LiPo battery calculator
The battery (LiPo pack) is one of the biggest expenses in our hobby - at least for the electric guys. Unfortunately the C rating (the indicator of the performance of the battery) printed on the LiPo packs are not very "accurate". Due to the lack of standardisation the manufacturer can print more or less what they want on their batteries.
To be able to compare the performance of different brands of Lipos, Mark, Wayne and John developed the The Lipoly Objective Performance Database. The database builds on the "true C rating" of LiPo packs calculated by the internal resistance and the capacity of one cell of the pack. The mainspring of the database is their great LiPoTool which does the calculation. We added some values to the calculator and put all of it below for your convenience. Please support their awesome work and put your results in their database.
KEEP IN MIND: The calculator is based on empiric values as well as theoretical assumptions. The iR of a battery changes depending on temperature, discharge rate and dynamic and even depends on the method used to measure it. Therefore the results can just be seen as a rule of thumb and are without any guarantee.
Details about the calculator
The calculator utilizes the values of one cell of your LiPo pack. To get the real life C rating of your packs you need two values.
The first one is the capacity in mAh of the cell which is easy because it is simply the capacity of the pack itself (i.e. 5000mAh).
The second one is the internal resistance (abbr. iR) in milli Ω of the cell. You have to measure this value. Unfortunately this is not possible with a standard multimeter but most of the chargers (i.e. iCharger) are able to measure the iR of the pack and the cells. An even more accurate way to measure the internal resistance is to use an ESR meter. Wayne builds a great ESR meter which is perfect for our hobby. You can order it directly from him.
IMPORTANT: To ensure best comparability and accuracy leave the LiPo pack at room temperature for at least one hour before measuring the internal resistance.
About the values of the calculator
You have to enter the capacity of the cell/pack in mAh.
To calculate the true C rating enter the cell's iR in milli Ω and click "Calculate C".
To calculate the cell's internal resistance enter the C rating in "true C rating" and click "Calculate iR".
If you enter the cell count of your setup/pack as well the total voltage drop of the setup/pack is calculated when drawing the continuous current.