DeWalt PowerStack 1.7Ah Battery Review: Small Pack, Serious Power

Introduction

Few recent cordless tool accessories have generated as much buzz as the DeWalt PowerStack. It arrived with a familiar 20V Max connection but an unfamiliar heart: a stack of lithium pouch cells instead of the cylindrical cells DeWalt has used for years. The pitch is simple, a battery with the punch of a full-size pack in a dramatically smaller body. The price of that compact size, however, is a genuine question worth answering before you spend money. Priced at $119, or around $132 delivered, it is not a casual purchase. We put it through runtime tests, impact wrench comparisons, and cold and hot weather trials to find out where it earns its keep and where it falls short.

What the PowerStack Actually Is

Inside the housing sits a compressed stack of five lithium pouches, each rated at 1.7 amp hours, connected in series to produce 18.5 volts, or 20 volts max. A common misconception is that these packs should be as tiny as the pouch cell in a phone, but a phone runs on roughly 3.7 volts, while DeWalt’s 20V line needs five cells in series. The result is still the most compact meaningful capacity option in the lineup: 1.7 amp hours total.

DeWalt now ships three different battery cell types: 18650s, 21700s, and lithium pouch. Understanding which is which matters, because they behave differently in ways that affect runtime, cold weather, and heat.

Power: The Headline Claim Holds Up

DeWalt talks about power constantly with this pack, and the testing bears it out. On a high-torque impact wrench, the PowerStack posted 630 foot-pounds, closely matching both a 5.0 amp hour 18650-based XR pack and a 4.0 amp hour 21700-cell compact. That aligns with earlier comparisons of single-row 21700 packs versus double-row 18650 packs, which have also shown essentially equal performance.

The PowerStack was, in fact, the most powerful battery tested across all temperatures on the high-torque wrench, peaking at 469 foot-pounds per second, or 421 foot-pounds on average across the run. It will not beat a 6.0 amp hour XR pack with 21700 cells in a 2P configuration, but it keeps pace with the similarly priced compact and standard XR options.

Runtime: The Trade-Off Nobody Hides

Capacity is the honest weak spot, and DeWalt has glossed over it. In a heat gun runtime test, the PowerStack died at the five and a half minute mark while the 5.0 amp hour pack ran for 17 minutes. That is almost exactly the threefold difference you would expect from three times the capacity, so the rating is accurate, it just isn’t advertised.

In practical terms, you get the same power with roughly half or a third of the runtime, depending on the comparison pack. That trade makes sense for some tools and not others.

Cold and Hot Weather Performance

Batteries of all types behave differently at temperature extremes, so the three packs were chilled overnight to around 7 to 10 degrees Fahrenheit (negative 13 Celsius) and tested on the high-torque wrench.

The frozen 5.0 amp hour pack was the worst performer, dropping from 629 to 422 foot-pounds, a loss of one third, turning the tool into something closer to a mid-torque. The frozen 4.0 amp hour compact scored 447, edging out the 5.0 late in the run, possibly because its smaller mass warms up faster during a long pull. The PowerStack managed 476, the best of the cold group, though still well below its room-temperature 630.

One caveat: a separate tester has reported more difficulty with a cold PowerStack than a cold traditional battery, so cold-climate users should treat this with some caution. Hot testing told a different story. Packs heated to around 140 to 145 degrees Fahrenheit (61 Celsius) all posted slightly elevated numbers, with the hot PowerStack at 645, splitting the difference between the other two types.

Where It Makes the Most Sense: Compact Tools

The clearest use case is compact tools used away from the body. On the DeWalt DCF921 Atomic compact impact wrench, the PowerStack delivered 333 foot-pounds, a solid increase over the 5.0 pack, lifting the tool’s average power ranking from 246 to 260. On tools like the DCF850 impact driver and the DCF921, the shorter pack makes the tool noticeably easier to maneuver in tight spaces.

Anyone who has run a bulky 6.0 amp hour pack on a small impact or drill knows how tiring that gets. The PowerStack solves that without sacrificing the power those tools need.

Buying Advice

For small impacts and drills used overhead or in awkward positions, the PowerStack is a genuine win: full-size power in a pack that stays out of the way. For saws, heat guns, or any tool you run for long stretches continuously, the shortened runtime is harder to live with, and a larger XR pack remains the better pick.

It is also worth noting that the PowerStack line currently consists of a single 1.7 amp hour option. A higher-capacity pouch pack, something like a 4.0 amp hour version, would broaden its appeal considerably, but for now this one size is all that exists.

Conclusion

The DeWalt PowerStack delivers on its core promise: power that closely matches 5.0 amp hour XR and 4.0 amp hour compact packs in a far smaller, lighter body. Its weaknesses are equally clear, one third of the runtime, a single capacity option, and mixed cold weather reports. If your priority is compact handling on small tools, it is an easy recommendation. If runtime matters more than size, stick with the larger packs. Either way, pouch-cell technology looks like the direction this platform is heading, and that is genuinely exciting.