PD100W do it yourself fast charging battery charger for 4 pieces 21700 polymer 20000mA power bank box for MacBook needs welding

URL link for welding and assembly video (1): https://video.aliexpress-media.com/seller/play/5000196630297.mp4 URL link for welding and assembly video (2): https://video.aliexpress-media.com/seller/play/5000196634143.mp4 It is only a power bank case, batteries need to be welded and are not included. The battery must be connected in the circuit to the motherboard. Connect the positive terminal of the battery to the "B+" terminal located at the back of the motherboard, and the negative terminal of the battery to the "B-" terminal at the back of the motherboard. After welding, it is necessary to connect the power source to charge the power bank and activate the power bank. Then it can be used normally. Features: A back case for power that you can make yourself, capable of charging 4 pieces of 21700 batteries (batteries need to be welded and are not included). Supports bidirectional fast charging protocol PD with 100W power. 100W output supports PD, QC, AFC, SCP — multi-protocol fast charging for laptops, phones, iPads. Can be taken on a plane without declaration, safe and reliable. Transparent body, imported high-quality LED screen that can check remaining power in real time. Specifications: Item: 4-piece 21700 battery charger box Capacity: 20000mAh Material: ABS-PVC Color: Black Size: approximately 153 × 55 × 34 mm Input: DC 5V/3A, 9V/3A, 12V/1.5A, 10V/2.25A Output: Type C 1: 5V/3A, 9V/3A, 15V/3A, 20V/5A Type C 2: 5V/3A, 9V/3A, 15V/3A, 20V/3A USB: 5V/3A, 9V/2A, 12V/1.5A, 10V/2.25A Quantity: one set of DIY kits (batteries and charging cable not included) Note: 1. Conversion: 1 centimeter = 10 millimeters = 0.39 inches 2. Please allow a measurement error of 0-1 centimeter due to manual measurement. Make sure you don’t mind before placing a bid. 3. Due to differences between screens, the actual color of the item may not reflect in the picture. Thank you! Package includes: 1 set of DIY power kits Q&A: 1. Q: Does this product include the necessary welding accessories? A: The package only includes some accessories such as the motherboard and case as shown in the main picture, and does not include wires and other accessories required for welding. 2. Q: What if there is no response when pressing the button after welding the battery to the motherboard? A: In some cases, the motherboard needs to be activated after welding is complete. Charge it with a charger for 3-5 seconds to activate. 3. Q: The power bank’s energy display quickly drops to 1% but it can still be used. What is the reason? A: This happens due to incomplete matching between the motherboard and the battery. You can fully charge the power bank, then drain the internal battery. Repeat this process 3-5 times, and the power display of the power bank will return to normal.