DeWalt PowerStack vs FLEXVOLT Compatibility: What Fits What (and What Doesn't)

Both PowerStack and FLEXVOLT batteries share the same DeWalt 20V MAX battery foot, so both run any 20V MAX tool and charge on any 20V MAX charger — including third-party USB chargers and inverters that mount on that foot. The difference is one-directional: FLEXVOLT also switches to 60V (and pairs to 120V) for FLEXVOLT-specific tools. PowerStack only ever runs at 20V MAX. So FLEXVOLT can do everything PowerStack can, plus more — while PowerStack is purpose-built for lighter, faster-cycling 20V MAX work.

The Short Answer: Compatibility at a Glance

The table is the whole story. Everything below explains *why* — and which battery you should actually be reaching for on a given tool.

Why PowerStack and FLEXVOLT Are Compatible — Same 20V MAX Foot

Both battery lines use the same slide-on connection that DeWalt introduced with the 20V MAX platform. Same keyways, same contacts, same latch points. That's why a battery you bought five years ago still fits a tool you bought last month.

This is by design — DeWalt's entire ecosystem play is backward and forward compatibility within the 20V MAX footprint. PowerStack and FLEXVOLT both honor that.

The Voltage-Switching Trick FLEXVOLT Does That PowerStack Doesn't

FLEXVOLT packs contain cells wired in a switchable configuration. When the battery seats on a 20V MAX tool, it connects in parallel and delivers 20V MAX (nominal 18V). When it seats on a 60V FLEXVOLT tool, the connection switches to series and delivers 54V nominal (marketed as 60V MAX). Two packs can also pair in certain FLEXVOLT tools to reach 108V nominal — marketed as the 120V MAX configuration.

PowerStack has no such switching. It's a fixed 20V MAX (nominal 18V) pack, full stop.

Form Factor: Pouch Cell vs 21700 Cylindrical

This is where the two lines diverge physically. PowerStack uses lithium-ion pouch cells — the same geometry you find in phones and laptops. Flatter cells, lower internal resistance, and a more stable discharge curve. Less voltage sag when you hit a tough fastener or a dense cut.

FLEXVOLT uses 21700 cylindrical lithium-ion cells. These are physically larger than the 18650 cells in older DeWalt packs, which is part of why FLEXVOLT packs carry so much capacity. The trade-off is size and weight — a 9Ah FLEXVOLT pack is noticeably heavier and taller than any PowerStack.

PowerStack 5.0Ah in particular deserves a call-out: DeWalt rates the DCBP315 at 50% more power compared to standard 20V MAX battery technology, thanks to POWERSTACK's pouch-cell design — and it achieves that in roughly the same general footprint as a conventional DeWalt 5.0Ah pack, without the extra bulk you'd expect from the output.

Does PowerStack Work on a FLEXVOLT Tool?

Short answer: depends on the tool's voltage requirement.

On 60V or 120V FLEXVOLT Tools: No

A FLEXVOLT circular saw, miter saw, or table saw requires the pack to switch into 60V mode. PowerStack can't do that. Seat a PowerStack on a dedicated 60V FLEXVOLT tool and the tool won't run — there's no 60V on tap. The battery isn't damaged; the tool simply won't start.

On FLEXVOLT-Branded Tools That Accept 20V MAX: Rare, But Yes

A small number of tools carry FLEXVOLT branding but are designed to run on 20V MAX batteries. If a tool's label or manual confirms "20V MAX compatible," then yes — PowerStack runs it. These are uncommon. Check the tool spec before assuming.

Does FLEXVOLT Work on a 20V MAX Tool?

Yes, every time. Seat a FLEXVOLT pack on any 20V MAX tool and it auto-steps down to 20V. The tool sees it as a standard 20V MAX battery. No adapter needed, no settings to change.

The Trade-Off: Weight and Bulk

A FLEXVOLT 9Ah pack is substantially heavier than a PowerStack 5.0Ah. On a compact impact driver or drill, that changes the balance of the tool in a way that gets tiring fast. For sustained overhead work or single-handed use, running a FLEXVOLT 9Ah on a 20V MAX impact just to avoid a battery swap is a bad ergonomic trade.

When You'd Actually Want to Run FLEXVOLT on a 20V MAX Tool

On high-draw 20V MAX tools — a larger-format circular saw, a grinder running continuously, or a heavy-duty reciprocating saw — the FLEXVOLT pack's extra capacity earns its keep. You're not fighting balance as much on two-handed tools, and the extended runtime between swaps matters. If you're already carrying FLEXVOLT packs for a 60V saw, running one on your heavy-draw 20V tools makes sense. Dedicated PowerStack packs for the drills and impacts, FLEXVOLT for the saws.

Chargers: What Charges What

Standard DeWalt 20V MAX Chargers

Both PowerStack and FLEXVOLT charge on standard DeWalt 20V MAX chargers. The DCB115 and DCB118 are each compatible with both PowerStack and FLEXVOLT packs, and the DCB1106 charges 12V MAX, 20V MAX, and FLEXVOLT 20V/60V MAX batteries — all sharing the same physical foot and communication protocol.

FLEXVOLT Fast Charger (DCB118)

For large FLEXVOLT packs — 9Ah, 12Ah, 15Ah — the DCB118 is the charger to use if charge time matters. It delivers higher current and is rated for FLEXVOLT spec charge rates. PowerStack packs also charge on it without issue, though you won't see any benefit over a standard charger since the PowerStack packs are smaller.

Third-Party USB Chargers and Inverters: Both Work

Any accessory that mounts on the 20V MAX battery foot works with both PowerStack and FLEXVOLT — because both batteries seat identically and both output 20V MAX to accessories.

The USB-C fast charger charges USB devices up to 65W and includes both USB-C and USB-A ports. Snap it onto a PowerStack 1.7Ah and you've got a compact USB power source in a jacket pocket. Snap it onto a FLEXVOLT 9Ah and you've got a serious on-site charging hub. Works either way.

The power inverter with dual USB puts a 120V outlet and two USB ports on whatever 20V MAX battery you happen to have at hand. Both PowerStack and FLEXVOLT seat on it — confirmed by the product specs ("Supports all Dewalt 20V batteries"). Run it off a FLEXVOLT 12Ah if you need extended runtime, or a PowerStack 5.0Ah if you just need to charge a phone and keep moving.

Which Battery Belongs on Which Tool

This is the question the spec sheets don't answer for you.

PowerStack 1.7Ah: Compact Tools, All Day

The DCBP034 is for your impact driver, compact drill, and oscillating tool. Light enough that you forget it's there. The pouch-cell chemistry means less voltage sag, so the tool doesn't bog on the last bit of charge the way older compact packs do. Not for runtime — for feel and responsiveness.

PowerStack 5.0Ah: Mid-Draw Tools, Better Balance

The DCBP315 fits the same space as a conventional 5.0Ah pack but delivers more consistent power output under load. Drills, larger impacts, brushless circ saws in the 6.5" range. If you're running a standard 20V MAX 5.0Ah on these tools and finding they bog mid-cut, the PowerStack is a real step up without adding size.

For a deeper look at how PowerStack stacks up against the standard 20V MAX lineup, see the PowerStack vs standard 20V MAX batteries breakdown.

FLEXVOLT 9Ah / 12Ah / 15Ah: High-Draw and 60V Tools

Any dedicated 60V FLEXVOLT tool — sliding miter saw, worm-drive circ saw, table saw — gets a FLEXVOLT pack, full stop. Beyond that: if you're running a 20V MAX angle grinder for sustained cuts, a large reciprocating saw through structural lumber, or any high-draw tool where runtime is the constraint, step up to a FLEXVOLT pack.

The 6Ah sits at the smaller end of the FLEXVOLT lineup — reasonable if you need a bit more than PowerStack 5.0Ah without going full heavy-pack. The 9Ah and up are for tools that earn the weight.

FAQ

Can I use a PowerStack battery on a FLEXVOLT tool? Only on FLEXVOLT-branded tools that specifically accept 20V MAX batteries — and those are uncommon. On any dedicated 60V or 120V FLEXVOLT tool, PowerStack won't deliver the voltage needed to start the tool.

Can I use a FLEXVOLT battery on a 20V MAX tool? Yes. FLEXVOLT automatically steps down to 20V MAX when seated on a 20V MAX tool. The only trade-off is extra weight and a bulkier pack profile.

Do PowerStack and FLEXVOLT use the same charger? Yes — both fit any standard DeWalt 20V MAX charger (DCB115, DCB1106, DCB118). For fastest charge times on large FLEXVOLT packs (9Ah and up), use the DCB118.

Is PowerStack more powerful than FLEXVOLT? Per-cell, PowerStack delivers more consistent power with less voltage sag, thanks to pouch-cell chemistry and lower internal resistance. But FLEXVOLT has more total capacity per pack and adds 60V/120V capability that PowerStack doesn't have.

Is PowerStack worth it over a standard 20V MAX 5Ah? For tools that bog under load and for better balance on compact tools — usually yes. For pure runtime per dollar, a standard 20V MAX 5.0Ah XR is still the cheaper option. See the PowerStack vs standard 20V MAX batteries comparison for the full details.

Will a PowerStack work with my existing 20V MAX charger? Yes. Any DeWalt 20V MAX charger charges it. So do third-party USB chargers and inverters built for the 20V MAX foot — like the ones we stock.

Can I use FLEXVOLT in a DeWalt 20V USB charger or inverter? Yes. Any accessory that mounts on the 20V MAX foot — including USB chargers and inverters — accepts FLEXVOLT, since FLEXVOLT seats and operates as a 20V MAX battery when connected to 20V MAX accessories. Same goes for PowerStack.

Both batteries, one platform foot. Whatever pack is in your bag, the same USB charger and inverter that runs off your standard 20V MAX battery runs off it too. Browse the DeWalt accessories lineup — the USB-C fast charger and the power inverter fit either battery without a second thought.

Image credits

• "DeWALT 12V Cordless Screwdriver" by Charles & Hudson — licensed under CC BY-SA 2.0 · via Flickr