I agree that powering up a locomotive and leaving it on the track for long periods unattended is risky at best. For this reason I have invested in separate battery chargers (including the MTH chargers for engines with charging ports) for the 3V and 9V batteries used in MTH engines. I have also used BCR's but have not found them to be trouble free. The disassembly required to remove a battery is not difficult. I have charged batteries on my workbench and just change them out so there is no waiting to run an engine if it has been sitting for more than a couple of weeks.