Hello everyone,

I’m working on designing a production-ready 2G GPS tracker and would really appreciate guidance from experienced members, especially regarding power management and GPS module selection.

Project Overview
I am using:

• ESP32-C3 Mini (main controller)
• SIM800L (GSM/GPRS communication)
• Planning to add a high-sensitivity GPS module

Requirements

1. Fast GPS Fix & High Sensitivity
   • I need a GPS module that can acquire coordinates even with weak signals (urban areas, indoors near windows).
   • Looking for recommendations with fast TTFF (Time To First Fix) and good sensitivity.
2. Wide Input Power Range
   • Input voltage: 9V to 72V DC (vehicle battery compatibility)
   • Need a reliable power management circuit that:
     • Steps down voltage efficiently
     • Handles automotive noise/spikes
3. Backup Battery System
   • When main power is present:
     • Device should operate normally
     • Backup battery should charge automatically
   • When main power is removed:
     • System should seamlessly switch to battery
   • Also want battery tamper detection
4. Ignition Detection
   • Detect vehicle ignition ON/OFF (ACC line)
   • Should be safely interfaced with MCU
5. Remote Engine Cut-Off
   • Ability to control a relay remotely via GSM
   • Needs safe and reliable circuit design

What I Need Help With

• Recommended GPS module (high sensitivity + fast fix)
• Complete or reference power management circuit design:
  • 9V–72V input → regulated outputs (ESP32, SIM800L, GPS)
  • Battery charging + automatic switchover
• Suggested backup battery type (Li-ion, LiPo, etc.) and capacity
• Best practices for:
  • Automotive protection (TVS diodes, filtering, etc.)
  • SIM800L power stability (handling current spikes)
  • Ignition sensing and relay control

Notes
I am relatively new to hardware design, but I want to build this as a robust, production-level device, not just a prototype. Any schematics, reference designs, or guidance would be extremely helpful.

Thanks in advance for your support!

 

You are asking a lot. I could give you all the guidance you need up front, but then I'd be doing my paying clients a disservice. I'm happy to provide input, just like the many 100s of professionals on this site who give 1000's man-hours of support to hobbyists and other professionals but the overriding rule, IMHO, is this: You do the work, the research & the planning, then you put your work up for critique and input. You don't get 1000's of man-hours of experience free of effort by yourself.

So, here's my one free piece of input: When all major UK, EU and world networks have announced closure of their 2G & 3G networks, why are you suggesting using 2G?
https://streetwave.co/mobile-networks/2g-switch-off-by-country-guide/