What batteries can you charge with the portable charges?
One of the most popular portable charges is Nitecore Intellicharger that allows you to charge up to 8 batteries at the same time. You can charge (18650 - 2500) batteries, however charging your vape batteries with a portable charge it will increase the life and always will charge 100%.
What mAh mean?
The mAh stands for milli Ampere hour. It is the measure of a battery's energy storage capacity. The higher mAh the battery has the more power the battery can store inside.