Frustrated with UV lights, need help

Try the Jaxman 365nm UV Flashlight, it use an AA-battery.

http://www.aliexpress.com/item/Free-Shipping-JAXMAN-365nm-UV-Flashlight-Torch-for-Fluorescent-Security-Detection-Stamp-Banknotes-Identify/32327280432.html

The best AA-rechargable are Panasonic eneloop. For flashlights, best batteries are rechargable 18650 Li-Ion cells.
With an good battery charger, you can use booth.

What exactly do you mean with “adjustable flashlight” ?
There are flashlights with adjustable beam (zoom head).