255
Sensor Id: 255
Command: INTERNAL
Message Type:I_FIND_PARENT_REQUEST
Payload Type: P_STRING
Payload Length: 0
Signing: 0
Failed uplink counter: 0
Status: OK (OK=success, NACK=no radio ACK received)
Payload:
6152 !TSM:FPAR:NO REPLY
No potential parents replied to find parent request
6154 TSM:FPAR
Transition to Find Parent state

But this does not help me, because still it works fine if powered direct from FTDI.

[lorimo]

@gohan the LED does not flash fast. It goes on for a couple of seconds and is off for about half a minute.
I didn't add a capacitor, is that really necessary? What capacity do you recommend?

[mfalkvidd]

@lorimo See https://www.mysensors.org/build/connect_radio for more information about the need for stable power.

[lorimo]

@mfalkvidd OK I'll try that. But as expected, there is no suitable capacitor left over in my box.