A basic rule of thumb about battery charging: The more
capacity (mAh's) a battery has, the longer it will take to charge.
Think of the battery capacity like the gas
tank of a car. The more mAh a battery has, the longer you can use the battery during use. The larger the gas tank in a car, the farther you can drive it before you need to refuel.
The typical "ciga-like" (cigarette size battery) will only have roughly 250 mAh capacity, and should take less than an hour to charge.
cigalike
Many "mods" may have up to a 3000 mAh capacity battery, so they may take 2 - 3 hours to charge.
mod
Charging times can also vary by the charger's amp charging rate. The cigalike charger may have only a 0.5 amp charging rate, which is slow compared to a 1 or 2 amp rated charger which the mod may use.