# Calculating battery charging time

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The charging time for a battery or battery bank (lead-acid and lithium-ion) can vary depending on several factors such as the charging current, the state of discharge, and the type of charger being used.

As a general rule of thumb, to calculate the approximate charging time for a battery, you can use the formula:

Charging Time = Battery Capacity (in AH) ÷ Charging Current (in A)

Note that chargers charge battery with some additional voltage and current because a battery bank will always require some 2-5% additional voltage and current to charge itself than actual ratings.

Let’s assume you have a 150Ah battery and a charger that provides a charging current of 10A:

Charging time = 150 Ah ÷ 10 A

Charging time = 15 hours

However, this is a simplified calculation and doesn’t account for factors like efficiency losses, the initial state of charge, or the charging method (constant current, constant voltage, etc.).

In practical scenarios, the charging time might be longer due to various inefficiencies in the charging process. Also, different types of batteries might have specific charging requirements, so it’s essential to refer to the manufacturer’s guidelines for the specific battery model you have. If your charger provides a different charging current, simply use the formula above to adjust the calculation accordingly.