Cordless Tool Charging From a Power Station: Smart Backup, Tiny Bill Savings

A cordless-tool charger is a tiny load compared with an EV or microwave, but it is a great example of when a power station is useful without pretending it will slash your electric bill.

If you already own a portable power station, it can charge drill, impact-driver, flashlight, radio, or lawn-tool batteries in the garage, on a jobsite, at camp, or during an outage. The question is not just “Can it do it?” It is also “How much energy does it actually use, and does shifting that load save meaningful money?”

Think of it like filling a small gas can

A tool-battery charger is like filling a small gas can from a much larger tank. The power station has plenty of capacity for the job, but the amount of energy moved is small. That is why the convenience can be valuable even when the dollar savings are modest.

Simple electricity diagram

LOW-COST / SOLAR CHARGE PERIOD

[Grid or Solar]
      │
      ▼
[Power Station Battery]
      │
      ▼
      AC
      │
      ▼
[Tool Battery Charger]
      │
      ▼
[Drill / Impact Battery]

A realistic charging example

Suppose your charger draws 120 watts while charging and runs for 55 minutes.

Energy used:
120 W × 0.92 hours ≈ 110 Wh, or 0.11 kWh.

A power station with more than 120 W of continuous AC output can support that worked-example load. Most modern power stations exceed that by a wide margin, but always check the charger's input label and the power station's continuous-output rating. Do not assume every charger draws 120 W; this is an example for the math.

Does shifting that charge save money?

Sometimes, but not much for a load this small.

Southern California Edison's current TOU-D-5-8PM winter schedule lists roughly 32¢/kWh from 8 a.m.–5 p.m. and 55¢/kWh from 5–8 p.m. before the baseline credit. Rates vary by plan and provider.

If we use an illustrative 85% round-trip battery efficiency, delivering 0.11 kWh later requires about:

0.11 ÷ 0.85 ≈ 0.129 kWh of earlier charging energy.

Charging the power station at 32¢/kWh costs about 4.1¢ for that energy. Running the 0.11 kWh charger directly during the 55¢/kWh period costs about 6.1¢.

Estimated savings: about 2¢ per charging session.

That means peak shifting a single tool charger usually does not justify buying a power station by itself. The economics improve when the station is already owned, charged from otherwise-unused solar, or used to shift several household loads together.

Tonight's Power Station Use

If you are already charging your power station during a lower-cost period, use it tonight to top off a drill battery, flashlight battery, laptop, phone, or Wi-Fi backup battery while leaving the grid load off during the expensive window.

For a family or renter, a better money-saving strategy is often to combine small loads: TV, Wi-Fi, lights, laptops, game consoles, and chargers. The combined energy use is large enough to make rate shifting more noticeable than one tool charger alone.

Where this really helps

Home garage: Charge tools without running an extension cord across the driveway.

Jobsite: Keep cordless batteries moving when permanent power is not available.

Camping: Recharge tools, lights, and electronics from one portable source.

Outage: Keep essential cordless tools and work lights ready without starting a generator for a small load.

Safety first

Use the tool manufacturer's charger and follow its input requirements. Keep the power station and charger dry and ventilated. Do not bypass breakers, GFCI protection, grounding, battery-management protections, or charging interlocks. Never backfeed a home or jobsite electrical system.

Bottom line: Charging cordless tools from a power station is excellent for convenience and resilience. For electricity-bill savings, the math says one small charger saves only pennies per session—so combine loads or use solar if your goal is meaningful savings.

EcoFlow offer

New eligible users can join through the GreenStone Guard EcoFlow referral link and may receive a 5% off coupon on selected EcoFlow products: EcoFlow Referral Rewards.

Referral disclosure: GreenStone Guard may receive a referral benefit from qualifying activity. EcoFlow controls eligibility, exclusions, selected products, and current program terms.

Sources: Southern California Edison, Time-of-Use residential rate information; National Renewable Energy Laboratory 2024 Annual Technology Baseline, residential battery storage; EcoFlow U.S. referral-program terms.

Featured photo: Marcelo Verfe / Pexels, free to use.