The question is: "How long does it take to charge my battery bank?"

Here is the formula of Charging Time of a Lead acid battery. Charging Time of battery = Battery Ah / Charging Current  T = Ah / A

Example 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.
Therefore charging current for 120Ah Battery = 120 x (10/100) = 12 Amperes but due to losses,
we can take 12-14 Amperes for charging purpose.
If we use 13 Amp for charging purpose, then charging time for 120Ah battery = 120 / 13 = 9.23 Hrs. for an ideal case.
Practically, the loss is about 40% ( in case of battery charging)
then 120 x (40 / 100) = 48. (120Ah x 40% of losses)
Therefore with 120 + 48 = 168 Ah ( 120 Ah + Losses) the Charging Time of battery = Ah/Charging Current = 168 / 13 = 12.92 or 13 Hrs.
Therefore, an 120Ah battery would take 13 Hrs for completely charging ( with 13A charging current).

Battery charge time


Enter the Amps per hour (Ah) of your battery:

Enter the charging current rate (%):

Solar Panel Amps (0 if you are not sure):