How many watts does a power tool battery charger use?
A power tool battery charger draws 85–230 watts while running, which is 0.71–1.9 amps on a 120 V circuit.
Power tool battery charger watts, amps and circuit
| Running watts | 85–230 W |
|---|---|
| Voltage | 120 V |
| Running amps | 0.71–1.9 A |
| Circuit | standard 120 V outlet |
Also called: milwaukee charger, milwaukee m18 charger, dewalt battery charger, tool battery charger.
Power tool battery charger watts by size and type
| Size or type | Running watts, W | Volts, V | Amps, A | Starting watts, W |
|---|---|---|---|---|
| Power tool battery charger | 85–230 | 120 | 0.71–1.9 | — |
| Standard 18 V charger | 85 | 120 | 0.71 | — |
| Rapid or dual-platform charger | 120–230 | 120 | 1–1.9 | — |
What size generator runs a power tool battery charger?
A power tool battery charger needs a generator that supplies at least 230 running watts. A 2,000 W generator covers it with its running rating alone; add the watts of anything else you run at the same time.
How long a portable power station runs a power tool battery charger
| Battery capacity, Wh | At 230 W, h | At 85 W, h |
|---|---|---|
| 500 | 1.8 | 5 |
| 1,000 | 3.7 | 10 |
| 2,000 | 7.4 | 20 |
| 3,600 | 13.3 | 36 |
A 500 Wh portable power station runs a power tool battery charger drawing 230 W for about 1.8 hours at 85% inverter efficiency. Runtime = capacity × 85% ÷ watts; the 85% efficiency is an assumption. The power station's AC output must be at least 230 W.
What it costs to run a power tool battery charger
Running a power tool battery charger at 158 W, the middle of its 85–230 W range, for one hour a day uses 57.7 kWh a year. That costs about $10 a year at $0.18 per kWh, the US average residential price for August 2026.
Your bill's total ÷ kWh used. 0.18 is the US residential average.
- Per day
- $0.03
- Per year
- $10
- Energy per day
- 0.16 kWh
- Energy per month
- 4.8 kWh
How it is calculated
- kWh per day = 158 W × 1 h ÷ 1,000 = 0.158
- Per month = 0.158 kWh × 30.4 days × $0.18 = $0.87
What affects power tool battery charger power use
A charger draws its rated power while it fills a low battery and less as the battery nears full. Rapid chargers fill packs faster by drawing more. The watts are the input ratings Ryobi lists; Milwaukee lists input current instead, up to 2.75 A at 120 V for its M18 and M12 Rapid Charger.
How the amps are calculated
Amps = watts ÷ volts. For 230 W at 120 V that is 1.9 A. The 85–230 W range covers typical models; the nameplate on a power tool battery charger gives the exact figure.