1.326650 li-ion batteries 2.CE,ROHS,UL Approval 3. ... Item: Cheapest 3.7v 4000mAh 26650 li-ion batteries use for external battery pack ModelLi-ion batteryStandard Voltage3.7VMax ... and negative (-) terminals. Otherwise, during recharging, the battery pack will be reverse-charged, abnormal chemical reactions then ... specification. Cheapest 3.7v 4000mAh 26650 li-ion batteries use for external battery pack