How is the nominal voltage of a battery determined?
A NiMH cell's usable voltage ranges between around 1.4-1.0V and the nominal voltage is quite in the middle of that at 1.2V.
Similarly, the nominal voltage of a LiPo is given most of the time between 3.7V and 3.9V, with the usable voltage being between 3.0V-3.5V and 4.2V-4.6V. So again, the nominal voltage looks to be in the middle of the usable voltage.
But for Alkaline cells the nominal voltage of 1.5V is at the very top end of the usable voltage of 1.6V to 1V.
So how is the nominal voltage determined, and is there a difference between primary and rechargable cells?
To clarify the question because there are a few answers that apparently misunderstood the question.
On some chemistries the nominal voltage is close to the maximum voltage of the cell (e.g Alkaline with 1.5V, where a fully-charged cell has 1.6V), while others have their nominal voltage at the average charge (e.g. NiMH at 1.2V or LiPo at ~3.8V).
Why are some nominal voltages close to fully-charged voltage, while others have are at 50% charge? Is the difference that primary cells have their nominal voltage at 100% and rechargable cells have it at 50%?
I am NOT looking for answers to those questions:
- How can I find out the nominal voltage of a battery?
- Why have different chemistries different voltages?
- What are primary/rechargable cells?