First off, I am a ME student, and I only know enough about electricity to get myself into trouble. I am looking to build a flashlight using a 100w LED chip, a step up constant-current transformer from 12V (or 24V) to 34V and either one or two 12V batteries (higher voltage to improve efficiency). My goal is to make this project portable and easy to recharge without taking the batteries out to charge. It would be ideal to plug the flashlight into the wall after the batteries have worn down and let the batteries charge while not having to monitor the voltage. I'm sure there are many AC to DC rectifiers that sense voltage and shut off at the appropriate voltage. But would there be a safety risk or LED damage if, say, I were to loan this to a friend and they decide to turn on the flashlight while plugged into the wall? Would the AC to DC converter just simply be connected directly to the battery terminals? Are there other safety considerations that I have not thought of?