Bosch GBM 12VES-2 Replacement Battery 12V 3300mAh

Bosch GBM 12VES-2 Series 12V Ni-MH Replacement Battery (BPT1004)

This 12V, 3300mAh Ni-MH battery replaces the original pack on Bosch GBM 12VES-2 and GSB 12VSP series cordless drills. It fits the same terminal block and slide-in connector as the OEM unit. Matches part numbers BPT1004, BH1204, and 2 607 335 158 among others.

• GBM 12VES-2 and GSB 12VSP-2/3 platform fit: These models share the same 12V slide-pack housing, terminal layout, and BMS communication protocol one battery services the full lineup without adapter or modification.
• Bench tested on actual hardware: We ran this pack through trigger-pull cycles on a GBM 12VES-2 and monitored the BMS response to motor inrush current. The overcurrent threshold held at the correct trip point and the pack resumed normal discharge after each spike without latching fault.
• Ni-MH break-in on first use: Run the drill at half load for two full cycles before driving at full torque. This lets the BMS log the motor’s inrush draw and calibrate its overcurrent thresholds before you hit peak load conditions.

BMS cutoff on motor-start inrush in the GBM 12VES-2

When you pull the trigger on a cordless drill, current spikes sharply before the motor reaches running speed. On a new or cold Ni-MH pack, this inrush can briefly exceed the BMS overcurrent threshold and trip a protective cutoff. The GBM 12VES-2 housing adds thermal mass around the pack, slowing the cells’ warm-up and raising internal resistance early in a session. Starting with lighter loads in the first two cycles trains the BMS and reduces false trips under full torque demand.

Drill bogs down mid-hole without cutting out

If the drill slows noticeably under load but does not shut off, the most likely cause is voltage sag from elevated contact resistance at the terminal rails not cell failure. Debris and oxidation on the slide-pack contacts create resistance that drops the voltage rail under load. Clean both the battery terminals and the tool’s contact plates with a pencil eraser or fine abrasive, then re-seat the pack firmly. If sag persists after cleaning, check resting cell voltage a healthy 3300mAh Ni-MH pack should read between 13.2V and 14.4V fully charged.