Most crews today carry cordless tools, and the batteries that run them can do more than spin a drill. A cordless power adapter, often called a battery inverter, mounts directly onto a tool battery and converts its stored DC power into 120V AC current plus USB output for charging phones and tablets. Cordless power tool battery systems power modern construction work in more ways every year, and inverters are among the newest additions. A compact model such as the Craftsman CMCB1150B delivers up to 150W of AC power, adds a USB-C and a USB-A port, includes an LED worklight, and sells for about $49 as a tool-only purchase.
How Cordless Power Adapters Work
An inverter adapter does three jobs in one housing. It holds the battery, converts DC to AC, and provides USB ports for electronics. The battery slides into the base, the inverter electronics sit in the middle, and the outlets face outward for easy access. Because the battery is the power source, the adapter works anywhere a charged pack fits, with no extension cord and no generator.
Conversion starts with the battery’s DC voltage. A 20V-class battery outputs roughly 18 to 20V depending on charge state. Inverter circuitry steps that up to 120V AC at 60Hz, the standard for household current. The process is not free: typical inverters lose 10 to 15 percent of the energy as heat, which matters when you calculate runtime.
From Battery Voltage to Household Current
Voltage platforms differ between brands, but the principle is the same. A 20V platform, an 18V platform, and a 36V or 40V platform all feed inverter circuits that produce the same 120V AC output. The difference shows up in capacity and current draw, not in the outlet voltage. The voltage platforms and cell configurations decide how much energy the pack holds and how fast it can deliver it, which is exactly what determines how long an adapter runs.
What 150 Watts Actually Means
A 150W rating describes continuous output. The AC outlet delivers 150W at about 1.25A, since 150 divided by 120 equals 1.25. That is enough for a work radio, an LED worklight, a laptop charger under 150W, or a small fan. It is not enough for a circular saw, a heater, or a kettle, which typically draw 600W to 1,500W. Matching the load to the rating is the most important step in using an adapter safely.
The adapter can also run multiple outputs at once. Product images show a phone, a tablet, and another device connected at the same time, which means the AC outlet and the USB ports share the total power budget. A 60W load on AC leaves roughly 90W of headroom for USB devices.
Key Outputs and What They Can Power
Before buying any inverter adapter, compare the outputs against the devices you actually carry. The table below shows the three output paths on a typical compact adapter and the equipment each one can handle.
| Output | Rating | What it can power |
|---|---|---|
| 120V AC | 150W, about 1.25A | Work radios, LED worklights, fans, laptop chargers up to 150W |
| USB-A | 5V at 2.4A, 12W | Phones, earbuds, GPS units, small lights |
| USB-C | 5V at 3.0A, 15W | Phones, tablets, power banks, devices under 15W |
The USB-C port on many of these adapters supports only the 5V profile, not Power Delivery. A phone that charges at 18W or 25W from a wall charger falls back to a slower 15W or less from the adapter. Apple users can still pair a USB-C to Lightning cable for faster charging than an older USB-A cable, but a modern phone expecting 45W will not see those speeds. If you need Power Delivery, check the spec sheet before buying.
The same battery platform powers a whole family of tools, and that ecosystem is much of the value. The V20 line spans drills, drivers, saws, vacuums, and the cordless power cleaner review published by Pro Tool Reviews. An inverter adapter slots into that lineup as the piece that turns stored battery energy into household-style power.
USB Charging on the Jobsite
Phones and tablets have become essential on construction sites. Crews use them for plans, measurements, photos, time tracking, and calls, and a dead phone can stop work. A battery adapter turns a tool battery into a phone charger that works in a trench, on a roof, or inside an unfinished wall, anywhere a wall outlet is out of reach.
- USB-C at 15W charges most modern phones from empty to about 50 percent in roughly an hour.
- USB-A at 12W is slower but still useful for earbuds, flashlights, and older devices.
- Both ports can run at the same time, so two people can charge two phones from one battery.
- The LED worklight on some adapters doubles as a task light for small jobs.
Charging Speeds Compared
Charge speed matters on a deadline. A 5W charger adds about 5 percent per 20 minutes to a typical 4,000mAh phone battery. A 12W USB-A port roughly doubles that, and a 15W USB-C port adds about 12 to 15 percent in the same window. None of these match a 25W or 65W wall charger, but they beat a dead battery.
Cables and Batteries Affect Real Speed
Cable quality changes real-world results. Thin, worn cables drop voltage and slow charging noticeably. Keep one good USB-C cable rated for at least 3A in the tool bag. Battery size matters too: a 2Ah pack holds about 40Wh, which is roughly three full phone charges. A 5Ah pack holds 100Wh and covers a full day of device charging for a small crew.
Larger options exist for bigger needs. Portable power stations are changing cordless jobsite power supply by packing hundreds of watt-hours into wheeled boxes, and a station can run a laptop for hours or power a small fridge. A battery adapter is the lightweight version of that idea: less capacity, far less weight, and no separate unit to charge.
Matching an Adapter to Your Battery Platform
An inverter adapter is platform-locked. A V20 adapter only takes V20 batteries, and an 18V adapter only takes that brand’s packs. That is actually a strength: the adapter inherits the batteries, chargers, and storage you already own. Before buying, confirm the adapter matches the battery family you carry, then think about capacity.
- Check the minimum and maximum battery size the adapter accepts. Some units refuse small packs or sag under load with a 1.5Ah battery.
- Look for a battery gauge. The best adapters show remaining charge, so you know when to swap packs.
- Tool-only pricing assumes you already own batteries. Starting from zero, a kit with a battery and charger changes the math.
- Weight matters when the adapter hangs off a belt or sits on a bench. A 2Ah pack plus a compact adapter stays light; a 5Ah pack adds heft but doubles runtime.
Tool-Only vs Kit Pricing
The $49 price for the adapter alone is typical of tool-only offerings. Manufacturers price accessories low because they expect you to own the platform. If you are already invested in a battery system, tool-only pricing is the cheapest way to add AC power. If you are not, the cost of batteries and a charger can exceed the adapter itself.
Storage and Mounting Options
Portable power is only useful if you can find it. Many adapters include mounting and storage features: a rubber overmold for grip, an integrated worklight, and a screw hole backed by a nut that accepts a belt hook or a wall-track hook. Some brands call this Versatrack compatibility, which is simply a standardized mounting hole. A hook lets you hang the adapter on a pegboard or wall rail at the workbench so it is ready when needed.
Compact tools follow the same logic of size versus power. Compact cordless power tools in construction balance brushless motors, battery size, and performance, and an adapter is a compact power device of a different kind: small, battery-driven, and built around the limits of what a handheld pack can deliver.
Practical Limits and Safe Usage
An inverter does not create power; it converts what the battery holds. Runtime falls fast at high loads, and some devices should never be plugged into a 150W adapter. Understanding both facts prevents dead batteries and damaged equipment.
Estimating Runtime
Runtime is simple arithmetic. Multiply battery capacity in amp-hours by nominal voltage to get watt-hours. A 2Ah, 20V pack holds 40Wh. Divide by the load: at 150W, 40 divided by 150 is about 16 minutes, and inverter losses cut that to roughly 13 or 14 minutes. At a realistic 30W load, the same battery lasts more than an hour. A 5Ah pack holds 100Wh and runs a 15W phone charger for more than six hours.
- Full-load AC draw drains a 2Ah pack in about 15 minutes.
- Mixed use, like a radio plus phone charging, typically runs between 30 and 60 percent load and lasts much longer.
- Keep a second battery charged if the adapter will drive any real AC load.
What Not to Plug In
High-draw tools are off the list. Saws, grinders, band saws, and cut-off saws can pull 1,000W or more at startup, far beyond a 150W inverter. Those tools belong on their own batteries. Cordless power tool categories such as band saws, cut-off saws, and other jobsite power options exist precisely because corded-class power needs dedicated packs. Heaters, kettles, and hair dryers also exceed the rating. When in doubt, check the device label: if it asks for more watts than the adapter provides, use another power source.
Keep the adapter dry and ventilated. Inverter electronics generate heat under load, and the housing vents need airflow. Do not stack rags or materials on top of a running adapter, and do not use it in standing water. The rubber overmold protects against bumps, not immersion.
Choosing the Right Cordless Power Solution
The decision is not adapter versus nothing; it is adapter versus the other ways to get power on site. Match the solution to the load, the duration, and how much you want to carry.
- A battery inverter is the best fit for phone charging, radios, lights, and short bursts of small AC loads.
- A portable power station wins when you need hours of laptop power or a crew-wide charging hub.
- A generator makes sense for heavy loads or all-day use, at the cost of fuel, noise, and maintenance.
- Extra batteries alone solve the phone problem only if you already own a USB adapter.
Budget matters at the end. The adapter’s $49 price looks different once you add the batteries it needs. Choosing a cordless power tool combo kit with batteries and value pricing can change what an upgrade costs. Start with the battery family you own, match the adapter to the devices you carry, and the choice becomes straightforward.