# Checking the Battery Voltage
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The DeltaQuad Evo Battery has a nominal voltage of 22.2 V (3.7 V per cell). When fully charged, it reaches 25.2 V (4.2 V per cell). The battery and individual cell voltages can be measured with a battery checker, as explained below.
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* The DeltaQuad Evo Battery has a power lead with an XT90 connector. This cable and plug are used to power the DeltaQuad Evo.
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The power lead is not used for checking the battery voltage.
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* The smaller cable, called the balance lead, is a multi-pin connector that allows the checker to measure the voltage of each cell.
* Connect this multi-pin connector to the battery checker.
* On the balance lead, the outer wires serve as the pack’s main negative (black wire) and positive (red wire) terminals.
* Connect the balance lead as indicated on the battery checker. The checker will be powered by the battery through the balance lead.
* To get an accurate battery percentage readout, set the battery checker to Li-ion type. Use the middle button to enter the menu, then the arrows to navigate to **Battery Type** and select **LiIon**.
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Once set, the battery checker displays total voltage, cell voltage difference, battery type, remaining capacity (%), and the voltage of each cell.
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**Always** fly with fully charged batteries **(at least 95%)**.
**Voltage Matching (Dual Battery Operation)**
* When operating the UAV with two batteries, verify that the **voltage difference between the two batteries does not exceed 0.1 V**.
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