my dewalt dcd800b drill just clicks when i pull the trigger, battery is charged but nothing spins.

Diagnosis

The rhythmic clicking sound you hear when pulling the trigger on the DCD800B is the electronic relay or the MOSFETs in the brushless controller attempting to engage the motor, but failing to sustain a current loop. Because this is a brushless model, it does not have traditional carbon brushes that wear out; instead, it relies on a sophisticated electronic control board that manages the permanent magnet motor. When you hear a click without rotation, the tool is receiving a "start" signal, but the circuit is being interrupted immediately, often triggering a safety shutdown to prevent a short circuit.

This is most frequently caused by a high-resistance connection at the battery interface or a "soft-lock" in the electronic controller. If the battery pins are not making a perfect 360-degree contact with the tool's terminals, the voltage may be high enough to trigger the switch (the click), but as soon as the motor demands high amperage to spin the chuck, the voltage drops instantly, breaking the connection. This can also happen if the drill has been exposed to heavy dust or metallic shavings that have migrated into the battery rail, creating a micro-gap between the terminals.

How to Fix It

To resolve this connectivity failure and reset the electronic controller, follow these precise steps:

1. Remove the 20V Max battery pack entirely from the base of the DCD800B.
2. Inspect the three copper-plated terminals inside the drill's battery port. Look for any "pitting" (small black burnt spots) or debris. If you see debris, use a can of compressed air to blow out the port from the top down.
3. Examine the battery terminals for any slight bending. The pins should be perfectly parallel; if one is pushed inward, it will not maintain the amperage needed for the brushless motor to kick over.
4. Take a clean, dry microfiber cloth and wipe the gold-plated contacts on the battery pack. If there is visible oxidation (a dull grey film), use a pencil eraser to gently scrub the contacts until they are shiny again.
5. Perform a "Hard Reset" of the controller: With the battery removed, pull the trigger and hold it for 5 full seconds. This drains any residual capacitance in the brushless control board.
6. Slide the battery back into the tool, ensuring you press down firmly until you hear a distinct, metallic "click" from the locking tabs. Give the battery a firm shake to ensure it is seated deep in the rail.
7. Test the trigger in "Speed 1" (low gear) first to see if the motor engages with lower torque.

If That Didn't Work

• Cross-Test with a Different Battery: The DCD800B is sensitive to voltage drops. If you are using an older 2.0Ah battery, try a high-capacity 5.0Ah or 6.0Ah battery. A failing cell in a smaller battery can provide enough voltage to "click" the switch but fail under the initial load of the brushless motor.
• Check the Forward/Reverse Toggle: Ensure the direction selector is pushed fully into one of the two positions. If the toggle is resting in the center "neutral" position, the trigger will often click or feel dead because the circuit is physically broken to prevent the tool from spinning.
• Inspect for Internal Gear Jam: If the click is accompanied by a very slight movement of the chuck, a piece of debris may be jammed in the planetary gear set. Try rotating the chuck by hand (with the battery removed) to ensure it spins freely. If it feels "notchy," there may be a mechanical failure in the gearbox.
• Check for Trigger Switch Contamination: If you have been drilling through drywall or masonry, fine dust can enter the housing and coat the trigger potentiometers. Use compressed air to blow directly into the gaps around the trigger switch to clear any insulating dust.

Heads Up

• Avoid Liquid Cleaners: Never use WD-40 or rubbing alcohol on the battery terminals; these can leave a residue that attracts dust or cause premature corrosion on the gold plating.
• Battery Seating: Always ensure the battery is fully clicked in. A "loose" battery causes arcing, which creates carbon scoring on the terminals and will eventually lead to a permanent failure of the tool's power rail.
• Thermal Shutdown: If the tool was used heavily right before the clicking started, the DCD800B's thermal protection may be active. Let the tool cool for 20 minutes before attempting to restart.
• Storage Tip: Store your batteries in a cool, dry place. Extreme cold can cause the battery's internal resistance to spike, leading to the "click-no-spin" symptom even if the battery indicator shows full charge.