A Bosch drill that won't start is a common problem and is usually caused by something simple like a battery, charger, or switch issue rather than a major fault. Most causes can be checked and fixed at home in a few minutes with basic tools.
Common causes of bosch drill won't start
- Flat, faulty, or incorrectly fitted battery
- Battery contacts or terminals dirty or corroded
- Charger not working or battery not fully charged
- Safety lock or forward/reverse switch left in the wrong position
- Worn or damaged trigger switch
- Internal fault such as worn carbon brushes (corded models) or a tripped thermal cutout
How to diagnose and fix it
- Check the battery charge Remove the battery and place it on the charger. Confirm the charger light behaves as expected (usually solid green when charging, then a different colour when full). If the charger shows no light at all, try a different power outlet.
- Inspect and clean the battery contacts Look at the metal contacts on both the battery and the drill body. Wipe away any dust, grease, or corrosion with a dry cloth or a pencil eraser, then refit the battery firmly until it clicks.
- Test with a spare or known-good battery If you have access to another compatible Bosch battery, fit it and try the drill again. This quickly confirms whether the battery or the drill itself is at fault.
- Check the forward/reverse and lock switch Make sure the direction switch is set fully to one side, not left in the central safety-lock position. Slide it firmly left or right and try the trigger again.
- Test the trigger switch Squeeze the trigger fully and listen for any clicking or buzzing. A weak or intermittent click can indicate a worn switch that needs replacing.
- Let the drill cool down If the drill has been used heavily, it may have tripped an internal thermal cutout. Leave it to cool for 15–20 minutes before trying again.
- Check corded models for brush wear On corded Bosch drills, worn carbon brushes can prevent starting. If you're comfortable doing so, check the brushes are not worn below the recommended length and replace them if needed.
When to call a professional
If the drill still won't start after trying a known-good battery, cleaning the contacts, and checking the switches, the fault is likely internal, such as a damaged motor, wiring fault, or failed switch assembly. In this case, it's best to take the drill to an authorised Bosch service centre rather than opening the casing yourself, as this can void the warranty. Stop immediately and seek professional help if you notice burning smells, smoke, or visible damage to the casing or cord.
FAQ
Why does my Bosch drill battery show charge but the drill still won't start?
A charged battery doesn't guarantee good contact or a working switch. Clean the contacts, confirm the battery clicks in securely, and check the direction switch isn't stuck in the central lock position.
Can a Bosch drill be fixed if the trigger switch is broken?
Yes, trigger switches are a common replacement part and are usually available from Bosch service centres or authorised parts suppliers, though fitting is best left to a professional if you're not confident with electrical repairs.
How do I know if it's the battery or the drill that's faulty?
Try the suspect battery in another compatible tool, or try a different known-good battery in the drill. If the battery works elsewhere but the drill still won't start, the fault lies with the drill.
