3.7V Mannesmann M17480 Cordless Screwdriver Replacement Battery

My Mannesmann screwdriver stops halfway through driving a screw and then starts again after I wait — what's causing that?

That's thermal cutoff triggering, and on a 3.6V Li-ion cell this small it happens faster than most people expect — especially when driving self-tapping screws into hardwood or dense material where the motor stalls briefly under load. The cell heats up, the protection circuit opens, and the tool goes dead until it cools. Set the torque clutch one step lower than you think you need and let the tool do the work without forcing it; stalling the motor even for a second is what spikes the heat. If it keeps cutting out on light tasks like assembling flat-pack furniture, put a multimeter on the battery contacts after a cutoff — you want to see above 3.2V resting; below that the cell is genuinely depleted, not just hot.

The charger finishes in about ten minutes and the battery goes flat after three or four screws — did I get a dead battery?

A 3.6V Li-ion cell that charges in ten minutes hasn't actually charged — the charger has either detected a fault and quit early, or the cell voltage was already sitting near nominal and the charger read it as full. A healthy charge cycle on this capacity should take noticeably longer than that. Before assuming the cell is dead, leave it on the charger for a full uninterrupted cycle, then check the resting voltage at the battery contacts — a properly charged 3.7V Li-ion should read between 4.1V and 4.2V. If it reads under 3.8V straight off the charger, the cell isn't accepting a full charge and needs replacing.

New replacement battery fitted but the screwdriver feels weaker than it used to — torque is noticeably lower than the original

A fresh Li-ion cell often needs two or three full discharge-and-charge cycles before it delivers its rated capacity and voltage under load — this is normal cell conditioning, not a fault. On a compact 3.6V tool like this, even a small voltage sag under load (the difference between 3.7V open-circuit and 3.4V under a stalled screw) translates to a noticeable drop in torque. Run the battery down fully on light tasks, charge it completely, and repeat that cycle twice before drawing any conclusions. After conditioning, if the clutch still feels like it's slipping at settings where it didn't before, check that the replacement cell's contact terminals are seating flush — a partial connection increases resistance and kills torque.