I tend to change the battery vs on board charging, it always seems when I go to leave the house the darned thing is near empty. I got out of the habit of onboard charging when I moved away from Ego batteriesI have the same Samsung in mine that it shipped with. It was lasting a long time until I started driving it at 30-40w. Battery life is just ok at high wattage compared to other mods at similar wattage.
Time for a change maybe? I haven't killed a battery yet, so how long do you keep yours in circulation?