Is there a free app to test the health/capacity of a non oem battery?

I've downloaded a few iPhone battery apps to test an aftermarket battery. The apps appear to show none other than what I already know; the current percentage of battery power left, the voltage, run-time, etc. But none show information that's similar to what the built in iPhone health feature shows, such as the health of the battery and it's current capacity. I'm guessing these apps can't read additional data from an aftermarket battery, because two apps show a capacity of 100% which I know is false and say the health is perfect. I'm also assuming some of these apps just steal the data from the battery health option that's already in the iPhone, because one asked for access to the battery health option, which gives the impression these apps don't work on aftermarket batteries, and simply relay minimal information.