Hello, let’s ask you a question: What are the differences between battery trainers and which would you recommend? I have a maintenance-free battery and through the encapsulation (the maintenance-free) I always have the fear that when charging it comes to explosion due to cracking gas formation… I know someone expert who this has happened, and he was allowed to be a guest at the accident clinic for 1 week… So watch out and always clamp the battery with + and – on, and then first the power plug into the Power outlet, but I’m talking about a battery trainer… dsu