I have a cable hooked permanently to the battery terminals and ran out the back of the bike to a trickle charge plugin- so when I'm done for the weekend I can just plug it right into the wall. Is this a pretty common thing? Is it safe to do this? I ask because I recently found my battery emptied of fluid and a nice puddle of acid on the shop floor. I think it was an old battery, but I don't want to break another one.