Hi @atnogueira87 ,
Although storage is based on the capacity being about half full, it does somewhat reflect to voltage levels, but of course not in a linear fashion.
From the stored batteries I’ve put a voltmeter on, I have seen it is common for the storage voltage in LiPo cells to be slightly above the rated nominal voltage of each cell, additive such like 0.1v to 0.15v per cell. So based on that, a properly stored 3.7v LiPo cell may read 3.8v.
If you have a 7.4v (2 cell) then it would read approximately 7.6v ~ 7.7v when stored. However I cannot guarantee for certain, as you would have to check with the manufacturer of the product and their recommendations on your specific battery.
The main point of proper storage voltage is to verify the voltage does not fall below the minimum required voltage, and not be excessively charged for long periods of time as excessive charge when idle causes the internal cell resistance to dissipate unnecessary energy which can deplete the overall life of the battery long term since there will be a higher rate of internal chemical reactions. It is also good to cycle the battery every so often when stored for long periods of time, and then put back to storage voltage.
Although it is best for the battery to be sitting at a properly stored voltage, I would easily choose a battery which was stored with a slightly higher recommended storage voltage than a battery that has a risk of going below the minimum voltage as this will destroy the cell(s), cause injury, or fire, instead of typically only reducing the overall lifespan.
Going below minimum or above maximum rated cell voltage will destroy the cell, so in some cases if someone is ever worried about the cell going below the minimum in storage, they sometimes charge slightly above the storage level, which is more common for applications such as high temperature environments, or if they don’t plan regular checks or maintenance as much as they should which of course is not recommended.
Again, this is all generic information. You would have to consult with the manufacturer of the product and their recommendations on your specific battery.