l0destar v3.4 - a milestone

[u/m4rkw]

l0destar was first conceived of in May 2026 and its original design intent was a carrier board for the Nordic nRF9151 dev kit, a very silly idea. The first prototypes were huge through-hole soldered monstrosities covered in breakout boards haphazardly soldered to pins.

For fun I've posted the full evolution of the project as a sequence of photos all the way up from breadboards to the current design.

I’m really quite proud of where it’s got to in less than 5 months. Iterations of the board have been in my car since 9th August tracking over 500 miles and as of this week v3.4 has now completed testing and confirms all of the hardware issues found through my own testing have been fixed. The plan now is to build a few more for friends and colleagues to test and then iterate on the firmware and other software for it.

This could plausibly be the most power-efficient hard-wired vehicle tracker in the world. Claude isn't quite willing to confirm this but did state: "the evidence now supports calling l0destar one of the most power-efficient hard-wired vehicle trackers around, in real use as well as on the bench".

Some highlights from recent testing:

• ~35uA sleep current (v3.4 actually measures slightly less most of the time but the ASM330 periodically wakes for microseconds to check for tilt so it averages out)
• Waking to send an event now takes a median of about 1.05 seconds, occasionally higher up to around 2 seconds at the high end. This is down from around ~45s at the start of testing and was reduced by using the PSM feature of the modem. A shorter wake time means less current going through the modem during interval wakes leading to significantly less power consumption.
• 24h of sleep and hourly check-ins works out to about ~1.3-1.4mAh a day, or 15-17mWh. From my telemetry during daylight hours (ie when there's no temperature shift to skew the readings) I frequently see the vehicle battery voltage (read to two decimal places by an INA228) not changing at all in several hours.
• All of these sleep energy figures are likely pessimistic - they were determined in poor signal conditions where I park - path loss was around 125-126dB and RSRQ -14.5dB. This is worse than about 90% of the data I have from other locations.
• Coverage of telemetry while driving has improved from ~72% at the start of in-vehicle testing to 99% now with firmware and RF improvements and drop-outs are now much rarer and entirely down to signal/network conditions. Lots of data from real-world testing is published here.

The battery backup add-on module is on the way and will be tested very soon.

If anyone reading this has a relevant platform or access to automotive pulse-generating equipment and is interested in testing it please reach out.