The real question is, are you talking about "exterior" or "interior" detailing?
If "exterior", forget the headlamp, you need lots of soft light to see any haze in the paint while polishing. A hand held light can help find flaws when you think you've got it all, while doing a final inspection.
If "interior" is the focus, then sure, a flood style headlamp would be the way to go. I would stick with an AA size light and rechargeable NiMH batteries, which should give you several hours of light per battery, and when you swap out a cell, you can just bung the spent cell into a decent, yet inexpensive charger, and not have to worry about the shop burning down because you forget to unplug it on Friday afternoon.
CRI or Color Rendering Index is how accurate you can see any given color in the light from the flashlight you are using. If you are just looking for dust and dirt, this may not matter to you that much. If you are looking for something like a coca cola stain on a dark brown cloth interior, a higher CRI led might be worthwhile. I just made up the coke on brown thing.... it could be coffee, maybe lipstick on a red seat cover... I dunno.... things that are close in shade might not show up with a low CRI light. Zebralight have cool white and neutral white, with the latter being a bit higher in CRI I believe. I don't know what level of detailing you are doing... if you're working on multi million $ cars... a few hundred dollars on a headlamp is a mere pittance. If you're working at a drive through car wash where you just expected to catch the occasional half eaten donut under a car seat.... Any cheap light will probably do.
I'd look at something from Zebralight to start.... As for chargers, I'm not really up on the "good cheap stuff" as I've been out of the loop for a while. Others will chime in, I'm sure.
Regards
Christian