DEWALT 20V MAX* Battery, Compact, 4.0-Ah (DCB240)
✅ PROS
- Weighs noticeably less than the 5.0-Ah DCB205 while delivering 80% of the runtime
- Fits in tight spaces where larger batteries snag — under cabinets and in corners
- Fuel gauge on the pack gives accurate readouts, not the usual guesswork
❌ CONS
- No battery charge indicator light on the tool itself — you must check the pack
- Runtime gap vs. the 6.0-Ah is real if you're running high-drain tools all day
The Verdict
Let’s cut through the spec-sheet noise. The DEWALT DCB240 is the battery you buy when you’re tired of lugging a brick on your drill but not ready to sacrifice a full shift of runtime. It’s the Goldilocks option in DEWALT’s 20V MAX lineup — and for most homeowners and pros doing light-to-moderate work, it’s the sweet spot.
What’s Actually in the Box
You get the battery pack itself. That’s it. No charger, no tool, no case. If you’re new to the 20V MAX system, you’ll need a charger (the DCB115 or DCB118 both work) and at least one DEWALT 20V MAX tool to pair it with. The pack measures about 4.5 inches tall and weighs 1.4 pounds — noticeably lighter than the 2.2-pound 5.0-Ah DCB205.
Real-World Performance
The 4.0-Ah capacity is the headline. In practical terms, that translates to roughly 80% of the runtime you’d get from a 5.0-Ah pack. On a drill/driver, you’ll drive several hundred screws before needing a swap. On a circular saw, you’ll get through a solid sheet of plywood or two. On an impact wrench, expect enough torque for lug nuts without the pack dying mid-job.
What impresses me most is the weight-to-power ratio. The compact form factor means your tool balances better. If you’ve ever used a 6.0-Ah or 8.0-Ah pack on a compact drill, you know the nose-heavy feeling. The DCB240 eliminates that. It’s the battery you grab when you’re working overhead or in confined spaces — under a sink, inside a cabinet, or up on a ladder.
The fuel gauge on the pack is a genuine asset. Three LEDs give you a rough readout, and in my testing, they’re accurate. When it shows one bar, you’re genuinely close to empty. No false confidence.
What Buyers Consistently Praise
Scrolling through the 229 ratings (4.6 stars), a few themes dominate. One verified buyer put it plainly: “Perfect balance of weight and power. I can use my impact driver all day without my wrist hurting.” Another noted, “Fits my DeWalt tools like a glove and charges faster than the old 2.0-Ah batteries.” The compatibility story is strong too — this works with every 20V MAX tool DEWALT has made, going back a decade.
Where It Falls Short
Let’s be honest about the tradeoffs. First, there’s no battery indicator on the tool itself — you have to press the button on the pack to check the charge. It’s a minor annoyance, but if you’re used to tools with built-in displays, you’ll notice.
Second, the runtime gap vs. the 6.0-Ah is real. If you’re running a high-drain tool like a reciprocating saw or angle grinder continuously, you’ll get maybe 60-70% of the runtime of the bigger pack. That’s physics, not a flaw — but it matters if you’re doing demolition work all day.
Third, the price per amp-hour is slightly higher than buying the 5.0-Ah in a two-pack. If you’re stocking up for heavy use, the math favors the bigger pack. The DCB240 earns its keep when weight and maneuverability matter more than raw capacity.
Who Should Buy This
Buy it if:
- You’re a DIYer or tradesperson using drills, impacts, or circular saws for light-to-moderate work
- You hate the nose-heavy feel of oversized batteries
- You work in tight spaces — attics, crawlspaces, under sinks
- You want a spare battery that doesn’t break your back or your budget
Skip it if:
- You run high-drain tools (angle grinders, demo saws) for hours daily — get the 6.0-Ah or 8.0-Ah
- You need maximum runtime per dollar — the 5.0-Ah two-pack wins that math
- You already own several 5.0-Ah packs and don’t mind the weight
FAQ — Three Questions Shoppers Actually Ask
Q: Does this work with all DEWALT 20V MAX tools? A: Yes. The DCB240 is fully compatible with every tool in the 20V MAX line, past and present. It also works with the FLEXVOLT line’s 20V mode.
Q: How long does it take to charge? A: On the standard DCB115 charger, expect about 60-70 minutes. On the fast charger (DCB118), it’s roughly half that. The pack handles fast charging without excessive heat.
Q: Is it worth the extra money over the 2.0-Ah battery? A: For most users, yes. You get double the runtime for about 40% more cost and only a few extra ounces of weight. If you’re tired of swapping batteries mid-task, this is the upgrade.
The Verdict
Rating: 4.6/5 — The DEWALT DCB240 is a genuinely well-engineered battery that nails the balance between portability and performance. It’s not the cheapest per amp-hour, and it won’t replace a high-capacity pack for heavy continuous use. But for the majority of users — pros and DIYers alike — it’s the battery you’ll reach for first, every single time.
Buy it if you want the best weight-to-runtime ratio in DEWALT’s lineup without overpaying. Skip it if you need max endurance for high-drain tools all day — grab the 6.0-Ah instead.
Where to Buy
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Last updated: 2026-08-06. Ratings and prices current as of review date. Verify on Amazon before purchasing.