I rec’d this handy tip from Jim B:
I was experiencing unreliable DiNotte battery connections like you were. For my trunk light, a rubber-band cut from an innertube and holding down the connector to the battery holder terminals solved the problem.
For the front lights, I found that the 4-cell battery holder fits just right into a Topeak cell-phone case. The stretchy sleeve on the side holds the light’s power cord. I have not experienced a single accidental disconnect since adopting these cases several months ago. The battery removal from the case is easier than with the DiNotte-supplied floppy bag. Also the whole battery and case can be quickly separated from the mounting hardware if need be (like theft prevention).