Meshtasic is cool. The quickie description from their website is: "An open source, off-grid, decentralized, mesh network built to run on affordable, low-power devices". It's a way to send SMS type messages without the use of the internet, cell phone infrastructure, etc. The hardware is cheap and there are Android and iPhone apps to that support it.
We wanted to experiment with Meshtasic and purchased the RAKwireless WisBlock Base Board from Rokland. One nice thing about the WisBlock Base Board are the many supported 'plug and play' modules that allow for easy expansion.
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Enough about that... the problem we had was running the WisBlock base board with battery power. There is a right way to do this and there is the way we did it. The right way is to use a rechargeable LiPo battery with the connector already installed.
But... this is what we did mainly because we already had a drawer full of USB portable charging battery bricks. Like many other USB powered devices, the current draw from the WisBlock Base Board is so low that when powering it from a USB portable charging battery the portable charger will just shut down thinking there is nothing connected to it. Our fix was to add a 100 ohm load. The WisBlock makes this super easy from the on board BATTERY socket (see "right way" above).
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Here's the current draw (~15mA) without the 100 ohm load added. All of our tested USB portable charging battery bricks would shut down:
We plug in the 100 ohm resistor and now all of our tested USB portable charging battery bricks stay activated with ~53mA current draw:
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Does it use more juice? Of course it does, but even the small lipstick battery shown will last for days and that's good enough for our use.
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FWIW, here is what our Meshtasic portable rig looks like:
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