hi Arcangel742, i recently got a 510 passthrough setup which, as others mentioned, is nice to have. my first ecig kit came with 2 batteries but you could only charge one at a time and not overnight because you couldn't charge more than 2 to 3 hrs at a time! so the passthrough really comes in handy to use at homewhile my other batteries are charging. i wonder why many chargers don't have timers if overcharging is bad for the batteries?