Originally Posted by
djmcnz
Joules First Law
Heat (Q) = Current squared (I^2) x Resistance (R) x Time (T)
[...]
When we talk about heat, we keep current constant. Always.
Myth Busted!
Yep, that's exactly where you're wrong.
Q=Uexp2*t/R
which is where indeed you can replace Uexp2/R=Iexp2*R to give the equation you wrote above, but this is what is misleading you (and others) into reverse engineering the equation and deciding that heat depends directly proportional to resistance, when in fact is inversely proportional.
That implies assuming that you can choose your current which you can not, as I said before. All you can do is choose your voltage and your load (resistance). Current is a derived measure from these two.
When we talk about R/C all you have is a battery with a fixed voltage so we keep voltage constant. (not sure I understand why you postulated keeping the current constant anyway as even that doesn't help your case at all).