+2 Don’t make the rather common mistake of thinking nimh charge Voltage is the same as discharge Voltage. Due to internal resistance they will be considerably different. As they age and the charge Voltage goes up the discharge Voltage goes down even.

Back to the life, aren’t they 10.8 Volts fully charged for a 3s, and come close to holding that for a while? Much higher than 7 nimh under load , seems kinda risky for a 7 cell nimh rated controller. But if it’s rated for 3s lipo no problem.