jigsaw randomly shuts off mid-cut then comes back on when i release the trigger, battery is full.

Diagnosis

The Bosch GST18V-60CN features an integrated electronic overload protection system designed to prevent the brushless motor and circuitry from permanent failure. When the tool shuts off mid-cut and resets immediately upon releasing the trigger, you are experiencing a "thermal trip" or a current-spike shutdown. This occurs when the motor encounters resistance that exceeds the pre-set amperage threshold of the control board, causing the system to cut power to protect the windings from melting. This is most commonly caused by "binding," where the blade becomes pinched in the kerf, or by using a blade with a tooth pitch that is too coarse for the material thickness, leading to excessive friction. Because the GST18V-60CN is a high-torque tool, it can often force a cut even when the blade is dull, but the electronic sensors detect the massive increase in current draw required to maintain the stroke speed and trigger the shutdown to prevent a burnout. You can confirm this by checking if the tool's housing feels hot to the touch near the motor vents or if the shutdown occurs specifically when you apply more forward pressure.

How to Fix It

To resolve the intermittent power loss and restore consistent cutting performance, follow these precise steps:

1. Remove the battery pack immediately to ensure the tool is fully powered down before servicing.
2. Inspect the current blade. If you see "burnt" teeth or a blackened edge on the blade, it is dull. Replace it with a high-TPI (teeth per inch) blade for thinner materials or a specialized "Clean for Wood" blade for the GST18V-60CN to reduce friction.
3. Clean the sawdust out of the motor vents. Use compressed air to blow out the cooling slots on the side of the tool housing; if these are clogged, the electronic protection will trip much faster due to heat buildup.
4. Check the blade clamp mechanism. Ensure the blade is seated fully and locked tight. A slipping blade creates vibration that can trigger the electronic protection.
5. Reinsert the battery and perform a test cut. Instead of pushing the tool forward, apply light, steady pressure. Let the orbital action and the motor speed create the chip; if you feel the tool slowing down, back off the pressure immediately.
6. Adjust your cutting speed. If you are cutting dense hardwood or thick plastic, reduce the stroke speed slightly to prevent the blade from overheating and binding in the material.

If That Didn't Work

• Check for battery terminal oxidation. If the gold-plated contacts on the 18V battery or the tool's receiver are dirty or pitted, the tool may experience momentary voltage drops under load, which the tool interprets as a power failure. Clean the contacts with a cotton swab dipped in 90% isopropyl alcohol.
• Test with a different 18V battery pack. If you are using a low-capacity 2.0Ah battery, the tool may be hitting the "voltage sag" limit during heavy cuts. Switch to a 4.0Ah or 6.0Ah ProCORE18V battery to provide a more stable current flow under high load.
• Inspect the base plate (shoe) for flatness. If the shoe is not sitting flush against the material, the tool will tilt, causing the blade to bind sideways in the cut. This lateral friction spikes the amperage and trips the ECO system.
• Examine the internal drive gear lubrication. If the tool has been used in extremely dusty environments, the grease in the gear housing can become contaminated with grit, increasing internal mechanical resistance. This requires a professional teardown to clean and re-grease the planetary gears.

Heads Up

• Avoid "forcing" the cut. If the tool begins to bog down, it is a signal from the motor to slow your feed rate; ignoring this leads to premature electronic failure.
• Always match your blade to the material. Using a coarse rip blade for a fine finish cut increases the likelihood of the blade grabbing the material and triggering a shutdown.
• Keep the tool's vents clear. The GST18V-60CN relies on airflow to keep the control board cool; operating the tool in a pile of sawdust will trigger the thermal protection much sooner.
• Avoid using the tool at maximum speed for extended periods in very hard materials, as this generates heat faster than the cooling system can dissipate it.