Black & Decker 20V MAX* POWERCONNECT 4.0 Ah Battery

A bigger tank for the POWERCONNECT stable

I’ve been running Black+Decker’s 20V tools for years, mostly on the compact 1.5 Ah and 2.0 Ah packs. The first weekend with the 4.0 Ah POWERCONNECT battery felt like switching a subcompact’s gas tank for a full-size. I didn’t change the way I worked; I just stopped thinking about swapping batteries.

Over several weeks of home and yard projects—assembling a cedar planter, trimming hedges, sanding a door, and blowing off the driveway—I used the 4.0 Ah pack across a drill/driver, hedge trimmer, quarter-sheet sander, and a compact blower. The experience is largely what I hoped for: longer runtime, predictable performance, and clean integration across the POWERCONNECT lineup.

Compatibility and setup

This pack slides onto every 20V POWERCONNECT tool I own with a positive, confident latch. The easy-release tab is chunky enough to hit with gloved hands, and it hasn’t snagged in a pocket or on a tool belt. If you’re already in the platform, it’s plug-and-play.

One thing to keep in mind: a charger is not included. With the standard compact wall charger, a fully depleted pack took most of an evening to top off. On Black+Decker’s faster charger, my charge times were just under two hours from empty. If you’re stepping up to higher-capacity batteries, investing in the faster charger is worthwhile.

Build quality and design

The housing feels robust and the pack is well sealed against dust, though it isn’t rated for water exposure. I wouldn’t hesitate to use it outdoors, but I also wouldn’t leave it sitting in wet grass. The shell has enough rubberized texture to grip, yet it still slides cleanly into tight battery bays.

Weight measured 1.50 lb on my scale. On a compact drill, that makes the tool a little bottom-heavy versus a 1.5 Ah, but not awkward. On the hedge trimmer and blower, the added mass smooths out vibration and actually improves balance.

There’s no battery fuel gauge. That’s the one design omission I felt during longer sessions. You’ll learn to read your tools’ behavior (most taper power slightly, then cut out), but an onboard indicator would make planning easier.

Performance and runtime

Let’s talk expectations. A 4.0 Ah pack should deliver roughly double the runtime of a 2.0 Ah under similar loads, and in my use, that’s exactly what happened.

• Drill/driver: Driving 3-inch construction screws into SPF studs, I drove just over 200 screws across multiple sessions before the pack called it quits. Power delivery stayed consistent; I didn’t see the drill bog in the last 10% of the charge.

• Hedge trimmer: On a mixed privet and holly hedge, I worked for a long, unbroken stretch that would have required two swaps with a 2.0 Ah. I stopped for me, not for the battery.

• Sander: Continuous sanding is a good thermal and endurance test. After about 40 minutes of non-stop work on a painted door, the battery was warm but not hot. I hit thermal shutdown once by being overly stubborn during a heavy draw; after a short cool-down, it resumed without complaint.

• Blower: At high speed, runtime landed in the “finish the whole driveway” zone for me. With lighter sweeping in the garage and patio, it spanned multiple short sessions.

For folks who like to think in watt-hours, a quick clarification: Black+Decker labels these as 20V MAX, with a nominal voltage of 18V. Using nominal numbers, 4.0 Ah equates to about 72 Wh. Some product literature lists 80 Wh (using max initial voltage) and I’ve also seen 60 Wh referenced. Based on the runtimes I’m seeing, real-world energy feels right around that 70-ish Wh mark—exactly what I’d expect for this capacity at nominal voltage.

Electronics and thermal behavior

The pack includes onboard protection that monitors voltage and temperature. In practice, that means you get a clean cutoff rather than limping performance when it’s depleted, and you’ll see the tool stop if the pack is getting too warm. I intentionally pushed it with the sander and a compact circular saw. I could trigger a thermal timeout only with sustained, continuous draws that most casual users won’t replicate. It cooled quickly and recovered without any lingering performance issues.

During the first couple of charges, I noticed a faint “new electronics” smell near the charger. The pack itself stayed cool to the touch and the odor didn’t persist. Since then it’s been uneventful—no swelling, no unusual heat, and no surprises.

Charging and care

Because there’s no fuel gauge, I got into the habit of rotating packs at natural breaks rather than running them flat. Lithium-ion chemistry prefers partial charges and dislikes extreme heat. A few practical tips that have kept my packs healthy:

• Don’t store fully empty; aim for 40–60% if you’ll shelve it for a while.
• Avoid leaving it on the charger for days; top off and remove.
• Keep it out of direct summer sun (truck beds can get very hot).
• Brush off debris before charging so the pack can shed heat.

If you own the slow wall charger, plan your workflow or grab a second battery. With the faster charger, a single 4.0 Ah pack plus a compact backup covered me for all-day DIY.

Ergonomics across tools

• Drill/driver: Noticeably more endurance without compromising control, though it does make compact drills feel less “featherweight.”
• Hedge trimmer: Big quality-of-life improvement. The extra runtime means fewer mid-trim stops.
• Sander: Heavier than a compact pack, but the steadier power and longer sessions outweigh the ounce count for me.
• Blower: Feels better balanced with the bigger battery; less pulsing at the end of the charge.

Fitment was solid on every tool I tried—no rattles, no intermittent contacts, and zero accidental unlatching.

Reliability and warranty

After many cycles, capacity feels consistent and the pack holds charge well on the shelf. The two-year limited warranty is reassuring, and Black+Decker has been around long enough that service and parts are straightforward to find.

One note on purchasing: make sure the pack you’re buying is a genuine POWERCONNECT unit. Look for clear Black+Decker branding and the model designation on the label. If a listing’s photos don’t match the branding or model you expect, choose another seller. Authentic packs have been more consistent for me in fit, thermal behavior, and longevity.

What could be better

• A built-in fuel gauge would meaningfully improve user experience.
• Include clearer watt-hour labeling based on nominal voltage to avoid confusion.
• The standard wall charger is painfully slow for a 4.0 Ah pack; pairing with the rapid charger feels essential.

None of these are deal-breakers, but they’re worth factoring into your buying decision.

Who benefits most

• Homeowners invested in POWERCONNECT who want fewer battery swaps.
• Weekend DIYers tackling medium projects—decking, fencing, landscaping—where consistent runtime matters.
• Anyone using higher-draw tools in the lineup (blowers, saws, sanders) that can overwhelm compact packs.

If you only use a drill for occasional shelf installs, a smaller, lighter battery remains a fine match. For everything else, this 4.0 Ah pack is the sweet spot.

Recommendation

I recommend the 4.0 Ah POWERCONNECT battery for anyone already in Black+Decker’s 20V ecosystem who needs longer runtime without adding complexity. It delivers the capacity bump it promises, integrates cleanly with the tools and chargers, and manages heat and protection gracefully. Pair it with the faster charger, pick up a second pack if you work in long stretches, and you’ll spend more time getting things done and less time babysitting batteries. The lack of a fuel gauge and the slow standard charger are the only real blemishes on an otherwise dependable, worthwhile upgrade.