When you buy a starter kit it usually includes 2 pieces of ecigarette batteries. You should always have at least 2 ecig batteries so you can go on vaping while the other is being charged.
The ecig batteries are sensitive to hits, liquid, heat and cold. Therefore it would be a good idea to have spare batteries in case something happens to those you have.
Here you can buy extra batteries, either in a diffent size or with a different look.
The stated battery life (before needing to be recharged) is highly approximate, since it obviously depends on how much you vape and what mizer you are using
Be aware that most ecig batteries have a "cut off" - that is, you have to press the button 3-5 time to unlock the battery or to lock it again. It is a convenient feature that allows you to have your battery in your pocket or bag without the danger that it might start discharging.
You must push the button each time you want to vape, hold it while you vape and then release it again.
An ecig batteri has a limited lifespan. It ranges from 3-12 months depending on how much you use it and how well you treat it.
Some good advise about batteries:
Pressing either too hard or at an angle can cause the button fall into its case rendering the battery useless.
Your misers and the charger should only be screwed on until contact is made. Screwing things too far can damage the positive pole.
Only charge until the battery indicates that it is fully charged, and never leave the battery in the charger.
Keep your batteri in a hard case when transporting it.
Clean the positive pole located at the bottom of the connection every day using a cotton swap. Be careful not to press the pole down.
Don't use a defective miser that leaks. One small drop of eliquid on the positive pole after a couple of hours vaping does not matter. Simply wipe i of with a cotton swap. Excessive amounts of eliquid can enter the batteri causing it to short.