after a cut, my saw smells really hot, like an electrical burning smell, is that normal?

Diagnosis

The Milwaukee M18 Fuel 16-inch Chainsaw (2727-20) utilizes a high-torque brushless motor designed to mimic the power of a gas saw. While a faint "warm electronics" scent is common after a long day of cutting, a sharp, acrid electrical burning smell indicates that the motor windings or the electronic speed controller (ESC) are overheating. This usually occurs when the motor is forced to draw maximum current (amps) for an extended period, causing the copper windings to reach temperatures that begin to degrade the insulating varnish. This condition is almost always caused by "mechanical drag." When the chain is dull, improperly tensioned, or the bar is bogged down in a heavy hardwood cut, the motor cannot maintain its optimal RPM. This forces the controller to pump more current into the motor to overcome the resistance. If you notice the saw "bogging down" or the chain speed slowing significantly during a cut, the resulting heat buildup can lead to permanent magnet degradation or a complete burnout of the control board.

How to Fix It

Follow these steps to eliminate the source of the heat and restore the saw to safe operating temperatures:

1. Immediate Shutdown: Remove the M18 battery pack immediately. Do not simply turn the switch to "Off"; physically disconnecting the power source prevents the controller from continuing to draw current while the unit is stationary.
2. Chain Sharpness Audit: Inspect every cutter tooth. If the top plate is rounded or the chrome is dull, the saw is "rubbing" rather than "cutting." Replace the chain or use a 5/32" round file to sharpen each tooth to a precise 30-degree angle.
3. Tension Adjustment: Check the chain tension. If it is too tight, it creates massive friction on the bar rails and puts an artificial load on the motor. The chain should snap back to the bar when pulled, but have enough play to be rotated by hand (while wearing gloves).
4. Bar Lubrication Check: Ensure the bar oil reservoir is full and that oil is actually reaching the chain. Dry friction on the guide bar creates heat that transfers directly back into the motor housing and sprocket.
5. Battery Verification: Ensure you are using a High Output (HO) battery. Using a standard 5.0Ah battery on a 16-inch bar in heavy timber can cause the battery to overheat, which in turn creates a burning smell from the battery's internal protection circuitry rather than the motor.

If That Didn't Work

• Inspect the Sprocket and Nose: Remove the bar and check the drive sprocket for metal shavings or "burrs." If the sprocket is damaged, it creates mechanical resistance that forces the motor to work harder. Clean out all packed sawdust and pitch from the sprocket cover using compressed air or a stiff brush.
• Verify Chain Grade: Ensure you are using the correct pitch and gauge chain. Using a chain that is slightly off-spec can cause it to bind on the bar, leading to excessive amp draw and electrical overheating.
• Check for Internal Debris: Use compressed air to blow out the motor vents. The 2727-20 has specific cooling ports; if these are clogged with fine sawdust or resin, the motor cannot dissipate heat, causing the electronics to bake even during light use.
• Test with a Smaller Bar: If the burning persists with a sharp chain, try a shorter bar (e.g., 10-inch). If the smell disappears, your current cutting application is exceeding the tool's thermal capacity, and you should incorporate "cooling breaks" every 15 minutes of active cutting.

Heads Up

• Avoid "Boring" Cuts: Do not force the saw into the wood. Let the chain speed do the work. If you have to lean your full weight on the saw, you are overheating the motor.
• Battery Matching: Always pair this saw with M18 High Output batteries (8.0Ah or 12.0Ah) for heavy-duty tasks to ensure the voltage doesn't sag, which reduces the strain on the motor controller.
• Oil Frequency: Check your bar oil every 3-4 cuts. A dry bar is the fastest way to overheat the drive system.
• Thermal Cutoff: If the saw stops abruptly and won't restart, it has hit its thermal protection limit. Do not attempt to restart it until the housing is cool to the touch.