I didn't thoroughly read through all the posts, so forgive me if you got your question answered. I ran NiMH batteries in a light maybe twenty years ago. The light detected a drop in voltage and would shut itself off. The first fall, this started happening about 13 miles into a 23 mile commute on cooler mornings, like around freezing. The batteries would cool down and the voltage dropped, and the light thought they were out of juice. Fortunately, the light didn't like the cold either and died that winter. I moved onto lithium ion after that.