Engineering projects solution for students

Q:Easy Charging Time Formula for Batteries. ( with Example of 120Ah Battery)

Ans: 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 120 Ah battery,
First of all, we will calculate charging current for 120 Ah battery. As we know that charging current should be 10% of the Ah rating of battery.
so charging current for120Ah Battery = 120 x (10/100) = 12 Amperes.
but due to losses, we can take 12-14Amperes for charging purpose.
suppose we took 13 Amp for charging purpose,
then charging time for 120Ah battery = 120 / 13 = 9.23 Hrs.
but this was an ideal case...
practically, this is noted that 40% of losses ( in case of battery charging)
then 120 x (40 / 100) = 48 .....(120Ah x 40% of losses)
therefore, 120 + 48 = 168 Ah ( 120 Ah + Losses)
Now Charging Time of battery = Ah/Charging Current
168 / 13 = 12.92 or 13 Hrs ( in real case)

Therefore, an 120Ah battery would take 13 Hrs for completely charging ( with 13A charging current).