How to Calculate the Charging Time and Charging Current for Battery Charging?
Easy Battery Charging Time and Battery Charging Current Formula for Batteries. (With Example of 120Ah Battery).
Below is a simple battery charging current and battery charging time formulas with a solved example of 120Ah lead acid battery
Here is the formula of charging time of a lead acid battery.
Charging time of battery = Battery Ah / Charging Current
T = Ah / A
T = Time hrs.
A = Current in Amperes
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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.
Charging current for 120Ah Battery = 120 Ah x (10/100) = 12 Amperes.
But due to some losses, we may take 12-14 Amperes for batteries charging purpose instead of 12 Amp.
Suppose we took 13 Amp for charging purpose,
Charging time for 120Ah battery = 120 / 13 = 9.23 Hrs.
But this was an ideal case…
Practically, it has been noted that 40% of losses occurs 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
Putting the values;
168 / 13 = 12.92 or 13 Hrs ( in real case)
Therefore, an 120Ah battery would take 13 Hrs to fully charge in case of the required 13A charging current.
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