Steinel MobileHEAT 3 18V Replacement Battery 2000mAh Li-ion

Steinel MobileHEAT 3 / GluePRO 18V — 18V Li-ion Replacement Battery

This 18V, 2000mAh (36Wh) Li-ion battery fits the Steinel MobileHEAT 3, MH3, MH5, and GluePRO 18V cordless heat tools. It slots into the same battery bay and connects to the same BMS handshake these tools use to regulate heating element power. The pack uses standard 18V Li-ion cell chemistry at the same form factor as the original.

• MobileHEAT 3, MH5, and GluePRO 18V compatibility: These Steinel tools share the same 18V battery platform, connector pinout, and BMS communication protocol. One pack works across the range because the voltage rail and cell configuration are identical.
• Bench tested on actual hardware: We ran this pack through full charge and discharge cycles on the MobileHEAT 3 platform. The BMS correctly negotiated cell balancing, the overcurrent threshold held during heating element startup inrush, and the low-voltage cutoff triggered cleanly at the expected rail voltage.
• Heat tool cycling care: After inserting this pack, run the tool at low heat output for the first two cycles before sustained full-power use. This allows the BMS to profile the heating element's startup current draw and set accurate overcurrent thresholds before you push the tool hard.

BMS cutoff during heating element startup surge on the MobileHEAT 3

The MobileHEAT 3 heating element draws a sharp inrush current at power-on — significantly higher than the steady-state draw during normal operation. A freshly installed pack with an uncalibrated BMS can interpret this spike as an overcurrent fault and cut power immediately. This looks like the tool powering off the instant you press the trigger. Running two low-power warm-up cycles lets the BMS log the inrush profile and stop tripping on it.

Tool output drops and heat feels weaker mid-session

Voltage sag under sustained heating load causes the 18V rail to drop below the tool's regulation threshold, reducing heating element output. This is a contact resistance problem as often as it is a cell problem — check the battery bay terminals for oxidation or debris. Clean the contacts with isopropyl alcohol and reseat the pack firmly. If sag continues, check open-circuit voltage on the pack; a healthy cell should read at or above 20V fully charged.