Short answer: yes. If you already own a Ryobi ONE+ 18V battery, you can run a portable train horn gun off the exact same pack you use for your drill, blower, or string trimmer — no wiring, no air tank, no separate charger. Here's exactly how the fit works, which batteries to use, and what kind of blast to expect.
The short answer: Ryobi ONE+ is fully supported
A train horn gun is a handheld, drill-style horn that snaps onto a power-tool battery and uses that battery to drive a small onboard air compressor. Pull the trigger (or hit the wireless remote) and the compressor pushes air through metal trumpets to produce a real locomotive blast. Because the Ryobi ONE+ system is one of the brands we build around, a Ryobi-specific horn gun accepts your ONE+ packs directly — there's no adapter and no modification needed.
That makes Ryobi one of the easiest battery platforms to add a horn to. If your garage already has a couple of ONE+ batteries on the shelf, the only thing you're buying is the horn itself.
Why Ryobi ONE+ is such an easy match
Ryobi launched the ONE+ platform in 1996 and has kept one promise ever since: every 18V ONE+ battery fits and powers every ONE+ tool, and every ONE+ charger charges every ONE+ battery. There's no firmware lockout and no generation limit — a pack you bought last year works in a tool from 2004, and a first-generation NiCd pack still physically fits the newest lithium tools.
That same slide-on connector is what a Ryobi horn gun uses. The system now powers well over 300 tools, which is a big reason ONE+ has the largest consumer cordless install base in the U.S. — odds are good you, or someone in your driveway, already has the battery.
Which Ryobi batteries work — and how long they last
Any genuine 18V ONE+ battery will run the horn. The only practical difference between packs is amp-hours (Ah), which determines how many blasts you get per charge. Higher Ah means more air and more honks before a recharge. Battery life scales with capacity — a typical 5Ah-class pack is good for roughly 1,500+ blasts on a single charge, and larger packs go longer.
| Ryobi ONE+ pack | Capacity | Best for |
|---|---|---|
| P102 (compact) | 1.5 Ah | Lightest setup; fewest blasts — fine for occasional use |
| P107 / P108 | 2.0–4.0 Ah | Best all-around balance of weight and runtime |
| P194 / HP packs | 6.0 Ah | Long sessions — tailgates, events, off-road days |
| 9.0 Ah HIGH PERFORMANCE | 9.0 Ah | Maximum runtime; heaviest pack |
Ryobi sells two tiers: standard packs and HIGH PERFORMANCE (HP) packs. Both work in the horn gun. The HP packs deliver their full boosted output in HP-branded tools, but in a horn they simply act as a bigger fuel tank — more capacity, more blasts. There's no wrong choice; pick based on how long you want to go between charges.
‘18V’ vs ‘20V MAX’ — clearing up the voltage confusion
People sometimes worry their Ryobi pack is “weaker” than a DeWalt because Ryobi says 18V and DeWalt says 20V MAX. It's the same battery. A so-called 20V MAX pack peaks at 20 volts off the charger and settles to 18 volts nominal under load — which is exactly what Ryobi labels its packs to begin with. The difference is marketing, not power. A Ryobi ONE+ pack delivers the voltage a horn gun needs, full stop.
The thing that actually matters for a portable horn isn't a couple of volts — it's amp-hours and the brand of the connector. Match the connector (buy the Ryobi version of the horn) and choose your Ah for runtime, and you're done.
How the horn gun uses your Ryobi battery
There's no air tank and no compressor box bolted under your hood. The horn gun houses a small electric air pump in the body of the tool. The Ryobi battery powers that pump; the pump pressurizes air on demand; the air exits through powder-coated metal trumpets. That's the whole system, and it's why the unit is genuinely portable — you can carry it from the truck to the boat to the campsite and just swap the battery you already own.
That portability is the real advantage of a battery-platform horn over a permanently mounted tank kit. There's nothing to wire into your truck's electrical system, nothing to drill through the firewall, and nothing that has to come off before a state inspection. When you're done, the horn goes back in the cab or the toolbox alongside your other Ryobi gear. For boaters, RV travelers, and off-road riders who move between vehicles, that means one horn covers all of them.
Our Ryobi model uses four metal trumpets and is rated up to 150 dB, with a wireless remote that triggers it from up to 160 feet away. Because it's not permanently wired to a vehicle, you can keep it in the cab and pull it out only when you need it.
Want it louder? Step up to a 5-trumpet
The Ryobi quad is plenty for most trucks, UTVs, and boats. If you want the biggest possible blast and you happen to run Milwaukee batteries, the 5-Trumpet Horn Gun for Milwaukee® 18V Battery adds a fifth trumpet for a fuller, deeper chord. The trumpet count drives the tone and presence; the battery brand just decides which pack snaps on. Pick the horn that matches the batteries already in your garage.
What's included
- The horn gun — four metal trumpets and the onboard air pump in a Ryobi-compatible body.
- Wireless remote — triggers the horn from up to 160 ft on the standard package.
- Battery options — buy the horn alone if you already own ONE+ packs, or add a battery (and charger) at checkout if you're starting fresh.
Note the battery is not bundled by default, precisely because most Ryobi owners already have one. That's the whole point of a battery-platform horn: you reuse what you've got.
FAQ
Do I need a special Ryobi battery for the horn?
No. Any genuine 18V ONE+ pack works — compact 1.5Ah, mid-size 4Ah, or a 6Ah/9Ah HIGH PERFORMANCE pack. Higher amp-hours just means more blasts between charges.
Will an old NiCd Ryobi battery still work?
Physically, yes — ONE+ has kept the same battery interface since 1996, so even first-generation packs fit. For the best runtime and consistent pressure, a modern lithium pack is the better choice.
How many honks do I get per charge?
It depends on the pack. A 5Ah-class battery is good for roughly 1,500+ blasts; smaller packs give fewer, larger packs give more. For all-day events, carry a spare battery and swap it like you would on any other ONE+ tool.
Can I use the same battery in my drill and the horn?
Yes — that's the entire idea. The horn draws from the same ONE+ pack your other tools use, so one set of batteries covers everything.
Is it as loud as a Milwaukee or DeWalt version?
The loudness comes from the trumpets and air pump, not the battery brand. A Ryobi quad and a DeWalt quad with the same trumpet count put out the same blast. Trumpet count — dual, quad, or 5-trumpet — is what changes the volume and tone.