7kW vs 22kW Home EV Charger: Which Do You Actually Need?
The instinct is reasonable: more kilowatts, faster charging, buy the bigger one. But EV charging has a bottleneck most buyers don’t find out about until after the money’s spent — and it isn’t the wallbox on your wall.
The thing that actually decides your charging speed
Every EV has an onboard charger built into the car. Its job is converting the AC power from your wall unit into the DC your battery accepts. That component has a fixed maximum rating, and it caps your charging speed no matter what you plug into.
Plug a car with an 11 kW onboard charger into a 22 kW wallbox and it charges at 11 kW. The extra capacity does nothing. You’ve paid for a bigger unit, a three-phase supply, and a heavier circuit to deliver power the car will not accept.
The list of EVs that genuinely accept 22 kW AC is short and mostly specialist. If your car isn’t on it, a 22 kW charger is capacity you can’t use.
The comparison
| 7 kW single-phase | 11 kW three-phase | 22 kW three-phase | |
|---|---|---|---|
| Supply required | Single-phase — what most homes have | Three-phase | Three-phase |
| Current draw | 32 A | 16 A per phase | 32 A per phase |
| Range added per hour | ≈ 40 km | ≈ 60 km | ≈ 100 km |
| Overnight (8 hrs) | ≈ 320 km | ≈ 480 km | ≈ 800 km |
| Cars that can use full speed | Effectively all | Most modern EVs | A small handful |
| Install complexity | Standard dedicated circuit | Requires three-phase supply | Three-phase plus heavier circuit |
Range figures are approximate and vary by vehicle efficiency. The row that matters most is the second-last one.
The counterintuitive part: 11 kW can be slower than 7 kW
This one surprises people, and it’s the reason “bigger number equals faster” fails as a rule of thumb.
An 11 kW three-phase charger delivers 16 amps on each of three phases. If your car has a single-phase onboard charger — common on more affordable EVs — it can only draw from one of those phases. Sixteen amps at 230 volts is about 3.7 kW.
A 7 kW single-phase charger delivers 32 amps on one phase. Same car, roughly 7.3 kW. Nearly twice as fast as the 11 kW unit.
A 22 kW charger also runs 32 amps per phase, so a single-phase car gets its full 7.3 kW there too. But it needs three-phase supply to deliver something a 7 kW unit already achieves for that vehicle.
Work out what your car can actually take
- Find the onboard AC charger rating in your owner’s manual or spec sheet — sometimes listed as “AC charging” or “onboard charger.”
- If it says 7.4 kW or less, your car is almost certainly single-phase. A 7 kW charger gives you its maximum speed.
- If it says 11 kW, you have a three-phase onboard charger. An 11 kW unit matches it exactly; 22 kW adds nothing.
- If it says 22 kW, you’re in the minority that can genuinely use a 22 kW charger — assuming your home has three-phase supply.
- Check your switchboard for single or three-phase: one main switch generally means single-phase, three linked switches means three-phase.
That first number is your ceiling. Everything else is about whether your home can deliver up to it.
Do the maths on your actual driving
Charging speed matters far less at home than most buyers expect, because the car is parked for so long.
At 7 kW you’re adding roughly 40 km of range per hour. A 100 km day is a 2.5-hour charge. Even 200 km — a heavy day for most drivers — is around five hours, comfortably done overnight while you sleep. The car doesn’t care whether it finished at midnight or 4am.
Faster charging only matters when you need a large top-up inside a narrow window. That’s a real scenario for some households, but it’s worth being honest about how often it actually happens to you rather than paying for the capability speculatively.
What three-phase actually involves
Before booking EV charger installation, this is the constraint worth understanding.
If your home is single-phase and you want 11 kW or 22 kW, you need a supply upgrade — and that’s a materially bigger job than installing a charger. It involves Energex, new supply infrastructure, and switchboard work, not just a different wallbox.
Our guide on whether you need a switchboard upgrade before an EV charger covers how to check what your board can handle, including the load calculation.
When 22 kW genuinely makes sense
- Your car actually accepts 22 kW AC — verified on the spec sheet, not assumed
- You already have three-phase supply, so there’s no upgrade cost to justify
- Multiple EVs sharing one charger, where total throughput matters more than individual speed
- Genuinely tight charging windows — commercial use, rideshare, or a vehicle that turns around several times a day
- Commercial or strata installations, where load management across several bays changes the calculation entirely
Outside those situations, the additional cost buys capability that sits unused.
Before you buy any charger
- Confirm your car’s onboard AC charger rating — it caps everything downstream
- Confirm whether your home is single or three-phase
- Get the switchboard assessed before ordering, not after
- Remember all EVs sold in Australia use the same Type 2 plug — choose on capability, not badge
What we recommend
For the overwhelming majority of Gold Coast and SEQ homes: a 7 kW single-phase charger on a dedicated circuit. It delivers full speed for most cars on the road, works with the supply nearly every home already has, and adds enough range overnight to cover any normal driving day.
We’ll tell you when the bigger unit is worth it. Mostly, it isn’t — and recommending it anyway would mean charging you for a three-phase upgrade your car can’t take advantage of.
For the full compliance picture on any install, see our guide on EV charger installation requirements in Australia.
Frequently asked questions
Will a 22kW charger charge my car faster than a 7kW one?
Only if your car’s onboard charger can accept more than 7 kW. The onboard charger is a fixed component in the vehicle and caps charging speed regardless of the wallbox. Most EVs top out at 11 kW AC, and only a small handful accept the full 22 kW.
Can a Tesla use a 22kW charger?
Model 3 and Model Y are limited to 11 kW AC by their onboard chargers. Plugged into a 22 kW unit they’ll charge at 11 kW — the extra capacity goes unused. A 22 kW charger provides no benefit for these vehicles.
Is an 11kW charger always faster than a 7kW one?
No — and this catches people out. An 11 kW three-phase unit delivers 16 A per phase. A car with a single-phase onboard charger draws from one phase only, giving about 3.7 kW. The same car on a 7 kW single-phase charger draws 32 A and gets roughly 7.3 kW — nearly twice as fast.
How do I find out what my car’s onboard charger is rated at?
Check the owner’s manual or manufacturer spec sheet, usually listed under “AC charging” or “onboard charger.” Ratings of 7.4 kW or below generally indicate a single-phase onboard charger; 11 kW or above indicates three-phase. That figure is your maximum home charging speed.
Do I need three-phase power for a home EV charger?
Not for a 7 kW charger, which runs on the single-phase supply most Australian homes already have. Three-phase is only required for 11 kW or 22 kW units — and upgrading to three-phase is a substantial job involving Energex and new supply infrastructure, not just a switchboard change.
Will a 7kW charger be enough for daily driving?
For almost all households, yes. At roughly 40 km of range added per hour, a 100 km day charges in about 2.5 hours and even a 200 km day is around five hours — comfortably overnight. Faster charging only matters when you need a large top-up in a narrow window.
Not sure which your home can support? Call us — Byron checks the switchboard and tells you honestly what’s worth installing.
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