Sixteen tool-battery platforms will run a portable train horn today — and the pack already sitting on your charger is almost certainly one of them. This is the full chart: every brand, what its voltage label really means, and which sound tiers you can get for it.
The chart: every tool-battery brand and the horn tiers it runs
BossHorn builds a dedicated battery dock for each platform below, so your pack clicks straight in — no adapter, no wiring, no air tank. The columns on the right show which sound tiers are available for each system: Dual (130 dB, two trumpets), Quad (140 dB, four trumpets), and the Extreme/Boss class (150 dB+ premium quads).
| Battery platform | Label on the pack | Actual (nominal) voltage | Dual 130 dB | Quad 140 dB | Extreme/Boss 150 dB+ |
|---|---|---|---|---|---|
| Milwaukee M18 | 18V | 18V | Yes | Yes | Yes |
| DeWalt 20V MAX | 20V | 18V | Yes | Yes | Yes |
| Ryobi 18V ONE+ | 18V | 18V | Yes | Yes | Yes |
| Makita 18V LXT | 18V | 18V | Yes | Yes | Yes |
| Bosch 18V | 18V | 18V | Yes | Yes | Yes |
| Ridgid 18V | 18V | 18V | Yes | Yes | Yes |
| Craftsman V20 | 20V | 18V | Yes | Yes | — |
| Bauer 20V | 20V | 18V | Yes | Yes | Yes |
| Hart 20V | 20V | 18V | Yes | Yes | Yes |
| Hercules 20V | 20V | 18V | — | Yes | — |
| Porter-Cable 20V MAX | 20V | 18V | — | Yes | Yes |
| Worx 20V PowerShare | 20V | 18V | — | Yes | — |
| Skil PWRCore 20 | 20V | 18V | — | Yes | — |
| BLACK+DECKER 20V MAX | 20V | 18V | — | Yes | — |
| Kobalt 24V MAX | 24V | 21.6V | — | Yes | — |
| Flex 24V | 24V | 21.6V | — | Yes | — |
Two things jump out of that table. First, the Quad column is solid: every one of the 16 platforms gets at least the 140 dB four-trumpet horn, so nobody is stuck with a compromise model just because they bought into a less common battery system. Second, the “actual voltage” column is nearly identical from top to bottom — and that’s not a typo. More on that next.
18V vs 20V MAX vs 24V: what the label actually tells you
Here’s the part of the chart that surprises people. A lithium-ion cell sits at roughly 3.6 volts nominal and about 4 volts fresh off the charger. Nearly every tool pack on the chart is built from five of those cells in series: five times 3.6 is 18 volts working voltage, and five times the fresh-charge peak is where the “20V MAX” sticker comes from. Milwaukee, Makita, Ryobi, Bosch, and Ridgid print the working number on the pack; DeWalt, Craftsman, Bauer, Hart, Hercules, Porter-Cable, Worx, Skil, and BLACK+DECKER print the peak. Same cells, same real voltage, different marketing.
The two honest outliers are Kobalt 24V MAX and Flex 24V. Those packs run six cells in series instead of five, which lands them at 21.6 volts nominal — a real, measurable step up from the 18V-class packs, not a labeling trick. For a train horn it doesn’t change the decibel rating (each horn is engineered and rated for its own platform), but it’s worth knowing if you’re deciding which system to buy into. We put the full head-to-head math in our Milwaukee M18 vs DeWalt 20V MAX battery comparison — spoiler: at equal amp-hours, they tie.
Blasts per charge: amp-hours matter, the logo doesn’t
Because nearly every platform delivers the same 18 volts, runtime comes down to one number printed on the side of your pack: amp-hours. A train horn fires in short one- or two-second bursts rather than the sustained draw of a saw, so capacity converts almost directly into blasts. BossHorn rates its horns at 500+ short blasts — or roughly 200 sustained two-second blasts — on a 6.0Ah pack, and the count scales in a straight line: a 3.0Ah pack gives about half that, a 12.0Ah pack about double.
That linear scaling is the practical answer to “which brand is best for a train horn?” It isn’t the brand — it’s whichever platform you already own the biggest pack for. A Ryobi owner with a 6.0Ah battery gets more horn time than a Milwaukee owner with a 2.0Ah compact, full stop. The horn ships without a battery or charger on the assumption that you already have both, which is the entire point of building on tool platforms instead of a sealed internal battery.
Sound tiers: Dual, Quad, and the Extreme class
The three right-hand columns of the chart are the loudness menu. Dual horns run two trumpets at 130 dB — already far beyond any stock vehicle horn. Quads add two more trumpets and reach 140 dB, the tier available on every platform we build for. The Extreme and Boss Series push past 150 dB with larger trumpets and a higher-output compressor, and they’re currently offered on the nine highest-volume platforms: Milwaukee, DeWalt, Ryobi, Makita, Bosch, Ridgid, Bauer, Hart, and Porter-Cable.
The flagship of that top tier is the Extreme Series Train Horn for Milwaukee® 18v Battery — a 150 dB+ premium quad that snaps onto any M18-compatible pack and fires from a wireless remote, with an optional long-range remote reaching up to 2,000 ft. One caution that applies to every tier: NIOSH warns that a single exposure at or above 120 dB can cause immediate hearing damage, so treat even the “entry” 130 dB Dual with respect and never fire any of these next to an unprotected ear.
Battery brand not on the chart? You still have two routes
If you run a platform we don’t build a dock for — say Metabo HPT or an older Ni-Cd system — the first route is a cross-brand battery adapter: a simple sled that mounts one brand’s pack on another brand’s dock. Adapters work, with caveats around fit, warranty, and low-voltage protection that we cover in detail in our guide to running a train horn on a different brand’s battery with an adapter.
The second route is the DIY Train Horn Gun Kit with Remote — a universal four-trumpet kit rated up to 140 dB that you pair with the battery interface of your choice. It’s the tinkerer’s answer for platforms too niche for a dedicated dock, and it uses the same trumpets and compressor architecture as the pre-built quads.
FAQ
Does a bigger battery make the horn louder?
No. Every pack on a given platform delivers the same nominal voltage whether it’s 2.0Ah or 12.0Ah, and loudness is set by voltage plus the horn’s trumpet and compressor design. A bigger pack only adds more blasts per charge.
Do aftermarket or off-brand batteries work?
Yes. The horn doesn’t talk to the battery’s electronics the way some tools do — any pack that physically mounts the platform’s rail interface and delivers its rated voltage will fire the horn, including aftermarket-compatible packs.
Can I use my DeWalt battery on the Milwaukee version of the horn?
Not directly — every brand uses a proprietary rail and connector, which is exactly why the chart above has 16 separate rows. A cross-brand adapter sled can bridge the gap, or you simply buy the horn version that matches the packs you own.
Which platform should I buy the horn for if I own several?
The one where you own the biggest pack. If you own equal packs on two platforms and one of them is Milwaukee, DeWalt, Ryobi, Makita, Bosch, Ridgid, Bauer, Hart, or Porter-Cable, pick that one — it keeps the 150 dB+ Extreme upgrade path open.