I’ve got an electric one that goes off in the house. Small PIR unit that you stick in the shed, and (mains powered) receiver unit in the house.
No idea how long the PIR battery lasts for yet – they claim a year, even if it’s only 6 months really, that isn’t too bad, I only put it in yesterday (after my bike* was nicked from there, hmph).
It makes a blooming loud noise in the house so I certainly will hear it if I’m in. I can’t get into the shed at all without setting it off either, I tried quite hard yesterday. Range seems quite good – works even through our big thick old house walls, plus all of an extension, and 50 foot of garden.
It is this one
http://www.ebay.co.uk/itm/DRIVEWAY-ALERT-WEATHERPROOF-ALARM-PROTECT-GARAGE-SHED-/250721699095?pt=LH_DefaultDomain_3&hash=item3a602d8517#ht_4120wt_952
I think the same as this one
http://www.ebay.co.uk/itm/A9-WIRELESS-WEATHERPROOF-GARDEN-DRIVEWAY-GARAGE-OUTBUILDING-BURGLAR-ALERT-ALARM-/250993477419?pt=UK_Burglar_Alarms&var=&hash=item80142625a2#ht_3448wt_952
I’ve also stuck an alarmed padlock on my bikes, which is jolly loud and goes off if you move it at all, as I thought it’d be good to let any thieves know that there was an alarm as well as letting me know that they were there.
Joe
*fortunately only the cheap halfords one rather than the commuter