UPDATED AGAIN Sorry folks. I kind of jumped the gun with this question. I was patient and let the charger do its thing. The voltage increase flattened out as the rate of temp change increased. The temp never made 50°C, it topped off at just under 45°C then shut down. Seems like I have a functioning charger setup after all.
UPDATED Deleted unnecessary question.
Three AA size LSD NiMH batteries in series are connected to Maxim Integrated's DS2715 Charge Controller Evaluation Kit. NiMH batteries are all 1.2V nominal, and as I understand 1.0V minimum 1.4V maximum. With a maximum of 1.4V the three cells should be fully charged at 4.2V.
The charge controller uses cell temperature (from a thermistor) to determine charge status. At 50°C the controller should stop charging. My problem is that the battery pack is fully charged at over 4.2V, yet the temperature of the cells is only 32°C. How far can I let this go? At the rate of change in temp I'm seeing, the rig will blow up in my face before the cells reach 50°C.