# Measuring approximate battery State Of Charge of a 6S to 12S Lipo or Li ion?

Hello,

How can I measure the approx battery SOT of a lets say 6S lipo battery assuming the system knows what pack it uses and with a resolution of at least 6 steps (0%, 20%, 40%, 60%, 80%, 100%) I know the voltage per cell is 4.2V at 100% SOT and 2.9-3V at 0% (That may not be the case with Li-ion battery as far as I know)

You can measure the voltage with an Arduino. Use a voltage divider to bring the max voltage below 5v.

Whether the measured voltage is very informative is a different matter. The Battery University may have some useful stuff.

...R

Hello,
I want to build a device that can tell in 6 levels the state of charge of a for example 6S battery with just measuring it's voltage any ideas or guidens on how I do that?

I am not sure if this is exactly how its done but i think you can measure the voltage and use a equation that involves the fully charged voltage and fully discharged voltage. I don’t think the relation is linear though, beyond that it would just involve using sensors(you can use 2 resistors for this) to check the voltage of each cell in the lipo off the little white connector. Not sure what the application is but if the cell charges are significantly different, not sure whats defined as significant, then its not a good sign for the battery.