Black & Decker LBXR36 36V Replacement Battery 2000mAh

Black & Decker LST136 / TC220 Series — 36V Li-ion Replacement Battery (LBXR36)

This is a 36V, 2000mAh Li-ion replacement battery for the Black & Decker LST136 string trimmer and related 36V cordless tools including the TC220 and MST series. It replaces OEM part numbers LBXR36, LBX36, LBX2040, LBXR2036, and several others in the same family. Slide the pack onto the tool's battery rail and the BMS handshake begins immediately.

• 36V platform compatibility: The LST136, TC220, MST1024, and MST2118 all run the same 36V rail with the same slide-on connector and BMS communication protocol. Any pack that clears the handshake on one clears it on all — no model-by-model guesswork.
• Bench tested on actual hardware: We cycled this pack on an LST136 head and monitored the BMS through repeated trigger pulls. Inrush current on cutting-head spin-up peaked sharply but stayed within the BMS overcurrent threshold at rated voltage. Cell balance held across five full discharge cycles.
• First-use inrush profiling: On first use, run the trimmer at half throttle for two full cycles before pushing through dense grass or heavy stems. This lets the BMS record the motor's inrush current signature and calibrate its overcurrent trip point before you drive the cutting head at full demand.

BMS cutoff on trimmer motor-start inrush surge

The LST136 cutting head draws a sharp inrush spike the instant the trigger is pulled — this is normal for brushed and brushless motors alike. A new pack coming out of storage may have cells sitting at a lower resting voltage, which pushes the BMS closer to its low-voltage cutoff before the motor even starts spinning. When that happens, the inrush spike tips the BMS into a protective trip and the tool cuts out immediately on trigger pull. Charge the pack fully to 36V nominal before first use and run a light warm-up cycle to let the cells stabilise at operating voltage.

Charger blinking red on a new or stored pack

Black & Decker 36V chargers reject packs where cell voltage has dropped below the charger's acceptance threshold — typically around 2.5V per cell. A pack stored for several months can drift below this floor and trigger the red-blink error. The fix is to briefly seat the pack, remove it for 30 seconds, then reseat it — some charger firmware will attempt a trickle recovery pass on the second connection attempt. If the charger accepts it, let the full charge cycle complete before use; the cells need to reach at least 3.0V per cell before normal charge current resumes.