SMAKN&reg; Lithium Battery Charging Module 4.5-12V Wide Voltage 2A LTC4002 Charge Board Volume is only 29mm * 18mm * 5mm (L * W * H). Input voltage: 4.5V-12V (recommendations input 5-8V). Output voltage: 4.2V  0.03V. Output Current Default: Default 2A. Charging efficiency: 92.8%@5V input 4V2A output, 88% @ 9V input 4V2A output, 86.7% @ 12V input 4V2A output.