YILI YLD01-20V2AH 18V Cordless Drill Replacement Battery 4000mAh

YILI YLQ2010D-B — 18V Li-ion Replacement Battery (YLD01-20V2AH / YLD01-20V4AH)

This is an 18V Li-ion replacement battery for the YILI YLQ2010D-B cordless drill. It carries a 4000mAh / 72Wh capacity and fits the original battery slot using the same connector and BMS communication protocol as the factory pack. Two OEM part numbers cover this fit: YLD01-20V2AH and YLD01-20V4AH.

• YLQ2010D-B platform fit: The YLQ2010D-B uses an 18V slide-pack form factor with a specific contact rail pitch and BMS handshake. This replacement matches that rail layout and communicates over the same data line the charger uses to confirm pack state before releasing charge current.
• Bench tested on actual hardware: We ran this pack through motor-start inrush cycles on a cordless drill platform. The BMS held through repeated trigger-pull spikes without tripping overcurrent protection, and cell voltage recovery after load stayed within the expected window for a fresh 18650-based Li-ion pack.
• Break-in load protocol: On first use, run the drill at half load for two cycles before full-torque applications. This lets the BMS profile the motor inrush draw and calibrate its overcurrent threshold before you push the tool to maximum torque.

BMS cutoff on the YLQ2010D-B during motor-start inrush surge

Cordless drills pull a spike of current the moment the trigger closes — often two to three times the steady running draw. On a new pack, the BMS overcurrent threshold may be set conservatively from the factory until it has seen a few real-world load cycles. If the pack cuts out immediately on trigger pull, this is almost always the BMS responding to that inrush spike rather than a cell fault. Run the drill unloaded for two to three short bursts first, then move to light-load work before attempting full torque or heavy fastening.

Charger blinking red on the YLD01-20V2AH pack after storage

If the pack has sat unused for several months, individual cells may have self-discharged below the charger's acceptance threshold — typically around 2.5V per cell. Most chargers will refuse to push full charge current into a pack reading below that floor and signal the fault with a red blink. Some chargers include a recovery or trickle mode; select it and let the pack sit for 10 to 15 minutes. Once cells recover above 2.8V per cell, the charger should switch to its normal charge cycle automatically.