drill seems weak on a fresh battery, struggles with basic 3 inch screws where it used to be fine

Diagnosis

The issue you are experiencing with the Makita XFD131 is likely a phenomenon known as "surface charge" or high internal resistance within the 18V LXT battery pack. While the battery indicator shows a full charge, the individual lithium-ion cells are unable to maintain the necessary voltage drop under a heavy mechanical load, such as driving a 3-inch screw. This causes the motor to starve for current, resulting in a perceived loss of torque and "weakness" despite the battery being technically "full." To confirm this, perform a load test. If the drill operates at full speed when spinning in the air but slows down significantly or cuts out the moment the screw tip bites into the wood, the battery is failing to deliver peak amperage. If the drill is weak even without a load, the issue is likely a worn carbon brush in the motor or a slipping planetary gear in the transmission, though the XFD131's robust gear set makes battery failure the primary suspect in 90% of these cases.

How to Fix It

To isolate and resolve the power loss, follow these precise steps to determine if the battery is chemically exhausted or if the tool requires mechanical service:

1. Cross-Battery Validation: Remove the suspect battery and insert a known-good, high-capacity 18V LXT battery (preferably a 5.0Ah or 6.0Ah pack). Attempt to drive the same 3-inch screw into the same material. If the drill recovers its full power, the original battery has reached the end of its cycle life.
2. Voltage Reset Cycle: If you only have one battery, perform a deep discharge. Run the drill under a moderate load (not a full stall) until the tool completely stops. Do not force it to stall, as this can trip the internal thermal protector.
3. Controlled Recharge: Place the battery on a DC18RC or DC18RC fast charger. Ensure the contacts are clean of sawdust or debris. Charge the battery until the green light indicates a full charge.
4. Clutch Setting Verification: Check the torque adjustment ring at the front of the XFD131. Ensure it is not accidentally set to a low number (1-5). Rotate the ring to the "Drill" icon (the bit symbol) to ensure the motor is delivering maximum torque without the clutch slipping.
5. Gear Selection: Confirm the speed selector switch on top of the tool is set to "1" (Low Speed/High Torque) for 3-inch screws. Setting it to "2" provides more speed but significantly less driving power.

If That Didn't Work

If the drill remains weak across multiple batteries and correct settings, try these advanced solutions:

• Inspect the Chuck Jaws: Debris trapped in the keyless chuck can cause the bit to slip or create excessive friction. Open the chuck fully, use compressed air to blow out the interior, and re-tighten the bit firmly. A loose bit often feels like a weak motor.
• Check for Motor Brushes: The XFD131 uses brushed motors. If the tool is several years old, the carbon brushes may be worn down to the limit. Remove the motor housing screws and inspect the brushes; if they are shorter than 5mm, replace them with a genuine Makita brush set to restore electrical conductivity.
• Gearbox Lubrication: The planetary gears may have lost their grease or the grease may have hardened. Carefully open the gear casing and apply a small amount of high-temperature lithium grease to the planetary gear set to reduce internal friction.
• Battery Terminal Cleaning: Use a cotton swab dipped in 90% isopropyl alcohol to clean the gold-plated terminals on both the battery and the tool's base. Oxidation or sawdust buildup can create resistance, limiting the current flow to the motor.

Heads Up

• Avoid "Stall-Outs": Never force the drill to a complete stop while the trigger is pulled; this creates a massive current spike that can permanently damage the battery cells and overheat the motor windings.
• Temperature Management: Lithium-ion batteries lose significant discharge capacity in temperatures below 40°F (4°C). If working in a cold garage, keep your batteries inside the house until the moment you need them.
• Storage Voltage: Never store your LXT batteries completely dead for long periods. This can lead to "deep discharge" where the cells drop below the critical voltage threshold, rendering the battery unchargeable by the standard charger.
• Avoid Generic Packs: Be wary of "high capacity" third-party batteries. They often lack the high-discharge cells required for high-torque applications, leading to the exact "weakness" you are currently experiencing.