the battery seems to die super fast on this saw compared to my other makita tools, like it's draining in minutes

Diagnosis

The Makita XRJ05Z is a high-draw tool by design, but rapid battery depletion—specifically when a 5.0Ah or 6.0Ah LXT battery drains in just a few minutes—is usually a symptom of "mechanical drag." In a reciprocating saw, the motor has to fight not only the material you are cutting but also the internal friction of the stroke mechanism. When a blade becomes dull or "loaded" with pitch and resin, the motor cannot maintain its optimal RPMs. To compensate, the tool's electronic controller pulls significantly more current (amps) from the battery to maintain torque, which converts electrical energy into heat rather than cutting action. You can confirm this by observing the tool's behavior: if the saw requires excessive downward pressure to make a cut, or if the blade shoe is vibrating violently against the workpiece, the motor is overworking. Additionally, check the battery terminal contacts for carbon buildup or debris; a poor connection creates electrical resistance, which causes the battery to heat up and report a lower voltage level to the tool, triggering a premature low-battery shutdown even if the cells still have capacity.

How to Fix It

To restore battery efficiency and cutting speed, follow these precise steps to optimize the mechanical load on the XRJ05Z motor:

1. Blade Audit: Remove the current blade. Inspect the teeth for rounding or missing chunks. If you are cutting pressure-treated lumber or hardwoods, check for resin buildup. Replace the blade with a high-TPI (Teeth Per Inch) blade for metal or a low-TPI coarse blade for demolition wood. Use a genuine Makita or Diablo carbide-tipped blade for maximum efficiency.
2. Shoe Adjustment: Ensure the tool's shoe is pressed firmly against the material. If there is a gap between the shoe and the workpiece, the saw will bounce. This "chatter" wastes immense amounts of battery power through vibration rather than forward progress.
3. Terminal Cleaning: Use a cotton swab dipped in 90% isopropyl alcohol to clean the gold-plated terminals inside the tool's battery slot and on the battery itself. Remove any sawdust or metallic shavings that may be causing voltage drops.
4. Load Management: Adjust your cutting technique. Instead of forcing the saw through the material, let the tool reach full speed before engaging the cut and use light, steady pressure. If the motor slows down significantly, back off for a second to allow the electronic controller to stabilize.

If That Didn't Work

• Test with a High-Capacity Battery: The XRJ05Z is an 18V tool, but it performs significantly better with the 5.0Ah or 6.0Ah LXT batteries. If you are using a 2.0Ah or 3.0Ah battery, the "voltage sag" under load will make the tool feel like it is dying rapidly. Swap to a 6.0Ah battery to see if the runtime stabilizes.
• Check for Internal Gear Friction: If the saw sounds "grindy" or feels sluggish even with a brand-new blade and no material, the internal grease may have dried out or been contaminated with sawdust. This increases the mechanical load on the motor. In this case, the tool requires a professional teardown and re-lubrication of the reciprocating drive.
• Battery Cell Imbalance: If the battery dies quickly in the saw but works fine in a drill, one of the cells in that specific battery pack may be failing (voltage imbalance). Try a different LXT battery pack to determine if the issue is the tool or the power source.
• Overheating Shutdown: Ensure the motor vents are clear of debris. If the tool overheats, the internal thermal protection may throttle the power or shut down the tool, which can be mistaken for a dead battery. Use compressed air to blow out the motor housing.

Heads Up

• Blade Matching: Never use a fine-tooth metal blade to cut thick wood; the sawdust will clog the gullets, creating massive friction and draining your battery in record time.
• Heat Warning: If the battery casing feels hot to the touch, stop immediately. Overheating the LXT cells during high-draw applications can permanently reduce the battery's total capacity.
• Shoe Maintenance: Periodically check the screws holding the shoe in place. A loose shoe causes the tool to oscillate, which wastes energy and wears down the motor bearings prematurely.
• Storage: Store your LXT batteries in a cool, dry place. Extreme cold can increase internal resistance, leading to faster perceived drain during heavy-duty use with the XRJ05Z.