What brand of batteries do you use? (Just saw that it's the PowerGenix) NiZn is not new and I have seen batteries years back which offered pretty bad recharge cycles when compared to NiCd or NiMh. Further most of these electronic equipments are sensitive to over / under voltage whereas the under voltage disasters are limited to shutting off the circuits due to voltage below lower thresholds..
Whereas the NiZn offers a open circuit voltage of 1.6v which may be ok if you're using 2 cells in serial (3.2V which is well tolerable for circuits requiring 3V). Imagine the same for 5 cells (5 x 1.6V = 8V) where the circuit is designed to take only 7.5V. The heat that you've mentioned is due to the over voltage offered by NiZn and I wouldn't use them in a long run for equipments which are sensitive to heat..
Last edited by geekbrains; 30th January 2010 at 05:31 PM.
Just to add more to what I've said earlier, some NiZn are not even 1.6v they are 1.65 which makes it much worse or advantage depending on the equipment where it's used. Further, I could find no manufacturer claiming a guaranteed cycle time (They typically claim only 100 - 500 cycles) which is way lesser than what today's NiMh is offering..