How long your SERIES-B DNA 75W mod kit will last from one charge will depend on a number of factors, such as wattage settings, usage and the mAh of your IMR battery.
For example, if you are running a sub-ohm coil at high wattages and are a heavy user, you will find that one charge will last just a few hours. However, if you are using a high resistance coil at low wattages and are a light user, you will get at least a day, maybe even two days from one charge.
The IMR 18650 battery itself is expected to last around 4 months, and is guaranteed for this time. With good care and maintenance, the SERIES-B DNA 75w device will last a long while, but is guaranteed for 6 months. If either item fails within this time, please contact our Customer Services team.