What is the purpose of the tune parameter on the DC voltage terminal?
The Tune option in the battery properties is basically used to control how finely you can adjust the voltage value of the battery. Normally, when you move the voltage slider or type a value, the change happens in bigger jumps, for example from 3.9 volts to 4.0 volts. This can sometimes be a problem when you want to set the battery voltage to a more accurate or precise value, such as 3.93 volts or 3.931 volts. The Tune feature solves this issue by allowing you to make the voltage adjustments in much smaller decimal steps.
When you increase Tune, the battery properties increase after the decimal point. This means the voltage value can be set in finer increments, and the number of digits after the decimal point can become more detailed. For example, instead of adjusting only in tenths (0.1), you can adjust in hundredths (0.01) or even thousandths (0.001).
In simple words, Tune acts like a fine adjustment control knob that gives you precision. If you are doing experiments where you need exact voltages, for example 3.93V instead of just 4V, then you use Tune to make sure you can set the voltage as precisely as you want. If you do not care about small differences, you can leave Tune as it is, and the battery voltage will change in bigger, quicker steps.
So, Tune does not change the actual power of the battery itself, it only changes how smoothly or precisely you can set the voltage value in the battery properties.