just got this drill and the battery seems to die way faster than my old m18 drill, is something wrong with it?

Diagnosis

The perceived battery drain in the Milwaukee M18 FUEL 2904-20 is typically not a defect in the tool, but a result of the vastly increased power density and current draw compared to older M18 brushless or brushed models. The 2904-20 utilizes a high-performance brushless motor designed to deliver significantly higher torque (up to 1,200 in-lbs) and higher RPMs. To achieve this, the tool pulls a much higher amperage from the battery cells during peak load. If you are using the same battery packs that you used with your older, less powerful drill, you are likely experiencing "voltage sag." Because the FUEL motor demands more current, the internal resistance of older or lower-capacity batteries causes the voltage to drop more rapidly under load. This triggers the tool's electronic protection system to signal a low battery state much sooner than it would in a lower-draw tool, even if the battery technically has remaining chemical energy. To confirm this, test the drill with a brand new High Output (HO) battery; if the runtime increases significantly, the issue is battery impedance and capacity, not a tool malfunction.

How to Fix It

To maximize the runtime and efficiency of your 2904-20, follow these steps to optimize your power setup:

1. Upgrade to High Output (HO) Cells: Replace standard XC batteries with M18 High Output batteries (e.g., the M18 REDLITHIUM High Output 6.0Ah or 12.0Ah). These cells are specifically engineered with a lower internal resistance to handle the high amp-draw of FUEL tools without premature voltage drop.
2. Verify Battery State of Charge: Ensure you are using a Rapid Charger (model 48-11-1161) rather than an older standard charger. The Rapid Charger ensures a more complete saturation of the cells, which is critical for the high-demand 2904-20 motor.
3. Adjust Torque Settings: Stop using the drill in the highest gear/torque setting for every task. Use the adjustable clutch ring to set the torque to the minimum required for the fastener. This prevents the motor from drawing maximum current unnecessarily.
4. Optimize Trigger Control: Avoid "hammering" the trigger. The electronic variable speed trigger on the 2904-20 is designed for a gradual ramp-up. Sudden full-throttle bursts create massive current spikes that drain the battery faster than a steady, controlled application of power.

If That Didn't Work

• Test with a Different Battery Pack: If you are using a single 5.0Ah battery, try a 12.0Ah HD battery. If the 12.0Ah battery still dies rapidly, the tool may have a short in the trigger assembly or a faulty motor controller (ECM) that is causing an abnormal current draw.
• Inspect for Mechanical Binding: Check the chuck for any debris or misalignment. If the chuck is binding or the drill is being forced to operate at an angle, the motor will work harder to overcome the friction, drawing significantly more power from the battery.
• Check for Thermal Throttling: If the tool feels excessively hot to the touch, the internal thermal protection may be limiting performance, which can sometimes feel like a loss of power or "dying" battery. Allow the tool to cool and check if the runtime stabilizes.
• Verify Battery Terminal Contact: Inspect the gold-plated terminals on both the battery and the tool. If there is carbon buildup or debris, it creates resistance, which causes a voltage drop that tricks the tool into thinking the battery is empty. Clean them with a dry cloth or a small amount of isopropyl alcohol.

Heads Up

• Avoid Deep Discharge: Never run your M18 batteries until the tool completely stops. This can damage the cells and permanently reduce the runtime of your packs.
• Temperature Matters: Lithium-ion batteries perform poorly in temperatures below 32°F (0°C). If you are working in a cold environment, keep your batteries in a warm bag or pocket until the moment you use them to prevent rapid voltage drop.
• Storage Voltage: If storing the tool for more than 30 days, keep the battery at approximately 50-70% charge rather than 100% to preserve the long-term health of the cells.
• Match Tool to Battery: Remember that "FUEL" tools are designed for High Output batteries. Using "Compact" (2.0Ah) batteries in a 2904-20 will result in extremely short runtimes and may cause the battery to overheat.