DeWalt 20V MAX Premium Lithium-Ion 4.0Ah Battery Pack (2 Pack)

Why I added the 4.0Ah pack to my kit

I’ve been building out a cordless workflow around DeWalt’s 20V MAX line for years, and I wanted a battery that could bridge the gap between compact 2.0Ah packs and the heavier high-capacity options. The 4.0Ah pack hits that middle ground nicely. It pairs well with drills, impact drivers, oscillating tools, and nailers without making them feel nose-heavy, while still giving enough runtime to work through a half-day of moderate tasks. The two-pack format is practical—one on the tool, one on the charger—so I can keep moving without waiting on a charge cycle.

Build and ergonomics

Each pack weighs about 1.4 lb, which is light enough to keep compact drivers and multi-tools balanced. The housings are solid, with the familiar DeWalt fit and finish: tight seams, rigid plastic, and clean terminals. The latch engages positively with every 20V MAX tool I own, and the batteries slide into chargers without fuss.

The 3-LED fuel gauge is one of those small features that solves an everyday annoyance. It’s accurate enough to plan the next task and avoid swapping too early. On a busy day I’ll tap the indicator while walking from the saw to the drill and decide whether to finish one more operation or grab the spare.

Runtime and performance

Capacity isn’t just about how long a battery runs; it’s also about how consistently it delivers power under load. In my tools, the 4.0Ah pack keeps a steady pace through most medium-demand tasks:

• Impact driver: Plenty of runtime driving structural screws and ledger bolts, with less noticeable voltage sag toward the end of the charge compared to compact packs.
• Drill/driver and hammer drill: Enough stamina to handle a couple dozen 1/2-in holes in SPF and plenty of pilot drilling without abruptly falling off a cliff.
• Oscillating multi-tool: Markedly longer runtime over 2.0Ah packs, especially in sanding and flush-cutting where constant power matters.
• Recip saw and circular saw: It’ll do the job, but this is where the limitations show. Cross-cutting dimensional lumber or demo work eats through 4.0Ah faster; if heavy saw work is your norm, a 5.0Ah or 6.0Ah pack would be more appropriate.

Compared with DeWalt’s compact 2.0Ah batteries, the 4.0Ah pack gave me roughly double the useful runtime in most of my work, with a minor weight penalty. Compared with 5.0Ah packs, I trade a little runtime for better balance and slightly faster recovery in the charger. It’s a smart middle option for general carpentry and punch list work.

Charging and battery management

On a standard 20V MAX charger, I consistently see a full recharge in about an hour and a half. That aligns with the listed 90-minute charge time and fits nicely into a work rhythm: drain one pack, swap to the second, and by the time the second is nearly done, the first is ready. Faster chargers shave that time, but even on the basic units the turnaround is predictable.

These packs hold charge well on the shelf. I’ve pulled one after a couple weeks in a cold garage and still had useful capacity on the job. Extreme cold will sap performance (as with any lithium-ion), but I haven’t had thermal shutdowns or surprise drop-offs. In summer heat, they get warm on high-demand tools, but not alarmingly so, and recovery is quick once they’re out of the tool.

Compatibility across the platform

I’ve used these across a spread of 20V MAX tools and chargers without any compatibility quirks. They seat securely in older drills and newer brushless tools alike. If your kit includes a mix of compact and full-size tools, the 4.0Ah pack is versatile enough to live on a driver or a nailer most of the time and pinch-hit on a saw in a pinch.

Durability on the job

Between truck boxes, site dust, and the occasional drop from a sawhorse, these packs have held up. The housings resist scuffs and the labels remain legible. The terminals stay clean and tight, and the latches haven’t loosened. I haven’t experienced intermittent connections, and the LED indicators still function like day one.

I also like that DeWalt backs the pack with a multi-year service agreement and an easy return window. It adds some peace of mind given how hard batteries get used compared to the tools themselves.

Where 4.0Ah fits in the lineup

Battery choice is about matching capacity and weight to your most common tasks:

• 2.0Ah: Lightest, best for overhead and finish work, but short runtime.
• 4.0Ah: The sweet spot for all-day use on drivers, drills, oscillating tools, and nailers. Enough muscle for occasional saw work.
• 5.0Ah and up: Better for demo, recip, circular saws, grinders, or full-day production. Heavier on small tools and slower to charge.

If your day is a mix of drilling, driving, and trim, the 4.0Ah pack feels right. If you spend hours cutting or grinding, step up in capacity.

Everyday usability

A few small touches add up:

• The LED gauge saves time and reduces guesswork.
• The weight keeps compact tools nimble without feeling toy-like.
• The two-pack format aligns with a realistic work cadence—one working, one charging.
• Low self-discharge means less babysitting when tools sit for a week.

One caveat: there’s no charger in the box. That’s common for battery-only packs, but if you’re new to the platform, plan on buying a charger separately.

Tips to get the most out of it

• Rotate packs: Use and charge them in pairs to balance wear.
• Mind the temperature: Let hot packs cool before charging; keep cold packs warm before heavy loads.
• Don’t store fully depleted: Park them around half to three-quarters if they’ll sit for a while.
• Keep contacts clean: A quick brush or blast of air helps maintain a solid connection.
• Use the gauge: Swap before you hit the last bar to avoid a sudden stop mid-cut.

Value and who it’s for

For tradespeople and serious DIYers who want longer runtime without turning compact tools into anchors, this pack makes strong sense. It’s also a cost-effective way to expand a kit: two batteries cover most day-to-day work, and you can add a single higher-capacity pack later if you find yourself on saws or grinders more often.

If you already own several 5.0Ah or larger packs and prefer the extra runtime over lighter weight, you may not reach for the 4.0Ah as often. Conversely, if you’ve been living on 2.0Ah packs, this will feel like your tools just got a bigger fuel tank with minimal penalty.

The bottom line

I recommend the 4.0Ah two-pack for most 20V MAX users who need reliable, all-day performance on drills, drivers, oscillating tools, and nailers without the heft of the biggest batteries. The combination of solid build quality, accurate fuel gauges, predictable 90-minute charge times, and low self-discharge makes them easy to live with. They’re not the best fit if your daily work leans heavily on high-draw saws or grinders—larger-capacity packs are better there—but as a general-purpose backbone for a cordless setup, this two-pack is a smart, dependable choice.