saw suddenly lost power mid-cut, sounds weak now even with fresh batteries.

Diagnosis

The sudden loss of power in the Makita XSR01Z is typically caused by the triggering of the Electronic Overload Protection (EOP) system. This system monitors the current draw and temperature of the brushless motor. When you hit a dense knot or force the saw too hard through a thick piece of lumber, the controller detects a spike in amperage and "throttles" the motor to prevent the windings from melting or the batteries from overheating. If the saw sounds "weak" or "sluggish" even after a battery swap, the tool has likely entered a thermal protection state where it will not return to full RPM until the internal sensors detect a significant drop in temperature. Another common cause for this specific model is a mechanical bind in the blade guard or a buildup of resin and sawdust in the gear housing. Because the XSR01Z uses a high-torque brushless system, any physical resistance—such as a bent blade flange or a jammed guard—forces the motor to work harder, triggering the power-limiting circuitry. You can confirm this by removing the blade and running the saw; if the motor screams at full speed without the blade attached, the issue is either the blade's condition or the material you are cutting. If it still sounds weak without a blade, the internal controller is likely stuck in a protection loop or there is a failure in the battery contact terminals.

How to Fix It

Follow these steps to reset the tool and restore full power output:

1. Complete Power Cycle: Remove both 18V batteries immediately. Leave the tool unpowered for at least 20 minutes. This allows the capacitors in the motor controller to discharge and the thermal sensors to reset to their baseline state.
2. Clear the Mechanical Path: Use compressed air to blow out the motor vents and the area around the lower blade guard. Ensure the guard snaps back instantly; if it lingers, lubricate the pivot point with a dry silicone spray.
3. Blade Inspection: Remove the blade using the provided wrench. Inspect the teeth for "burnt" tips or missing carbide. A dull blade increases friction, which triggers the EOP. Replace the blade with a high-quality 36V-rated circular saw blade.
4. Terminal Cleaning: Inspect the battery terminals on the saw. If there is sawdust or carbon buildup, clean them using a cotton swab dipped in 90% isopropyl alcohol. Ensure the terminals are springy and not recessed.
5. The "Soft Start" Test: Reinsert two fully charged 18V batteries. Instead of plunging directly into a workpiece, run the saw in open air for 10 seconds to let the brushless controller synchronize. Perform a shallow "skim cut" on a piece of soft pine to verify that the torque has returned.

If That Didn't Work

• Battery Pairing Mismatch: Ensure you are using two identical battery capacities (e.g., two 5.0Ah batteries). If you mix a 2.0Ah with a 5.0Ah, the tool may detect a voltage imbalance and limit power to protect the smaller cell, resulting in a "weak" sound.
• Check for Blade Warp: If the blade is slightly warped, it will rub against the inner guard or the base plate during the rotation. This creates constant drag that mimics a motor failure. Swap to a brand new blade to rule out centrifugal warping.
• Inspect the Gearbox Oil: If the saw has been used heavily in high-heat environments, the gear lubricant may have thinned or leaked. If you see oil residue on the base plate, the gears may be overheating, causing the tool to throttle power to prevent gear seizure.
• Controller Failure: If the tool remains weak across multiple battery sets and with no blade installed, the internal PCB (Printed Circuit Board) or the Hall effect sensors in the brushless motor may have failed. This requires a professional teardown to check for burnt capacitors on the control board.

Heads Up

• Avoid "Forcing" the Cut: The XSR01Z is powerful, but forcing the saw through a cut causes the motor to draw excessive amps, which shortens the lifespan of the electronic controller. Let the blade speed do the work.
• Battery Heat Management: Do not charge your batteries immediately after a heavy session where the tool throttled. Let the batteries cool to room temperature to avoid damaging the lithium cells.
• Blade Selection: Always use blades designed for high-RPM cordless saws. Using a low-quality or "budget" blade increases friction and heat, which is the primary trigger for the power-loss issue.
• Dust Removal: Regularly blow out the motor vents. Sawdust buildup acts as an insulator, trapping heat inside the motor housing and triggering the thermal overload much sooner than necessary.