Bad mesh performance when powered with USB Power Bank

I’ve been trying to develop a mesh in my local town, including one node on a predominant hill called Denne Hill6e1c. None of the other nodes can reach each other directly without this ‘repeater’. It’s in a rural location and is powered using a 3000mAh 18650 on the back of the tbeam and a “300000mAh” X-Dragon power bank similar, but not identical to, this ebay listing:

The two are crudely cellotaped together and a short usb power cable, in a waterproof bag, hung in a tree. (looking nothing else but suspect!)

Now… a connection is made between St Leonards and Denne Hill fine, they have good LOS and can repeatedly update their location / time last heard. However Alec, as well as another node in Broadbridge heath called D3, are unable to make a connection… Untill … The power bank depletes its battery and Denne Hill starts working only from the 18650 on its back. Then a full mesh is established and all nodes can message each other consistently and successfully.

Could the circuitry in the power bank be affecting Denne Hill in some way? preventing it from relaying messages until it completely powers down due to running out of power? Is that mass of battery right next to the antenna attenuating some signals?

Next Steps:

  1. To run the node with -set-router on and only 18650 battery to test run time and mesh performance.
  2. To run the node with -set-router on and the battery bank attached but physically separated from the tbeam by a 50cm or 1m usb cable

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Most USB power banks use switching regulators which may create RF noise that would affect other devices. You could try moving the USB battery bank further away from the device or trying another USB battery bank.


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Yeah, as I was expecting. I watched a tear down video of an Anker power bank and there were some hefty inductors and capacitors in there, guessing they are used to buck / boost depending on whether charging or discharging. I’ll try and get the battery bank as far away as practical (or maybe try some shielding - Tin foil??)

I’ve got ‘Denne Hill’ running off one 18650 at the moment. The mesh never seems to pass a message on far enough.

I have a node directly under ‘St Leonards’ (‘St leonards’ being in the attic space) called ‘Adam’. ‘Adam’ has suboptimal antenna and can’t hear anyone directly. I was expecting ‘St Leonards’ to “repeat” forward any messages received and ‘Adam’ would receive them.

This doesn’t seem to be happening. Are there any fault finding examples I can follow - debug data I can interrogate - settings I can tweak to ensure the nodes are trying to pass forward?

I notice hop_limit is not a userpreference and cannot be changed using the python api. However, with a default of 7 or even 3 (Documentation is unclear) ‘St Leonards’ should surely repeat forward as it’d be hop 1.

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Hello there, sorry for asking. I am new to this tbeam board. Is it ok to connect our tbeam board with power bank? coz I’m afraid it will damage the board.

If you mean plug the USB into the USB port on the power bank, you might find that the power bank shuts down because the tbeam doesnt draw enough power to keep the power bank turned on, but it wont hurt anything. The USB will only draw x number of milliamps from the powerbank.

If you mean solder the power bank to the battery +/- well that would depend on the total output voltage that the powerbank is configured for.

How about the board powered by power bank only without the 18650 battery at the back? Is it safe for the board?

This is save either, but it might turn off after some time (minutes). (see @satkiwii)

I have a pretty old powerbank, and i did not recognize that it turned off once :slight_smile:

@satkiwii @drewsed thank guys for the advice.:grinning_face_with_smiling_eyes: