7kW vs 22kW EV Charger for Single-Phase Australian Homes
Why 22kW chargers drop to 7.4kW on 90% of Australian homes, how to check your switchboard, and when a 3-phase upgrade is actually worth the cost.
Key Takeaway for Australian Homeowners
If your home has a single-phase electrical supply (like 90% of Australian residential properties), your maximum AC charging speed is 7.4kW (32 Amps at 230V). Buying a 22kW charger will not charge your car any faster on single-phase power — it will automatically operate at 7.4kW.
1. The Math: Why Single-Phase Caps Out at 7.4kW
Australian single-phase household circuits operate at a nominal 230 Volts. The standard maximum continuous current allowed for a single EV dedicated circuit is 32 Amps.
A 22kW charger requires three separate 230V active lines (3-phase) drawing 32 Amps each (230V × 32A × 3 = 22.08kW). If you plug a 22kW charger into a single-phase supply, it can only use one line, capping output at 7.4kW.
2. Charge Time Comparison (7.4kW vs 11kW vs 22kW)
Charge times from 10% to 80% state of charge (typical daily charging range):
| EV Battery Capacity | 7.4kW (Single-Phase) | 11kW (3-Phase AC) | 22kW (3-Phase AC) |
|---|---|---|---|
| 57.5 kWh (Tesla Model 3 RWD) | 5.4 hours | 3.6 hours | 3.6 hours (capped by 11kW car limit) |
| 60 kWh (BYD Atto 3 Extended) | 5.6 hours | 5.6 hours (7kW car limit) | 5.6 hours (7kW car limit) |
| 77.4 kWh (Kia EV6 / Ioniq 5) | 7.3 hours | 4.9 hours | 4.9 hours (11kW car limit) |
| 105.7 kWh (BMW i7) | 10.0 hours | 6.7 hours | 6.7 hours (11kW car limit) |
Note: Almost all modern EVs sold in Australia have onboard AC chargers capped at either 7kW or 11kW. Very few passenger EVs (e.g. older Renault Zoe or Porsche Taycan with 22kW option) can accept 22kW AC.
3. Should You Upgrade Your Home to 3-Phase?
Stick with 7.4kW Single-Phase if:
- • You drive under 150 km per day.
- • You park and charge overnight (8+ hours available).
- • Your vehicle has an onboard AC limit of 7kW to 11kW.
- • You want to avoid potentially expensive electrical supply upgrade costs.
Consider 3-Phase Upgrade if:
- • You own 2 or more EVs needing simultaneous fast charging.
- • You drive 200+ km daily and have short turnaround times between trips.
- • You have a large rooftop solar array (10kW+) and want to soak up 11kW–22kW of solar surplus.
Frequently Asked Questions
Can I buy a 22kW charger now for future-proofing?
Yes! Models specified as single_and_three (e.g. Wallbox Pulsar Max, Sungrow AC22E-01, SolaX G2) can be installed on single-phase power now at 7.4kW, and re-wired for 22kW if you ever upgrade your switchboard to 3-phase later.
What happens if I install a three-phase ONLY charger on single-phase?
Chargers rated strictly as three-phase only (with no single-phase wiring mode) will either fail to operate or cap output at ~7.4kW or less. Always verify phase_support on our charger detail pages.
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