Our Lithium powered charger uses dual high capacity AA Lithium batteries to recharge our #13 NiMh or #675 NiMh cells. The included Lithium batteries will provide hundreds of hours of recharging abilities while providing complete mobility. There is no longer a need to rely on possible sporadic sunlight or AC current to recharge hearing aid cells. We recommend that you order our battery tester along with your Lithium powered charger. The battery tester tests not only the AA Lithium batteries but your NiMh cells as well.