Hi Bob,
I tried the cordless drill adaptor on a 6" auger a couple seasons ago. Worked great while the ice was up to about 15" or 16" thick. The ice eventually got over 20" that year and at that point two holes per battery was about it, became almost useless.
That being said, another guy had a 5" on a high-end drill and could drill the 20" in seconds, all day long it seemed.
I think the key is a better drill and smaller auger. The wobble can lay a beating on the bearings of the drill as well, the average handy-man drill can't take the abuse for long.