I looked at some clip-on-the-frame battery LED lights at WCAF. The effect was of dim, yellowish incandescent bulbs that had been in service way too long. Very poor color quality that completely lost blue skies and other cool colors. I was told the choice for the designers of those products is that there are high CRI LED's with pretty good color quality, but that use a lot of current, or relatively low CRI LED's with pretty poor color that require much less current for the same amount of intensity. So the tendency is for AC powered LED lights to be of the better quality, and battery powered lights to be of the lower quality. But CRI's under about 85 look like crud, and I think most battery operated LED lights fall in that category. But OTOH LED lighting systems are evolving rapidly are they may be exceptions.
If you're thinking about art fair booths, I have a set of 6 of these bulbs
that will run off a cheap AC inverter and deep cycle marine battery for about 2 long days between charges, using my normal AC wiring and sockets. Or if AC is available, no battery needed and the low wattage will help me stay under the bar for shows that have a power limitation. The light quality is really very good, although somehow there is a little less snap and sparkle in the prints than I see with halogen bulbs. Was a little pricey to do this for just one particular show each year, but I probably recouped cost the first time I used the setup because the space was pretty dim.