Black & Decker LBXR2036 40V Replacement Battery 2000mAh

Black & Decker LST136B / LCC340C Series — 40V Li-ion Replacement Battery (LBXR2036)

This is a 40V Li-ion replacement battery rated at 2000mAh (80Wh), built to the same voltage and connector spec as the original LBXR2036 pack. It fits the LST136B cordless string trimmer and a wide range of Black & Decker 40V platform tools including the LCC340C and LHT2436. Drop it onto the existing charger and it reads the pack the same way the OEM unit does.

• 40V platform fit — LST136B, LCC340C, LHT2436 and more: These tools share a common 40V battery rail, slide-lock connector, and BMS handshake protocol. One pack works across the group without adapter or modification.
• Bench tested on actual hardware: We cycled this pack on an LST136B under full-load cutting passes. The BMS held the voltage rail steady through motor-start inrush and showed clean cutoff at the low-voltage threshold — no mid-cycle drops outside normal sag.
• First-cycle load management on the trimmer: Run the trimmer at partial throttle for two full discharge cycles before pushing it through dense growth or thick-stem weeds. This lets the BMS log the motor's inrush current draw and set its overcurrent trip threshold correctly for your unit.

BMS cutoff on LST136B motor-start inrush surge

When the LST136B cutting head spins up from rest, it pulls a brief current spike — often three to five times the steady-state draw. A new pack fresh from storage may have a BMS that hasn't profiled your tool's inrush yet, and it can trip the overcurrent protection as a precaution. This shows as an immediate shutoff the instant you press the trigger. Two or three short trigger pulls of one to two seconds each let the BMS log the spike pattern and stop treating it as a fault condition.

Charger blinks red and won't accept a new pack after storage

Black & Decker 40V chargers have an acceptance voltage floor — typically around 20–25V. If the pack sat discharged for weeks, individual cells may have self-discharged below that threshold and the charger refuses to start a charge cycle. The fix is a short trickle-boost: some chargers have a recovery mode triggered by holding the pack in the dock for 30–60 seconds before the charge LED activates. If the charger still won't engage, check cell voltage at the pack terminals — any reading below 20V across the full pack means the cells need a recovery charge at 0.1C before normal charging resumes.