Drill won't turn on with a charged battery: six checks in order

You pull the trigger and nothing happens. The pack shows full, the charger said it was done, and the tool sits there like a brick. Before you order a battery or drive to a service center, work the problem in order. Most no-start cases are contact, cutoff or wrong-platform problems, and all three are cheap to rule out.

Each check below has a result you can see or feel, so you know when you have found it.

Step 1: Reseat the pack and watch the latch

Pull the pack out and push it back until you hear the click. Not a firm push, an actual click.

Then rock it gently side to side. Play means the latch is worn or the pack is not fully seated. Many tools will not close the circuit unless the pack sits that last two millimeters.

Look into the bay with the pack out. Sawdust packed into the pocket is the most common cause of a pack that will not seat. Blow it out, check that the tabs at the back of the bay spring back, and try again.

If the tool fires, you are done. Clean the bay, and note this will keep happening until you stop dropping the tool in the dirt.

Step 2: Check the terminals on both sides

With the pack out, look at the contacts inside the tool and the contacts on the pack. Both should be clean, bright metal and springy.

What you are looking for:

• Black or green discoloration on either side. That is corrosion, and it blocks current. A pencil eraser or a swab with contact cleaner handles light cases.
• A tab that stays flat when you press it. Tool-side tabs are spring loaded; one that does not spring back will not press against the pack.
• A burn or melted spot near a contact. Stop here. That is arcing from a loose connection, and a pack with a scorched contact should come out of service.
• Battery terminals not contacting cleanly. Sawdust and drywall dust are not conductive, but they hold the contacts apart.

Seat the pack and try the trigger after cleaning. If it runs, you found it. A stutter means contact is intermittent, not absent, which is progress.

Step 3: Test the pack in a second tool

This is the fastest way to split the problem in half. Put the pack in a different tool on the same platform and pull the trigger.

If the second tool runs, the pack is fine and the fault is in the first tool. If it also does nothing, the pack is the suspect. With no second tool, measure across the main contacts instead: a nominal 18V pack should read around 19V to 20V charged, a 12V pack around 12V to 12.6V.

A pack that reads zero volts with a full gauge has a protection board that latched off. Some recover on the charger. Do not open the pack to reset it.

If the pack is the suspect and it is out of warranty, a 6.0Ah M18 replacement pack is the cheaper way to confirm the diagnosis than a new tool.

Step 4: Check the tool's switch and trigger

If the pack runs another tool, the fault is in the tool, and the switch is the first suspect. Triggers on modern drills are sealed electronic modules, but the linkage in front of them fails.

Listen while you pull the trigger slowly. You should hear a small click from the switch body. No click suggests the trigger is not reaching the switch, which happens after a drop or after grit works into the pivot. A click with no motor response points to the switch electronics or the connection between switch and motor.

One more thing: the forward/reverse selector. A tool left between positions, or knocked partway, can sit in a neutral that opens the circuit. Snap it fully to one side and try again. Same for the clutch collar, which on some models has a lockout at the end of travel.

Step 5: Rule out thermal cutoff and the overload it came from

A power tool sudden stop mid-cut, with no restart, is often thermal protection. The board in the pack or the tool shut down because a cell or the motor got too hot, and it will not reset until the temperature drops.

Feel the pack. If it is warm, set it in the shade for fifteen to twenty minutes. Feel the motor housing too.

A thermal cutoff is not a fault; the tool is protecting itself, and it usually means a dull bit or too much pressure on a large hole. Repeated cutoffs on light work point to a cell problem: a pack with high internal resistance heats up under loads a healthy pack would shrug off.

If the tool cut out and the pack is cold, skip ahead.

Step 6: Confirm you are on the right voltage platform

This one sounds obvious until it happens to you. Two packs can share a slide fit and not share a voltage.

• Compact versus standard. Some subcompact platforms look like their bigger siblings but will not drive the larger tools.
• Generation changes. Bosch's 14.4V and 18V lines are the classic example, where part numbers that look related are not interchangeable.
• Adapters. A third-party adapter adds a connection, and every added connection is a place for voltage to drop.
• Makita's 10.8V and 12V labels. Same three-cell platform, two names, endless confusion at replacement time. The Makita 12V CXT guide explains the naming.

If the pack fits but the tool does nothing, check the pack's nominal voltage against the tool's rating plate. A 12V pack in an 18V tool is a wrong voltage platform: it may fit the slide but will not spin the motor.

Common mistakes

Buying a new pack first

The pack is the expensive part and the least likely culprit. Terminals and seating cause more no-starts than dead cells do.

Forcing a pack that does not seat

If it needs a shove, the latch or the bay is wrong. Forcing it bends the tool-side tabs and turns a five-minute fix into a repair.

Opening the pack

Tool packs are sealed assemblies, and the cells are not replaceable. Inside there are exposed cell tabs at full pack voltage.

Ignoring a hot pack

A pack that gets hot on light work is failing. Keep running it and a warranty conversation becomes a fire risk.

Assuming the charger is honest

A charger showing green can have delivered almost nothing if the pack's thermistor is faulty.

Testing with a pack you have not charged

It happens. Charge it until the light says done, then run the checks.

If the charger is the suspect rather than the tool, diagnosing a pack that will not charge works through that side. Dirty contacts cause more of these than failed cells, covered in cleaning battery terminals.

FAQ

Why does my drill click but not spin? A battery clicks but the tool does not run, usually because the switch closed and the motor is not getting current: worn brushes, a failed switch module, or a pack that cannot supply inrush.

Can a battery show full charge and still be dead? Yes. The gauge reads voltage, not capacity, and a pack with high internal resistance can show a healthy resting voltage and collapse the moment the motor draws current.

How do I reset a tool's thermal cutoff? Let it cool. A tool thermal cutoff reset happens on its own once the cell or motor temperature drops, usually in fifteen to twenty minutes. There is no button.

What if the pack works in one tool but not another? The fault is in the second tool: terminals, switch, or a voltage mismatch. Clean the bay, check the tabs, and confirm both are on the same platform.

When should I stop and buy a replacement? When the pack fails in every tool, reads far below nominal voltage after a full charge, or shows a scorched contact. At that point a replacement costs less than a repair.

Sources

• DeWalt Product & Tool Support (battery and charger troubleshooting): dewalt.com/support
• DeWalt support, charger and battery troubleshooting (a pack must be fully seated for charging to start): dewalt.com/support
• Family Handyman, "Why You Should Own More Than One Battery System for Cordless Tools": familyhandyman.com
• r/Tools, community troubleshooting threads: reddit.com/r/Tools

If the pack is the problem, the Milwaukee-compatible collection is a starting point for M12 and M18 replacements, and the charger collection covers units that will not misread a good pack.