A Complete Sizing Guide for Every Trade Tool — From Drills to Tower Cranes
You've seen the specs. You know a battery power station can replace a diesel generator on your job site. But the question every contractor asks before buying is simple: what tools can it actually run?
The answer isn't just about watts. It's about understanding the difference between running power and surge power — and matching your tools to the right system. This guide breaks down exactly what Purmars battery power stations can handle, from a cordless drill charger to a 15kW tower crane auxiliary load.
Running Watts vs. Surge Watts: Why This Matters More Than You Think
Before you check any compatibility table, you need to understand two numbers that appear on every tool:
Running watts (continuous power) — the power a tool draws during normal operation. A 7¼" circular saw might run at 1,800W.
Surge watts (starting/peak power) — the brief spike of power a motor draws at startup to overcome inertia. That same circular saw can spike to 3,600W or more in the first 200–300 milliseconds.
Here's the problem. A power station rated at 2,000W continuous can run a 1,800W saw — but if its surge capacity is only 2,500W, the inverter will trip the moment you pull the trigger. The motor never gets the punch it needs to start.
Motor-driven tools (saws, drills, grinders, pumps) typically need 2 to 3 times their running watts to start. Compressors — those pancake units you wheel around for pneumatic nailers — can surge to 5 times their running watts. A 1,200W pancake compressor that feels modest on paper may demand 6,800W at startup.
This is the single most important number when sizing a power station. Not the continuous watts. The surge watts.
Tool-by-Tool Power Requirements: What Runs on What
The table below pairs real tool loads with the Purmars model that handles them comfortably — with surge headroom included.
Tool Type | Typical Running Power | Startup Surge | Recommended Purmars Model |
LED lighting arrays | 200–500W | None | EP3000 / EP6000 |
Drill / angle grinder | 800–1,500W | 2–3× running | EP3000 / EP6000 |
Small welder | 2,000–3,500W | 4,000–6,000W | EP8000 / AP18 |
Medium welder | 5,000–8,000W | 10,000–15,000W | AP30 |
Small air compressor | 1,500–2,500W | 4,500–7,500W | EP8000 |
Concrete vibrator | 1,000–2,000W | 3,000–5,000W | EP6000 / EP8000 |
Water pump | 1,000–1,500W | 2,500–3,500W | EP6000 / EP8000 |
Cut-off saw / table saw | 1,500–3,000W | 4,500–8,000W | EP8000 / AP18 |
Tower crane (auxiliary) | 5,000–15,000W | 15,000–30,000W | AP30 |
A quick reality check: the EP3000 delivers 3,000W continuous output and 2,560Wh capacity. That's enough to run a drill, an angle grinder, LED work lights, and a charger bank simultaneously — all the light-duty loads a service call or renovation crew needs.
The EP6000 pushes that to 5,500W continuous and 5,120Wh. Now you're running a small welder, a concrete vibrator, and site lighting together without breaking a sweat.
The EP8000 brings 5,000W continuous and a 15,000W peak — the surge headroom to start compressors, cut-off saws, and small welders that would trip lesser systems.
And the AP30/AP42 series? That's three-phase territory. 30kW to 42kWh, built for tower crane auxiliary power, large welders, and multi-tool industrial sites.
What Happens When You Run Multiple Tools at Once
Here's where most contractors get caught. You don't run one tool at a time on a real job site. You run three.
The calculation is straightforward — but easy to get wrong:
Total continuous load = Tool A running watts + Tool B running watts + Tool C running watts
Peak demand =Total continuous load + (Highest single surge − That tool's running watts)
Example: You're running a cut-off saw (2,000W), an angle grinder (1,200W), and two LED light arrays (400W total). That's 3,600W continuous. The cut-off saw surges to 5,000W at startup. Your peak demand is 3,600W + 3,000W = 6,600W.
The EP6000 (5,500W continuous) would struggle here. The EP8000 (5,000W continuous, 15,000W peak) handles it — but only if the saw starts first and the grinder and lights come on after.
The practical solution: stagger your startups. Turn on the biggest surge load first, let it stabilize, then bring the rest online. This simple habit can let you size down from a larger system — saving thousands in equipment cost.
Matching Purmars Models to Real Job Sites
Different sites need different systems. Here's how the Purmars lineup maps to actual scenarios:
Service calls and light renovation → EP3000
Running a drill, a grinder, and LED lighting in an occupied building? The EP3000 handles it at 3kW continuous, rolls in on its handle, and produces zero noise. No fumes in the hallway. No extension cord to the far end of the floor.
Active construction and roadwork → EP6000
This is the workhorse. 5.5kW continuous covers circular saws, drills, concrete vibrators, and site lighting simultaneously. Optional MPPT solar input means you can recharge from panels on remote sites. The 5,120Wh capacity supports roughly 8 hours of moderate load — a full shift.
Heavy tools and compressor loads → EP8000
When you need to start a 1,200W compressor that surges to 6,800W, the EP8000's 15kW peak is the difference between working and waiting. Built with semi-solid-state LiFePO₄ cells that pass puncture safety testing, it's designed for the abuse a real job site delivers.
Three-phase industrial applications → AP18 / AP30
Tower cranes, large welders, multi-tool operations — these need three-phase power and serious capacity. The AP30 delivers 30kW and 42kWh across seven battery packs with integrated fire suppression. It's the heavy end of silent site power.
Pro Tips: Reading Tool Nameplates and Managing Peak Demand
How to read a tool's power rating
Check the nameplate for watts (W) or amps (A). If only amps are listed, multiply by voltage (230V in Europe, 120V in North America). A tool rated at 15A at 120V draws 1,800W running. But that's just the beginning — assume 3× surge for motor loads and 5× for compressors.
The stagger technique
Never start all your high-surge tools at once. Sequence them: compressor first, then saw, then lights and chargers. This keeps your peak demand manageable and your inverter happy.
Add a 20% safety margin
Real-world conditions — cold motors, voltage sag, extension cord losses — eat into performance. If your calculated peak is 6,000W, choose a system that delivers 7,200W peak or more.
The Bottom Line
A battery power station can run almost any corded tool on a modern construction site — if you match the surge capacity to your actual loads. The EP3000 covers light trades. The EP6000 covers active construction. The EP8000 handles heavy tools and compressors. And the AP series powers the three-phase equipment that used to be diesel-only territory.
The question isn't whether battery power works on a job site. It's which Purmars system fits your crew's tool list.
Ready to size your system? Download the complete tool power compatibility chart or contact our team for a free site load assessment.
Purmars — Construction-Grade Battery Storage. Built for the job site. Engineered to last. OEM/ODM partnerships available worldwide.
