If there is any grease or crud on the battery, it could cause problems. In most cases, the battery should last the life of the vehicle. My 01 truck has the original battery and so does my 08 Taurus. I use them a lot. Sometimes they do not like to work, but it could interference or a gremlin. Like everything automotive, there are always components that do not meet standards. When you think about how many batteries are made, even .001% slipping through means a lot of key fobs.