chainsaw starts but then stops after a few seconds of cutting, like it's overheating or something. battery is full.

Diagnosis

The DeWalt DCCS620B features an integrated Electronic Overload Protection (EOP) system designed to protect the brushless motor from permanent thermal damage. When the saw shuts down mid-cut despite a full battery, the motor controller has detected a current spike—essentially an "amp draw" that exceeds the safe operating threshold. This happens when the resistance against the chain is greater than the motor's torque capacity can handle without overheating the internal windings. This is rarely a battery failure and almost always a mechanical resistance issue. If the chain is dull, the teeth "rub" rather than "slice," creating massive friction that spikes the motor's temperature in seconds. Similarly, if the chain tension is too tight, it creates excessive drag on the drive sprocket. You can confirm this by running the saw in open air; if it runs indefinitely without cutting wood but shuts down the moment it hits a log, the EOP is functioning correctly and the issue is external to the motor electronics.

How to Fix It

To resolve the overload shutdowns, you must reduce the mechanical load on the brushless motor by optimizing the cutting edge and drive system.

1. Cool-Down Period: Power down the tool and remove the 20V Max battery. Wait at least 10 minutes. The EOP will not reset instantly; the internal thermistor must reach a baseline temperature before the controller allows the motor to engage again.
2. Chain Sharpening: Inspect the cutters. If the chrome finish on the cutting edge is gone or rounded, use a 5/32" (4.0mm) round file specifically designed for 3/8" low-profile chain. File from the inside out, maintaining the original factory angle (typically 30 degrees). Ensure each tooth is filed equally to prevent the saw from pulling to one side, which increases friction.
3. Tension Adjustment: Loosen the bar nut slightly. Pull the chain tight against the bar; there should be a small gap (about 1/16") between the drive link and the bar rail. If the chain is "guitar-string" tight, it puts immense pressure on the sprocket, triggering the overload sensor. Tighten the nut firmly but do not over-torque.
4. Bar Lubrication Check: Ensure the bar oil reservoir is full. Check that the oil holes in the bar are not clogged with sawdust. A dry bar creates immense heat and friction, which contributes to the thermal cutoff.
5. Cutting Technique: Avoid "forcing" the saw. Let the chain speed do the work. If you have to push the saw hard into the wood, you are overloading the motor.

If That Didn't Work

• Swap the Chain: If sharpening doesn't help, install a brand new 16" low-profile chain. Sometimes chains develop "micro-fractures" or lose their temper (hardness) due to overheating, making them impossible to sharpen effectively. A fresh chain often eliminates the amp-spike issue.
• Inspect the Drive Sprocket: Remove the side cover and check the drive sprocket for burrs or accumulated debris. If the sprocket is worn or clogged with pitch and sawdust, the motor has to fight the drive system before it even hits the wood. Clean it with a wire brush and a bit of solvent.
• Test with a High-Capacity Battery: While you mentioned the battery is full, try a 5.0Ah or 9.0Ah XR battery if you are using a 2.0Ah. Lower capacity batteries can suffer from "voltage sag" under heavy load, which the tool may interpret as a power failure or overload condition.
• Check for Bar Rail Wear: Inspect the guide bar for "burrs" (small metal lips) along the edges. Use a flat mill file to remove these burrs. If the chain is rubbing against a damaged rail, it creates significant drag.

Heads Up

• Avoid "Burying" the Bar: Never cut with the tip of the bar or bury the entire 16" length into a thick log. This creates maximum friction and is the fastest way to trigger the EOP.
• Oil Every Time: Never run the DCCS620B without bar oil. The brushless motor is efficient, but the friction of metal-on-metal will heat the bar to the point where the chain expands and loses tension.
• Clean the Vents: Use compressed air to blow out the motor housing vents. If sawdust builds up inside the casing, the motor cannot dissipate heat, causing the thermal cutoff to trigger much sooner than it should.