I've noticed I'm not getting low battery warnings anymore.   I used to get them with 30% left.    Any idea why?   

Hello there BarnSwallow. I am sorry for the trouble this has caused and thank you for reaching out. May we please know if your DJI FPV is on it's latest firmware and may we also please know what is the model of the mobile device that you are using please? Thank you.

DJI Stephen Posted at 4-29 00:45
Hello there BarnSwallow. I am sorry for the trouble this has caused and thank you for reaching out. May we please know if your DJI FPV is on it's latest firmware and may we also please know what is the model of the mobile device that you are using please? Thank you.

Seems the problem was with the drone, not the batteries.