As an Amazon Associate I earn from qualifying purchases.Updated: March 18, 2026
The Battery 20V Max is the power source for your DeWalt DCS391 tool, enabling it to cut, grind, or perform other tasks. Like all batteries, its capacity diminishes over time. Delaying replacement can lead to reduced performance, shorter runtimes, and eventually complete device failure. Replacing the battery restores original functionality.
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Function: Provides cordless power to operate the DeWalt DCS391 tool.
Signs it needs replacing: Reduced runtime, slower performance, needing frequent recharges even when fully charged.
OEM vs aftermarket: OEM batteries (DeWalt branded) offer guaranteed compatibility and quality but are typically more expensive. Aftermarket options can be cost-effective but always verify compatibility with your specific model (DCS391B).
Installation: Battery replacement is usually straightforward, involving simply removing the old battery and clicking the new one into place.
Replacement schedule: every 2-4 years
Compatibility warning: always verify part number matches your exact model before ordering
Pros & Cons
Pros
✓ Restores device to original performance without buying a new unit
✓ Significantly cheaper than a full device replacement
✓ Multiple options available from OEM and aftermarket sellers
Cons
✗ OEM parts cost more than third-party alternatives
✗ Wrong part number will not fit — model verification is essential
Common Use Cases
Scheduled maintenance: replacing on the every 2-4 years schedule
Performance restoration after noticing reduced output or efficiency
Preventive replacement before a worn part causes secondary damage
Who Should Buy This
This replacement battery is ideal for DeWalt DCS391 owners whose tool is experiencing reduced power or runtime. It's a cost-effective solution to extend the life of your device.
Not ideal for: If your DeWalt DCS391 has suffered significant damage or other malfunctions beyond just battery wear, a full device replacement might be more appropriate.
Good to Know Before Buying
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Always confirm your exact model number (DCS391B) before ordering. Part numbers vary between model variants and production years. Check the label on your device or original documentation to be sure.
Frequently Asked Questions
What is the part number for the DeWalt DCS391 Battery 20V Max?
The part number is DCB204. Always verify this matches your exact model (DCS391B) before ordering, as similar models may use different parts.
How often should I replace the Battery 20V Max on my DeWalt DCS391?
every 2-4 years
Will aftermarket Battery 20V Max replacements work in my DeWalt DCS391?
Third-party parts are widely available and often cheaper than OEM. Look for listings that specifically mention compatibility with model DCS391B and check buyer reviews for fit confirmation before purchasing.
Prices change frequently. See the latest deal on Amazon.