Maybe a silly question, but I just charged some new NiMH 8.4v 5000 mah batteries using a new EZ-Peak plus. I set the current at 5A and Automatic for the charge amperage. For the majority of the charging period they were only mildly warm, but during the last 5-15 minutes they got super warm...difficult to hold. I don't have a temperature probe, so I don't know the actual temp.

Am I doing something wrong or is this normal? I also charged some used 8.4v 3000 mah using 3A and the same thing happened.