Stickable car alarm

I own a Spark core and was thinking about a cool idea lately when the Electron was introduced. Current car alarm systems (I own an Audi in Europe) fail miserable because they don’t warn the owner personally when something happens. You need to be nearby to hear your alarm sound and when that happens you are always too late.

I think there would be a great market for an Electron based silent car alarm system that can be sticked onto any surface or location in the car. The electron is small enough to make it work. As far as I can see it would need:

  • power from cigarette lighter power socket;
  • backup power from coin cell if intruder removes main power socket. Removing main power would also enable car alarm;
  • PIR sensor (if you use it in the car);
  • movement sensor;
  • app. for settings.

Ultimately it would be even better if it could support some extra sensor modules. The basic stickable module would need PIR and movenement however.

I know in the US there is stuff like onstar but over here in Europe this is non existing for older cars.

Could this work?

Great idea but I think you will get a lot of false positives from the PIR sensor.

Sure, so the question is how to handle it or which sensors are better to use?

turn the entire car into a capacitive sensor?

Cool idea, but I would definitely not use PIR sensors. Those things are way too sensitive, and will give you false positives all the time. The same is true for capacitive sense, so that option is out as well. What you need to figure out it a way to detect whether or not there was an intrusion. Something that normally doesn’t happen when the owner uses the car, unlike a PIR sensor, which just doesn’t care. Perhaps you could use NFC tags in the keys with some sort of scanner. Blue-tooth might work; unless you’ve got a valid blue-tooth connection with a verified device, ring the alarm.
As far as power goes, I wouldn’t use the cigarette plug, but rather hook it up to the car battery. That way, it’s out of sight, and allow you to still use the plug for other purposes. A coin-cell might also be a bit too optimistic as a backup battery. The wireless module requires quite a bit of power, and I’m not sure a coin-cell can deliver that. A battery pack which can recharge using the car battery would be great.
While you’re at it, why not add a GPS module as well? That’d allow you to actually track the car, and even allows you to set up a geofence, if you’d like. SOOOO many posibilities :wink:

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Mmm, I don’t want it to be complicated. It needs to be stickabel and visible. Removing or moving it would trigger the alarm so that is covered. The coin cell is the backup bettery for just sending an alarm message. Removing the main power would actually trigger the alarm and is part of how the system works.

It should be a very simple unit that can be sticked into a car in a very simple matter and fine if it is visible. It should also provide visual indicators to warn possible car hijjackers to leave it alone. Maybe a neopixel ring that turns red if the car senses a possible steal.

There are different ways to do it, just need to see which sensors would work best. I actually think an accelometer is probably good enough.


just had a thought… cigarette lighter power socket only has power then the key is in the ignition position
so you would need some wiring regardless… unless u stuck it in a fuse socket -which I would not recomend

There’s a subtle difference between “not complicated” and “completely useless”, thread carefully.

I’d highly suggest thinking about functionality first, and aesthetics later. It’s great that you want it to alert you when it moves, but how on earth is that a good alarm system? You do realize it would probably start ringing if the car was parked and there is a bit of heavy wind? Not to mention the fact that it would alert you every time the rightful owners uses the car, since an accelerometer hasn’t got the brains to figure out who’s driving. The amount of false-positives you’d get are rediculous.

Then there’s the whole power issue; plugging it into the cigarette lighter would waste that port for useful purposes. If someone was like:“I need to charge my phone/navigation, let’s switch it out”, the alarm would trip (again, those darned false-positives). When/if you unplug it, it’ll need power to send it’s alert message, for which a coin cell probably won’t suffice, considering that a cellular chip needs quite a bit of power. Not even if you use it “just as backup”. It’s like trying to jumpstart your car using four triple-A batteries, admirable, but not really functional.
And like @smogs mentioned, it’d only have power when the keys are in.

So, about the ‘stickable’ thing… Why would you want it to be stickable? I get that your like to retrofit it into existing cars, but are you planning on moving the device very often, or is it a one-time stick?

Functionality issues: imagine you ‘stuck’ your alarm on the inside somewhere, a thief broke in and is highly unimpressed. He sees the thing and unplugs it, then he drives off with your car.
Problem 1: the alarm should’ve gone off before he unplugged it, otherwise it wouldn’t do anything if he didn’t unplug it, which is rather useless.
Problem 2: he drove of with your car. Let’s imagine you were out of hearing range and didn’t hear the ‘normal’ sound alarm. So, now you’ve got a mobile notification that your car has been stolen. Then what? It’s not going to help you get it back. If just let’s you know what you would’ve figured out had you gone to the parking lot later.

Are you aware that neopixels can use up to 60mA each? Your battery won’t like that.
“If the car senses a possible steal”, how on earth does it do that? As human beings we’re quite adept to figuring things out, but even I have a difficult time figuring out what other humans are up to. I’d be amazed if you could point me to a sensor that could identify potential thieves, as I’m sure the cops would as well.

Accelerometers are good for one thing: detecting acceleration. Unless proper additional logic is applied, an accelerometer won’t detect the difference between you driving your own car, or someone else stealing it. That kinda defeats the purpose, doesn’t it?

So the things you need to figure out before planning on where to place it:
-How can I accurately detect possibly theft, without alerting me when the car is in normal use?
-What do I want to achieve by having this system? Notifications only, or something actually useful like being able to track it when nessecary?
-How do I power it, properly?

nothing better than a good old fashioned engine immobiliser…

simple switch on the fuel pump does wonders as long as you splice it in somewhere less obvious