The Duracell Ion Speed 4000 NiMH Battery Charger offers amazingly fast charge times of 1-2.5 hours* with 4000 mW** of charging power. It recharges any rechargeable AA and AAA NiMH battery from any brand. You can recharge 2 or 4 batteries at a time and, with the LED Charge Status Indicator, you'll know when charging is complete. It also features an Auto Shutoff so you won't use any unnecessary electricity. It even has a bad-battery indicator along with 9 smart safety features. Plus, the Duracell Rechargeable Pre-Charged NiMH batteries are guaranteed to last 10 years.****To approx. 85% of full charge when using 1300mAh up to 2500mAh 2xAA NiMH Batteries (included). **Based on charging AA batteries.***Or 400 recharges, whichever comes first.