Trust me and the rest of the guys here when we say buy a couple packs 8 or 12 or a kit from Costco or walmart with a Charger and you'll be surprised at the runtime and long life from the Sanyo Eneloops.
They work and they are worth it. Do a search for battery options or power outage options on here and see what everyone says about them. Li-Ion are powerful but they require constant watching to keep them safe.
external charge your eneloops like we do here and you will enjoy your scanner for years,