text: I'm calling BS on this post... 
  If you buy your smoke/CO2 detectors from a dollar store, ya you could have some problems with them, but  then again you get what you pay for. If however you buy a name brand like Kidde from a reputable store like Home Depot or Lowes they'll work......Guaranteed. 
  Kidde is the largest smoke/CO2 detector manufacture on earth, they test their products over and over before packaging them, there's no way they're going to be associated with a defective smoke detector as long as you do your part and keep the batteries fresh. Can you imagine the lawsuits and recalls they'd face?, their products are everywhere, hotels, office buildings, hospitals and schools.