I have a friend who is getting into quadcopters and being the good techie buddy, I'm trying to find the right technology for battery monitoring so his expensive machine does not fall out of the sky unexpectedly.
So far the only technology for hobbyists that I am seeing is voltage monitors, which aren't really useful for this battery chemistry. With the flat voltage curve LiIon has I'd expect a voltage monitor to falsely report a low battery when you draw extra current and indeed I'm seeing exactly this when my buddy does fast maneuvers mid flight.
In my day job we use charge counting battery monitors (BMS) for this battery chemistry. Usually custom designed for the battery pack (just like for laptop batteries, etc). Sometimes built into the battery pack, or sold by cell suppliers.
Have I missed a product for electric aircraft? Are hobbyists in the battery dark ages?