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need to design a low-cost SMS-based alarm with a very long life battery. Answered

extremely low-cost SMS-based alarm, that will send a message to a number when the alarm is activated. must be small (10x50x40 cm) and have a long life battery and is to be deployed over a wide geographical area, all within GSM reception



there is such a unit for boats. pretty much it is a low power security system and depending on the trigger, both a sms text and a ring/call is made to the numbers you specify. it also has its own sim-card, so it is effectively a mobile phone for a dedicated purpose.

The local fire station put in fire alarms in every room in my house and changed the standard battery to a 9v battery that is supposed to last for ten years, even with weekly testing, so the battery technology is there.

Genuinely, if it was me, I'd be thinking of two batteries, one as main and one as stand-by, with both being hot-replaceable.

@ steveastrouk i can spend anything but, i am supposed to desin it at extremely low cost...

thanks kevinhannan for the idea...

Define "long life" ? How often may it trigger ? I can contemplate a system that is essentially off until it receives a trigger, starts up, and transmits a message.


let's say a month at least, like you are saying, the system can be almost off until it is triggered

I'd buy a GSM modem to do this. What's your budget ?