Originally Posted by rkswyo
I currently don't have one on my trailer. My last trailer had one and I never used it. Dumb question: Why should I have one and when would I use it?
rkswyo - Ditto on what Herk said. It serves the same function as actually removing a battery from a vehicle to prevent it from becoming discharged - but instead of actually disconnecting the neg and pos cables and removing it, you simply throw a switch to accomplish the sane thing.
Most common use I have for it is to keep the battery from becoming discharged from lack of use when shore power is not being used.