Building or repairing a battery pack for a power tool, DIY project, or anything using three 18650 (or similar 3.7V) lithium-ion cells in series? You NEED a Battery Management System (BMS) like this Rakstore board. This is a 3S (3-cell series) BMS that outputs 12.6V. It provides crucial protection against over-charging, over-discharging, short circuits, and more. It handles a continuous discharge current of up to 20A (so it's good for things like drill motors, but make sure you have proper high-discharge 'power' cells, not regular ones!), and a charging current up to 10A. The board itself is small at 59x20x3.4mm. IMPORTANT NOTES from the seller: You MUST use high-discharge (15C-20C) batteries for tools like drills. Wire it exactly per the diagram (0V, 4.2V, 8.4V, 12.6V taps). For brushed motors, you need to add a capacitor across the motor terminals to protect the board. And always balance your cells' voltages before connecting them in series. A must-have safety component for any serious lithium battery project.
