18V/21V Type-C Interface Power Tool Battery Box (with Bms Protection Board) 21V Box-Type Wireless Grinder Cutting Equipment 18650 Battery Holder and Lithium-Ion Battery

Advantages: comes with complete protection (overcharge, over-discharge, over-current, short circuit), no need to rely on tools or chargers, with active equalization (extend battery life, slow capacity decay) diy-friendly, connecting adapters, inverters, and other equipment are all safe. cheap price and easy to maintainMore suitable for third-party tools than the original, such as outdoor lights, electric fans, inverters, car starting power supplies, etc. it will not over-discharge.  Important notes: 1. (diy): this product is a component without battery cells and is intended for repairing and assembling battery packs. it is only suitable for individuals who are familiar with battery performance and have prior experience in battery pack assembly.2.  this product does not provide after-sales service,it is just a set of components without batteries. you need to assemble a battery pack with your own 10 18650 power lithium batteries. we cannot guarantee that you can successfully assemble the battery pack. please purchase with caution! if you have any objection, please do not place an order.AssemblePreparation before:(1). if using a new core, please note: 18650 power lithium battery core must be selected.(2). if the old batteries are repaired, please test the voltage at both ends of each battery. if the voltage is different, charge each battery to the same voltage value.Make sure the voltage of each battery is the same before welding pcb.     3.The type-c of the product can only be charged slowly and cannot be discharged.