Short answer: no — a Black+Decker® 20V MAX™ battery will not click onto any train horn gun directly, because nobody builds a horn with a Black+Decker-compatible mount. The good news is that the pack itself is electrically the same 18-volt class as the batteries our horns already run on, so you have three workable paths — and one of them costs less than a spare battery.
The Short Answer: No Native Mount, Three Workable Paths
A battery train horn gun is a compressor and a set of trumpets built around a power-tool battery mount. Each version of the horn ships with one specific mount: Milwaukee® M18™, DeWalt® 20V MAX™, Ryobi® ONE+™, Makita® LXT™, Craftsman® V20™, Bosch® 18V, Ridgid®, Bauer®, and a few others. Black+Decker's 20V MAX line — sold under the POWERCONNECT™ name — is not one of them. The pack's rails, latch, and terminal layout don't match any of those mounts, so it physically will not connect, even though the voltage inside is right.
That leaves a Black+Decker owner with three realistic options:
- The adapter route: order a horn built for DeWalt® 20V MAX batteries and add a third-party Black+Decker-to-DeWalt adapter. Your existing packs power the horn through the adapter.
- The universal DIY kit: a trumpet-and-manifold kit that attaches to a cordless drill you already own, so the battery mount question disappears entirely.
- A dedicated pack: buy the horn in the battery mount you want long-term and pick up one compatible battery for it.
Before we walk through each, it's worth understanding why the obvious assumption — "Black+Decker and DeWalt are the same company, so the batteries must swap" — fails.
Same Parent Company, Different Battery Mount
The confusion here is completely reasonable. Stanley Black & Decker owns DeWalt, Craftsman, Porter-Cable®, and Black+Decker, and both Black+Decker and DeWalt market their packs as "20V MAX." On paper they even measure the same: 20 volts maximum initial voltage off the charger, 18 volts nominal under load. That is the identical voltage class as a Milwaukee M18 pack — the marketing math is the only difference.
But the mechanical interfaces are deliberately different. The rails and connection tabs sit in different positions on each brand's pack, so a Black+Decker battery will not slide onto a DeWalt tool or vice versa. It isn't an engineering accident; each brand keeps its own battery ecosystem, and Black+Decker's POWERCONNECT system is aimed at light-duty homeowner tools while DeWalt's packs feed the higher-draw jobsite line.
It goes further than those two brands. Craftsman V20 packs — also made under Stanley Black & Decker — use a different contact-slot layout than Black+Decker and Porter-Cable packs, so even those siblings don't interchange without an adapter. The takeaway for horn shopping: shared voltage means nothing without a shared mount. That's exactly why every horn we sell is listed by the battery platform it accepts.
Option 1: An Adapter on a Horn Built for DeWalt® Batteries
Because Black+Decker and DeWalt packs run the same nominal 18 volts, third-party adapters that let a Black+Decker 20V MAX battery power DeWalt 20V MAX tools are widely sold on Amazon, eBay, and dedicated adapter shops. The adapter is a simple mechanical bridge: your Black+Decker pack slides into the top, and the bottom has DeWalt-style rails that click into the tool — or into the horn's DeWalt-compatible mount. There's no voltage conversion happening, because none is needed.
On the horn side, the natural pairing is the 5-trumpet horn gun for DeWalt® 20V MAX batteries, which also comes with a wireless remote, or the dual-trumpet version if you want something more compact. Both take standard DeWalt-style 20V MAX rails — which is what the adapter's underside mimics.
The adapter route works, but go in with eyes open:
- It's one-directional. A Black+Decker-to-DeWalt adapter only lets Black+Decker packs feed DeWalt-mount devices. It won't do the reverse, and a DeWalt-to-Black+Decker adapter is a different product.
- Never charge through an adapter. Adapter makers are explicit about this: remove the battery and charge it only on its original Black+Decker charger.
- Quality varies. These are unlicensed third-party accessories. Cheap ones can have weak contact pressure, which matters when a horn compressor pulls hard on the trigger. Stick to adapters with solid reviews and copper contacts.
- It adds stack height. The adapter puts roughly an inch between the pack and the horn grip — noticeable on a handheld unit, irrelevant on a mounted one.
We covered the general pros and cons of this approach across all brands in our cross-brand adapter guide, but the summary is: fine as a bridge for packs you already own, not the setup we'd recommend building around from scratch.
Watch the Amp-Hours: POWERCONNECT™ Packs Run Small
There's a second catch that has nothing to do with the mount. Black+Decker sells its 20V MAX line mostly in 1.5Ah and 2.0Ah capacities, sized for drills, string trimmers, and dustbusters. A 1.5Ah pack at 18 volts nominal stores about 27 watt-hours; a 5.0Ah jobsite pack stores about 90. The horn's compressor doesn't care which brand feeds it, but a small pack simply holds fewer blasts, and a hard-working compressor will sag a light-duty pack faster than a drill ever would.
You'll still get full loudness on a healthy 1.5Ah or 2.0Ah pack — the trumpets and compressor set the volume, not the battery brand — just expect fewer honks between charges. We broke down how many blasts you get per amp-hour if you want the numbers.
Options 2 and 3: Skip the Adapter Entirely
If you'd rather not stack an unlicensed adapter under a horn, there are two cleaner setups.
The universal DIY kit. Our DIY train horn kit with four trumpets takes the battery question off the table: it's a trumpet, manifold, and hardware package rated up to 150 dB that runs off a cordless drill you already own. If your garage is full of Black+Decker gear, your existing drill becomes the power unit and your existing packs keep doing their job — no adapter, no new battery ecosystem.
A dedicated pack on the mount you actually want. If you're going to spend money anyway, consider spending it on one battery for the platform the horn is built around instead of on an adapter. The loudest configuration we make is the 5-Trumpet Horn Gun for Milwaukee® 18V Battery — five trumpets, wireless remote option, and it runs on any M18-style pack, which is one of the easiest batteries to find new or used in the US. One 2.0Ah pack and a charger is all the horn needs, and your Black+Decker tools stay untouched.
FAQ
Is a Black+Decker® 20V battery the same as a DeWalt® 20V MAX battery?
Electrically, they're the same class: 20 volts maximum initial, 18 volts nominal, lithium-ion. Mechanically, no — the rails and contact positions differ, so the packs don't interchange between the two brands' tools or mounts without a third-party adapter, even though Stanley Black & Decker owns both brands.
Can I charge my Black+Decker battery through the adapter?
No. Adapters are for discharge only. Pull the pack out of the adapter and charge it on the original Black+Decker charger it came with. Connecting an adapter to any charger risks damaging the pack.
Do Craftsman® V20 batteries fit the same tools as Black+Decker packs?
No. Despite sharing a parent company, Craftsman V20 packs use a different contact-slot layout than Black+Decker 20V MAX packs, and the two don't interchange directly. If your garage runs on Craftsman V20, you don't need any adapter — the quad horn gun for Craftsman® V20 batteries takes those packs natively.
Will the horn be quieter running on a Black+Decker pack through an adapter?
Not meaningfully, as long as the pack is healthy and the adapter has solid contacts. Loudness comes from the compressor and trumpet count. What a small 1.5Ah pack does cost you is blast count per charge, and a worn pack or a sloppy adapter can slow how quickly pressure builds between blasts.
Will you make a horn with a native Black+Decker mount?
Demand decides the lineup, and Black+Decker owners are exactly who the adapter route and the DIY kit exist for today. If a native mount ships, it will appear in the store alongside the other brand-specific versions.