Meshtastic

My giant battery node I've place on a hill in Los Angeles

This is a 560 watt hour 36v scooter battery and a heltec board I’ve packaged up in a trash bag. Zip tied it to a tree, you can find it on the meshtastic map in Los Angeles. So far I’ve gotten a signal to bounce back to my house from 10+ miles away.

Anyone in LA want to give it a try? Its been running for about a week non stop so far.

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Super Cool! Btw to prevent the node from sleeping (ever) for this application you’ll want to use the new --set-router mode we just added. Also it will use much less current. Docs are still a bit spotty on it (and no gui yet on the Android app) but see the alphatest thread for details.

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Expected runtime before recharging? Or, will the tree die first? :grinning:

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awesome! looks like i’ll be taking a trip up the hill!

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hahaha, I really have no idea! I’ll be checking its voltage when i go up there to update the software. It would be great if it could do a couple months!

The feature will be available in the Android app really soon :blush:

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I’m in Lincoln Heights but I’ll try to hit tonight!

awesome!, the base station should be named “homebase” and ill be either datadrian or adrian tbeam. send me a shout so i can look out for a message

Nice node! What software were you using for the RF prediction?

Hey, looks like the second one from this post:

I saw your node from Angel’s Point in Elysian Park. I tried sending a message but I don’t think it went through. Will try to hit it again soon.

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That’s awesome!!! I’m currently traveling for work until thanksgiving, but that is sooo.awesome! That’s like7 miles?

Ok I retrieved the node today for charging as I wasn’t able to ping it anymore. Looks like we got just about 2 full months out of 42v 560 watt hour battery. Kinda feeling like it should have gone longer. I’m updating to 1.1.8 and setting router mode. I’ll put it back in the tree next weekend and see what’s she does from there.

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Do you have the data sheet for the buck converter? It may not be as efficient as it could be.

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I bet that’s absolutely the issue. So I still have the lora device connected to it’s own 18650, wonder if I could trigger a relay every 3 days or so to turn on the buck converter for 4 hours to charge the battery.

I mean I bet that would work right?

Didn’t really see any consumption data on the amazon page

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Do you have access to a bench power supply and a multimeter with a DC current measure feature (most multimeters can do this)?

If so, set your bench power supply to the nominal voltage of your battery.

Connect the step down supply to that.

Then connect your multimeter set to measure current in series between the geri module and your lora module.

On the bench power supply, multiply the voltage * amps to get the wattage drawn from the bench.

On the multimeter set to measure amps, multiply that by 5 to get the watts drawn by the lora device.

Subtracting the two watts will give you the inefficiency of the step down module.

Here’s something that jumped out at me:

That’s based on the LM2596 switcher by Texas Instruments.

The data sheet ( https://www.ti.com/lit/ds/symlink/lm2596.pdf?ts=1606577586355&ref_url=https%3A%2F%2Fwww.google.com%2F ) says it’ll take a max of 45V.

Page 8 of the data sheet shows the efficiency graph of 5v and 3.3v outputs. Looks like a worse case of about ~80%. That’s pretty good.

I looked at your picture a little closer. The way that’s wired, you’re regulating down the big battery down to 5v and then there’s a regulator from that on your lora board to bring it down to 3.3.

You’ll get more efficiency if regulate your battery down to 3.3v and go straight into the 3.3v pins of your lora board.

At least after that, the next place to gain power savings is to use the router mode on the module.

You may also be losing power from the self discharge of your lithium pack. That’d be something you can also test with a multimeter.

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yes i agree with all that, I have a bench supply that can measure everything down, but the point is moot as this is the hardware I have at the moment, and honestly 2 months isn’t that bad. When I’m back from work travel next week I’ll perform the tests and reinstall it in the tree with the router mode set and see what happens.

Really I should be hiking up to this park more than once every two months.

can a 42v - 3.3v regulator even be found?

also, thanks for taking the time to consider my problems. its pretty cool of ya

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