8 min read
Bottom line
The ROLL-ON 3301R is Milwaukee's 7200W starting, 3600W running battery power supply, built on a 6.0kWh integrated REDLITHIUM pack. Zero emissions, quiet operation and an IP54 rating put it inside occupied buildings where a gas generator can't run. It charges to 100% in 8 hours and rolls on 9.5 inch wheels.
What the ROLL-ON 3301R is
ROLL-ON is Milwaukee's wheeled battery power supply, and the 3301R is the 7200W model. It pairs a 6.0kWh REDLITHIUM Integrated battery with an inverter rated at 7200W starting and 3600W running, so it absorbs the surge a motor pulls at startup and then holds a continuous load. Milwaukee states the 6.0kWh pack provides over 2.4X more runtime for long duration operations. The battery isn't removable, so you recharge the machine itself rather than swapping packs.
Two 20A GFCI duplex outlets with circuit breakers handle 120V tool loads, and a USB-C port plus a USB-A port cover phones, layout gear and camera batteries. The inverter runs pure sine wave. Pass-through power lets the unit charge and discharge at the same time, and 9.5 inch all-terrain wheels move it across gravel, dirt and mud instead of stranding it at the curb. Milwaukee backs it with a 3 year limited warranty, and it's in stock at under $9,000.
See DetailsROLL-ON 3301R specs
| Spec | Milwaukee ROLL-ON 3301R |
|---|---|
| Starting power | 7200W |
| Running power | 3600W |
| Battery | 6.0kWh REDLITHIUM Integrated, non-removable |
| Inverter | Pure sine wave |
| Outlets | (2) 20A GFCI duplex with circuit breakers |
| USB | (1) USB-C, (1) USB-A |
| Pass-through power | Yes, charges and discharges at once |
| Ingress protection | IP54 |
| Charge time | 8 hours to 100%, under 100 minutes to 25% |
| Wheels | 9.5 in all-terrain |
| Storage | Modular connectivity with PACKOUT components |
| ONE-KEY | Tracking, management and adjustable charging rate |
| Shipping weight | 195 lb |
| Warranty | 3 Year Limited |
| In the box | Power supply and charging cord |
Pure sine wave, pass-through power and IP54, in plain terms
Three lines on the spec sheet carry more weight on site than they look. Here's what each one means for the work in front of you.
- Pure sine wave: the AC output follows the same smooth waveform a utility outlet delivers. Battery chargers, laser levels, test instruments and anything with a motor speed controller behave the way their makers assumed, without the extra heat and buzz a chopped waveform can produce.
- Pass-through power: the unit takes a charge and feeds its outlets at the same time. Plug it into building power or a temporary feed and it keeps supplying tools while it refills, so it works as a buffer rather than a bucket you drain and haul away.
- IP54: an ingress protection rating, read as two digits. The 5 means dust protected. The 4 means protected against splashing water from any direction. That's the basis for the indoor and temporary outdoor use Milwaukee describes, not permission to leave it in standing rain.
- 20A GFCI duplex with circuit breakers: ground fault protection sits in the outlet itself, so you're not chasing a GFCI pigtail or a cord end, and an overload trips a breaker you reset by hand.
ROLL-ON 3301R vs a gas generator
The case for a battery power supply gets clear on inspections-heavy interior work: hospitals, schools, occupied offices, tenant fit-outs. A gas generator has to sit outside, away from doors and windows, with a cord run back into the building. ROLL-ON carries no exhaust and no fuel, so the power source stays in the room with the crew and the cord run gets short.
| Consideration | ROLL-ON 3301R | Gas generator |
|---|---|---|
| Emissions | Zero emissions | Combustion exhaust, including carbon monoxide |
| Noise | Quiet operation | Engine noise the whole time it runs |
| Indoor work | IP54, rated for indoor and temporary outdoor use | Outdoors only, away from doors, windows and vents |
| Fuel on site | None. It recharges from an outlet | Gasoline to buy, haul and store |
| Routine service | No oil, filters or spark plugs | Oil changes, filters, plugs and fuel system service |
| Refill model | 8 hours to 100%, under 100 minutes to 25% | Refuel whenever the tank runs down |
| Output waveform | Pure sine wave | Varies by model |
| Start of shift | Instant setup, nothing to warm up | Start the engine and let it settle |
The honest trade is the refill model. A gas unit takes minutes and a can of fuel to keep going, while ROLL-ON takes 8 hours to reach 100% and under 100 minutes to reach 25%. That's a scheduling question rather than a performance one. Crews charge overnight, and pass-through power keeps the unit live through the day wherever building power is already available.
- Best for Occupied interiors and inspections-heavy work: Milwaukee ROLL-ON 3301R Zero emissions and quiet operation keep the power source in the room instead of outside on a long cord run.
- Best for Sensitive electronics, instruments and chargers: Milwaukee ROLL-ON 3301R Pure sine wave output matches what those devices expect from a wall outlet.
- Best for Gravel, dirt and mud between the truck and the work: Milwaukee ROLL-ON 3301R 9.5 inch all-terrain wheels and PACKOUT connectivity move power and boxes in one trip.
- Best for Crews already running ONE-KEY: Milwaukee ROLL-ON 3301R Integrated ONE-KEY adds inventory tracking plus an adjustable charging rate.
Charging, ONE-KEY and the end of the shift
Charge time is 8 hours to a full 6.0kWh pack and under 100 minutes to 25%, from the charging cord in the box. ONE-KEY is integrated, which covers tracking and tool management plus an adjustable charging rate, so you can hold back the draw when the circuit you're plugged into has other work to do. The unit also carries modular connectivity with PACKOUT components, so boxes ride in with the power instead of costing a second trip.
Where it fits next to Milwaukee's other power gear
If you're comparing the full range, our guide to Milwaukee power stations and generators lays the options out by size and duty. For lighter interior work where a rolling unit is more machine than the task needs, the M18 Power Supply covers a smaller footprint on batteries you already own. And if the reason a generator lives on your truck is the equipment it feeds, the MX FUEL guide shows which of those machines already run without one.
Key Takeaways
- 7200W starting and 3600W running from a 6.0kWh REDLITHIUM Integrated battery, which Milwaukee credits with over 2.4X more runtime.
- Two 20A GFCI duplex outlets with circuit breakers, one USB-C port and one USB-A port.
- Pure sine wave output, pass-through charging, and an IP54 rating for indoor and temporary outdoor use.
- 8 hours to 100% and under 100 minutes to 25%, from the included charging cord.
- 9.5 inch all-terrain wheels, PACKOUT modular connectivity, integrated ONE-KEY, 3 year limited warranty.
Can the ROLL-ON 3301R run indoors?
Yes. Milwaukee states zero emissions, quiet operation and an IP54 rating, and describes the unit as supporting indoor and temporary outdoor use. There's no exhaust to route and no fuel to store, so it works in the space with the crew instead of sitting outside on a cord run. Read IP54 as splash protection, not as a rain rating.
Is the battery removable?
No. The 6.0kWh REDLITHIUM battery is integrated, so you recharge the unit rather than swapping packs. Milwaukee states the pack provides over 2.4X more runtime for long duration operations. Pass-through power covers the gap a fixed battery creates: plug the unit into building power and it keeps feeding its outlets while it charges.
How long does the ROLL-ON take to charge?
8 hours to 100%, and under 100 minutes to 25%, using the charging cord that ships with it. Overnight is the normal pattern for a full pack. The 25% figure is the one that matters at lunch or between phases, since a partial charge puts usable energy back without holding up the crew.
What's the difference between 7200W and 3600W?
7200W is starting power, the brief surge an inductive load pulls as a motor spins up. 3600W is running power, the continuous output the unit sustains. Size your loads against the 3600W figure and treat 7200W as headroom for startup rather than a level you hold.
Does the 3301R work with PACKOUT?
Yes. Milwaukee lists modular connectivity with PACKOUT components, so boxes attach and travel with the unit on its 9.5 inch all-terrain wheels. That pays off on a long walk from the truck across gravel or dirt, where a second trip for tool boxes costs more time than the power hookup itself.
What does ONE-KEY do on this unit?
ONE-KEY is integrated for tracking and management, and on the ROLL-ON it also sets an adjustable charging rate. That lets you cap how hard the power supply pulls while charging, which helps when it shares a circuit with other loads. Tracking is the other half, so the unit reports in alongside the rest of your inventory.
What warranty comes with the ROLL-ON 3301R?
A 3 year limited warranty. The box holds the power supply and a charging cord, so there's no separate battery or charger term to track, which is one side effect of the integrated pack. Register the unit in ONE-KEY when it lands so it's on your inventory from the first day.
Does it replace a gas generator outright?
For interior and inspections-heavy work it removes the reasons a generator stays outside: exhaust, fuel storage and engine noise. The difference is the refill model, since recharging takes hours where refueling takes minutes. Crews that charge overnight and use pass-through power during the day rarely feel that gap.
Is the 3301R in stock?
It's listed in stock, and it ships with the power supply and a charging cord. Store pricing sits under $9,000. Availability on new Pipeline gear shifts as orders land, so check the product page before you plan around a delivery date.