B4 I got the Passthru version, I gave mine a swipe with a tissue every time I put it on the charger. These type of batteries explode and have major flames when they do. The ones these have happened to was during charging.
That's why I got the passthrus. Many of the ego chargers are junk, it adds an additional point for venting, the micro-usb cable is common to other devices, and I can leave my carto tank attached for the few weeks til it needs changing.