Metr LTE is here | GPS tracker with SIM card designed for ESK8

Vendor Corner (SERIOUS)
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Great writeup on a functional use case for the Metr LTE

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Hey Roman! How has testing been going with that tiny 5V step down in the photo you shared? :smiley:

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It works. Metr Pro CAN + Metr LTE + GPS and all those are powered with 5V from the regulator and not from CAN.

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Would you be willing to sell that step-down module on your website?

Also, I just had an amazing feature request – if Metr is always on thanks to the stepdown module, you could theoretically send a message when metr detects that the board’s voltage is dangerously low. This could be a life-saver for batteries! :smiley:

Also I'm way more interested in Metr LTE now after I saw a Youtube video of someone trying to track another person down using an Airtag. The airtag... can be practically useless against thieves XD
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That would be amazing, but Metr modules unfortunately have no voltage sensing capabilities. In order for this to work you need to keep VESC on.

I would like to have a better package in order to sell it (plug and play). Right now I have a few 50V → 5V regulators (Pololu D36V6F5) but they require soldering which some may argue is not very user friendly. You can get one for free together with Metr LTE. :wink:

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Hi, I am wondering if there are any significant updates on the horizon for LTE? I ordered one a few days ago and also ordered a voltage converter that says it converts 12-80V to 5V, is the external power currently working for the device or is that still in development? I am very excited to get it installed.

I would really love to be able to give it full throughput for logging rides independently, even if it costs more data. Looking at prepaid data cards through companies like Mint, it looks very reasonable, $10/gigabyte or so.

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Thank you for your order! There are updates in the pipeline for the next year. Looking forward for your feedback and suggestions!

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My LTE unit doesn’t seem to be working right lately… On the account screen, the map never loads. And also, on the settings screen, no info about the SIM card is shown. Both were working normally when I first installed the chip.

Also I was wondering about the live location sharing, it says on this post that it is a launch feature, but I don’t see where I can actually do that…

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Please check again, it should be working now. Live location sharing should be available in the main sidebar → Tracking.

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Is anyone else using LTE with the SD+GPS? I figured out that my LTE was not working because the GPS was plugged into the SD module. When I was trying to diagnose the issue I plugged the GPS into the LTE with a Metr Pro CAN (no SD) and it worked as normal. Wondering if anyone else is having the same issue, it says in this original post that it should work with the GPS on either module.

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I have a Metr Pro CAN SD and LTE module on the way. It looks like powering it while the vesc is off isn’t yet an option but would it hurt to power it off a usb battery now in anticipation of it working at some point in the future?

Would the proper way to wire this be plugging the gps module into the Metr Pro and sending the usb battery power into the open CAN slot on the lte module?

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The Metr has to be powered from a 5V source. The easiest is to find a buck converter that can take your battery pack voltage and step it down to 5V reliably. This will keep the Metr running continuously. Please keep in mind that this will also keep ground connected through the metr to your ESC, (as ground is required for CAN connection) so always be sure (if you disconnect power for the ESC from the battery to charge) that the ground is first to be plugged in, last to be unplugged. Positive should be last to plug in, first to unplug. Otherwise you’re charging your ESC capacitors through the tiny wires for the Metr and they might pop. (Ask me how I know)

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Just so I understand, you mean a portable power bank like for recharging a phone but installed in the enclosure? You’d need some way to recharge this power bank, so in theory it could work but in practice it would probably be just as complicated to try and work out power bank recharging

IMO the way to do it is get a small buck converter module that can run off the board’s main pack voltage. Attach this to BMS output so the Metr can’t drain the main battery below a safe level

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I’ll look into the buck converter. How do I makes sure that ground is always first to go in? Is that a specific plug or do I just modify something?

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Correct- a portable power-bank like for a phone. I was thinking that I’d either add a charging port to the controller box or ideally I was hoping it would be possible to charge the battery from a 5v pin off the vesc. Looks like the buck converter is the way to go.

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This would need to be a high-side BMS, and those are very hard to come by. Almost any off-the-shelf BMS is gonna fry something if it ever cuts the load.

Most BMS don’t cut the red wire, they cut the black wire.

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Finishing testing with power bank only, update coming soon!

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Yeah I only thought of that after posting, good catch. The Metr CAN uses 2-wire comms with no shared ground, it doesn’t mention being opto isolated or anything so it’s safer to assume it isn’t, and also to assume you’re right and it’s unsafe

Disclaimer: speculation below, do not take this as advice

I think the only way a low side switching BMS would mess up a buck and/or Metr would be if there was an unintended path to ground that keeps them half alive when the BMS disconnects, or keeps the buck going long enough to burn out this unexpected ground trace. It would be through the ESC (UART ground, or an unintended ground path through the CANH/CANL) and also would require that none of the units have polarity protection on ground. From what I remember nfets blocking reverse ground are fairly easy polarity protection but I think diodes on the positive rail are more common.

Doesn’t seem like a good idea to find out the hard way though

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Hopefully everything ready now!

Metr App: v4.20.14
Metr Pro FW: v5.57
Metr LTE FW: v5.16

The latest app and firmware should allow for continuous tracking as long as Metr LTE + GPS is powered.

  • Power Metr LTE with external 5V, not CAN bus
  • Connect only CANH and CANL from Metr LTE to CAN bus
  • GPS module must be connected to Metr LTE
  • If you swap GPS module from Metr Pro CAN, please be very careful and check cable / pinout. Only latest revision of Metr Pro CAN + SD come with symmetric GPS cable, same as Metr LTE. Please remove the cable from the GPS module and use the cable that came with Metr LTE!
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The Metr Pro does not also need to be powered by external 5v to work? That’s interesting, I thought it was dependent.

Also can the Metr Pro w/ SD retrieve GPS data from the LTE in this configuration?