Battery Charging Current and Battery Charging Time formula

Here is the formula of Charging Time of a Lead acid battery.
Charging Time of battery = Battery Ah / Charging Current
 T = Ah / A
 
Example,
Suppose for 100 Ah battery, 
First of all, we will calculate charging current for 100 Ah battery. As we know that charging current should be 10% of the Ah rating of battery.
so charging current for100Ah Battery = 100 x (10/100) = 10 Amperes.
but due to losses, we can take 10-12Amperes for charging purpose.
suppose we took 11 Amp for charging purpose,
then charging time for 100Ah battery = 100 / 11 = 9.09 Hrs.
but this was an ideal case…
practically, there will be some  40% of losses ( in case of battery charging)
then 100 x (40 / 100) = 40 …..(100Ah x 40% of losses)
therefore,  100 + 40 = 140 Ah ( 100 Ah + Losses)
Now Charging Time of battery = Ah/Charging Current
140 / 11 = 12.72 or 13 Hrs ( in real case)

Therefore, an 100Ah battery required 13 Hrs for completely charging with charging current 11 ampere