I never leave chargers on anything sitting.I saw a pretty good fire started by a Deltrans float charger.It failed,didn't float,overcharged and the tractor went up in smoke.Things are fine as long as they work as they are supposed to,but when they fail you never know until something happens.I will use a trickle/float combo charger overnight to bring up a low battery,but won't use it constantly.I don't know what's going on where folks need to have a charger on all the time.I parked my roadster in a shed last November,last week I went over,put the fuse back in it,started it up and have been driving it since.That car has a battery dated 2003,and I run a generator with an EVR.I also run halogen bulbs. My 30 pickup runs the same combination,shut off in the fall and started a few weeks ago.No charging.I did have to charge up my 54 Studebaker,but only because I ran it down churning it over to pump fuel up to the carb after sitting all winter.6 volt generator system on that too.