I've posted this a couple of times in this situation. I really think that c-caution is not the best search term, though. Maybe someone could suggest a better one. This may be a langauge issue.
How about using a road flare? I wouldn't trust an electroic device in a pinch after having sat in my car for months or years without being used. Some of these school projects really make me scared if any of these people are going to become engineers. Sometimes you really have to ask yourself "Why am I building this this way?"