Bosch PSR 18 LI-2 Replacement Battery 18V 4000mAh

Bosch PSR 18 LI-2 Series — 18V Li-ion Replacement Battery (2 607 335 040)

This is an 18V, 4000mAh Li-ion replacement battery for the Bosch PSR 18 LI-2 cordless drill driver and compatible 18V platform tools. It fits the PSB 18 LI-2, PSB 18 LI-2H, PSM 18 LI, and over 37 additional Bosch 18V models sharing the same slide-rail battery interface. OEM part numbers covered include 2 607 335 040, 2 607 336 039, and 1 600 Z00 000.

• PSR/PSB 18V platform compatibility: These models share a common 18V slide-rail connector, battery management handshake protocol, and cell format. The BMS communication lines are identical across the platform, so one battery pack covers drills, sanders, and multi-tools in the same voltage family without modification.
• Bench tested on actual hardware: We ran this pack on a PSR 18 LI-2 under repeated trigger pulls and sustained load cycles. The BMS held cutoff thresholds correctly at motor-start inrush and did not trip spuriously under mid-range torque applications. Cell voltage balance remained within 20mV across the pack after five full charge-discharge cycles.
• Motor inrush break-in on first use: Run the drill at half load — no more than half trigger depression — for the first two charge cycles. This lets the BMS sample actual inrush current from your specific motor before it locks overcurrent trip thresholds, reducing false cutoffs during later high-torque fastening work.

BMS cutoff on motor-start inrush surge in the PSR 18 LI-2

When you pull the trigger hard from a stopped position, the brushed motor in the PSR 18 LI-2 draws a short current spike — often two to three times the steady running current. A new or freshly stored battery pack has not yet profiled that spike, so the BMS may interpret it as a fault and cut output immediately. The fix is not a faulty pack — it is an uncalibrated overcurrent threshold. Running two break-in cycles at partial trigger lets the BMS establish a baseline before you apply full torque. After those cycles, hard trigger pulls at full load should no longer cause an instant cutout.

Charger shows blinking red and never accepts the pack after storage

Bosch 18V chargers reject packs where individual cell voltage has dropped below roughly 2.5V per cell — the charger reads this as a fault rather than a dischargeable state. This happens when a pack sits unused for several months and self-discharges past the charger's acceptance threshold. To recover, apply a brief trickle from a compatible Li-ion charger set to a recovery or wake-up mode until pack voltage climbs above 2.8V per cell, then transfer to the standard Bosch charger. If the pack does not respond to trickle within 15 minutes, cell reversal may have occurred and the pack should be replaced rather than forced.