Different devices may contain different adaptors and in order to offer the most amount of customization, we sell our batteries separately.
If you happen to have a device with removable batteries, you can quickly solve the battery dying issue by picking up a set of batteries with a higher mAh. The mAh, or milliamp-hour, is commonly used to indicate how much power a battery can hold. Thankfully, there are several batteries available with high mAhs, meaning you'll be able to vape for longer.
All that being said, if you have internal cells and you find your device is dying at an alarming rate, your device may have an unfixable error. In this case, it is best to contact the seller or manufacturer to return the item if it is still under warranty.