Battery autonomous car alarm.

Projects General Guidance
1

Hello,

I need please some guidance about the best way to implement a car alarm with autonomous battery.

I have experience at work with industrial PLC and programming but I'm lost in Arduino world with low budget systems.

Car alarm requirement:

  • Avoid touch/manipulate car electrical circuit if possible
  • Alarm to be installed inside car, passanger/driver area. (easier installation)
  • Secondary power supply, at least when car isn't on. (avoid extra cabling from car battery to inside car and draining car battery)
  • Reliable, avoid false alarm.

Sensors proposed:

  • Magnet switch in two doors
  • Gyroscope/Accelerometer
  • Bluetooth emisor/receptor 4.0
  • Bluetooth BLE beacon (with car key)
  • SIM 900 card, for mobile alarm call/SM
  • Buzzer 120 db, 12 V

Current draft project:

Arduino nano 5V
Power bank 20.000 mAh 5V
12 V power supply only when car is ON, recharge powerbank, know if car is on/of (when ON, 12 v are available on car charger)
DC-DC step up 5 V-12V for buzzer

My main concern is power consumption, due accelerometer sensor monitoring, I assume arduino can't sleep, so even at 1Mhz speed clock, current will be 8 mAh + sensor. I suppose other sensors, I could stop draining consumption with relay until alarm is triggered. Not sure if Arduino Nano input/output are enought for all sensor, never worked with gyroscope (9 pin).

Logic isn't a problem, I can programm anything needed.

Am I in the good way? Is it feasible? Made sense?

Thank in advance for feedback.

3

Delta_G:
You know what they say about assumptions.

You might want to research that a little bit. You have assumed wrongly.

My sentence " due accelerometer sensor monitoring, I assume arduino can't sleep" wasn't clear. I mean, if I need to ready accelerometer value, Arduino can't go to sleep mode. I know arduino has sleep mode, but then it will not possible to read values inputs constantly. Right?

My sentence was missunderstood or I loose some fancy funcionallity in this microcontroller? Thanks.

By the way, I use the forum precisely to avoid read thousands of pages specification and documents of all components I could use...Your answer sound rude and inappriopate to me in a project forum guidance.

5

Thank for your answer. I got your point about time events duration and sleep mode activation/desactivation.

For doors for sure it works, for small hits/vandalism not sure if I will miss it or not depending code implementation. As I told, I'm not familiar with all specification sleep switch time on/ off and at the end I will not be sure 100% alarm functioning. Testing will be random not covering all real cases.

It's a turnaround and adding risk of bad functioning in my opinion, I will prefer to avoid by hardware now that I'm in design phase.

I have seen Arduino pro mini at 3.3V and 125 khz consum only 0.5 mA. But then I will need a DC-DC step down component with eficiency loose, handling 0.5 mA low current and sensors, relay working at 5V compatibility.

I haven't found cheap Arduino pro mini with pin pre-solded, I'm a disaster with welder :roll_eyes: + pro mini interface is more complex to load code, test and check monitoring, I will need a Arduino Nano to do it, adding complexity.

All these combinations is where I need guidance or maybe some completly new better approach.

7

Powerbanks usually only turn on with high current devices, it shuts down if the output current drops below a set threshold.

This may be a stupid suggestion at this forum, but as you said you are not good at soldering yet, have you tough about using an old Android phone for that?