Battery capacity refers to the total amount of electricity a battery can store. It is a basic parameter of batteries. Common units are ampere-hours (Ah) and milliampere-hours (mAh). They can be converted using the formula:
1Ah = 1000mAh
Watt-hours (Wh) and kilowatt-hours (kWh) are also used to describe battery capacity. Their conversion relationship is:
1kWh = 1000Wh
While both can describe capacity, they have differences. Ah and mAh indicate how long a battery can discharge at a specific current. For example, a 10Ah lithium iron phosphate battery can discharge for 5 hours at 2A.
Wh and kWh indicate how long a battery can discharge at a specific power. For example, a 10Wh lithium iron phosphate battery can operate for 2 hours at 5W.
To convert Ah to Wh, you need an intermediate value: voltage. Voltage, or electric potential difference, is measured in volts (V) and represents the work done by the electric field force. It is also a basic battery parameter. You can convert Ah to Wh using the formula:
QWh = QAh × V
For example, if your solar battery is 20Ah with a voltage of 12V, its watt-hours are 240Wh (20Ah × 12V).
The best discharge depth of a solar battery is crucial for calculating its runtime. To know this, you need to identify your battery type, as different types have different optimal discharge depths. For example, lithium iron phosphate batteries have a discharge depth of about 80%, while lead acid batteries are around 50%.
Different brands may also vary due to construction and materials. You can find the best discharge depth in the battery’s user manual, which helps you use it correctly.
The stored energy in a solar battery powers the load when the solar panel is not working. Generally, the higher the load power, the shorter the runtime; the lower the load power, the longer the runtime. Thus, load power directly affects solar battery runtime.
Finding load power is simple. Most solar inverters display load power, allowing you to monitor their operation. You can get the load power from the solar inverter’s display.
Once you know your solar battery’s Ah, voltage, best discharge depth, and load power, you can calculate its runtime. Here, QAh is battery capacity, V is voltage, DoD is discharge depth, P is load power, and t is runtime. The formula is:
t = ( QAh × V × DoD) / P
For example, if you have a 200Ah, 48V lithium iron phosphate battery with an 80% discharge depth and a 700W load, the battery can power the load for 1 hour.
The solar battery runtime calculator is an essential tool. It quickly and accurately calculates how long your solar battery can power your load when the solar panel is not working. This helps you plan electricity usage and choose the right battery.
Using the calculator is easy. Just enter the required data into the correct fields as prompted. Make sure the data and its placement are accurate to get the correct result.
Understanding the formulas for solar battery runtime makes you more familiar with your battery. The runtime calculator also saves you time and effort by avoiding complex calculations. You should use it wisely.
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