One of the biggest expenses with maintaining smoke alarms is the cost of batteries. Since you don't want to let the batteries go for too long, you need to constantly cycle them out about every six months. Not only is this expensive, but it's a time hassle too depending on how many alarms you have. If you're looking to save some time and money, you may want to consider using photoelectric smoke alarms in your home instead of traditional battery powered ones. These photoelectric smoke alarms run off of a small photovoltaic cell that comes with them, meaning you never need to use batteries.