Hy muler,
Welcome to ETO.
I see you are from Ethiopia. This gives us an idea about your mains supply voltage and also what components you are likely to be able to buy (placing your area in your tag on the left allows us to immediately see your location, without having to access your profile page).
Charging batteries in series is fought with problems. Although it may not seem so at first consideration, your best bet is to use 6 independent battery chargers and connect one charger across each battery. The batteries could still be connected in series if required. The battery stack, even while on charge, could still be used to power any equipment if that is what you want to do.
You need to choose the battery type appropriate for your intended use. In general, there are two broad categories of lead acid batteries: automobile types and deep discharge types. The deep discharge types are designed for static applications, like boats and campers. Used for the latter, standard automobile batteries would not last long.
If you could tell us a bit more about your application that would help us give you the most comprehensive answer.
spec