Well, they *do* have a discharge rate as it's a physical/chemical property that all battery have, but it's indeed never stated (to mu knowledge at least) on NiMh batts...
To OP: you say your mini has the ROF of a 7.2.. That means nothing in itself; as you saw yourself, different batteries of the same voltage will yield different ROF (but will generally will play in the same ballpark)
The reason your mini as a lower ROF than your other 8.4v, is because it has a lower discharge rate; why? Because the cells are smaller, as simple as that.
The more surface area a battery have, the higher the discharge rate.
I don't claim to be specially kbowledgeable in batteries, it's what I learned/understand. I might be wrong on some point, but unless someone proves me wrong I think I do understand all this correctly.
Originally Posted by Brian McIlmoyle
Real life comparison,
GBBR- bang bang -- Giggle
AEG-- merrrzip merrzip -- meh