AA SIZE 3.2V LiFePo4 (Lithium Iron Phosphate) specifications Capacity: 650mAh Voltage: 3.2V Discharge Cut-off voltage: 2.0V Charge Current: 0.1 A~ 0.6A (Recommend 0.3A~ 0.5A) Charge Voltage: 3.65V Continuous Discharge Current: 0.1A-0.6A Positive: Button Top Dimensions: Diameter is 0.55 inch (14.1 mm), Length is 1.97 inch (50.1 mm) Customer Instructions 1) Solar batteries have to matched by VOLTS (3.2V LiFePo4)and SIZE ( standard AA size, diameter x length : 14.1mm(0.55 inch) X 50.1mm(1.97 inch) otherwise they will not work2) Don't mix the battery with different capacity or manufacturercommon Question & Answer1. Are these batteries already RE-charged fully? ◆Answer: No, It is 80%- 90% charged, Please install in solar device that be charged fully by the sun.2.how long do the battery keep the solar light on?◆Answer: Normal keep solar lights on 6-10 hours( get a good amount of 6-8 hours sun shine for fully charge), The time will be shorter when the poor sun shine or IN Winter3. Is the LiFePo4 AA same as LiFePo4 14430 battery? ◆Answer: No, the Length of AA is 1/5 inch longer than 14430, the diameter is same.4.Can i use this in solar lights that use a lifepo4 AA 400mAh or 500mAh or 600mAh or 700mAh 3.2v rechargeable battery?◆Answer: Yes, this battery will work great in your device. The battery size (AA, diameter x length : 14.1mm X 50.1mm) & voltage (3.2V) match up