In short: in 150 kW vs 350 kW comparisons, a 350 kW charger only charges faster than a 150 kW one if the vehicle can accept more than 150 kW, and only for the part of the session where its battery allows it. Published peaks for popular models range from about 128 kW to 260 kW, well short of 350 kW. For most sites, 150 kW chargers, or power-sharing units that can give some vehicles more, offer better value. Reserve the highest power for locations where time matters most and the vehicles can use it.
Charger power ratings are an easy way to compare products, but they are a poor guide to how quickly drivers will actually leave. This article explains why, and how to choose. For the UK definitions of each power band, see rapid vs ultra-rapid charging.
Why doesn’t a bigger charger always charge faster?
Two limits apply in every session: what the charger can supply and what the vehicle can accept. The lower one wins. As IONITY puts it, the actual charging speed depends on the voltage and current limits of your electric vehicle, however much power the charger can deliver.
The vehicle’s limit also changes during the session. Power is usually highest when the battery is fairly empty and falls as it fills. IONITY notes that charging from 80% to 100% takes just as long as from 20% to 80%. So a vehicle’s peak rating is reached only for part of the stop.
What can vehicles actually accept?
Peak rates vary widely, even within one manufacturer’s range.
| Vehicle | Stated peak DC power | Source |
|---|---|---|
| Hyundai IONIQ 5 | Up to 260 kW | Hyundai UK |
| Kia EV6 | 258 kW | Kia UK charging table |
| Kia EV9 | 210 kW | |
| Kia EV3, EV4, EV5 | About 127 to 128 kW |
That shapes the 150 kW vs 350 kW choice: even the fastest of these sits well below 350 kW, and the smaller models would charge no faster on a 350 kW unit than on a 150 kW one. Hyundai itself notes that a 350 kW charger is needed for the IONIQ 5’s quickest times, because a 150 kW unit would cap it. Check the published figures for the vehicles you expect at your site, including any vans, before choosing charger power.
Where does 350 kW make sense?
- Motorway and major-route hubs, where drivers want the shortest stop and many visiting cars can exceed 150 kW.
- Premium sites competing on speed, where charging time is part of the offer.
- Future-proofing at a few bays, as more high-voltage vehicles arrive.
Where is 150 kW the better choice?
- Retail and leisure sites, where drivers stay 30 minutes or more anyway.
- Depots and fleet hubs, where vehicle types are known and few exceed 150 kW.
- Sites with limited grid capacity, where each kW of connection is expensive.
What about power sharing?
Many chargers now share a total power between two outlets, or a central cabinet feeds several dispensers. A vehicle that can accept high power gets it, while one that cannot leaves the rest for its neighbour. This often gives most of the benefit of very high power at a fraction of the connection size. We compare the designs in distributed vs standalone chargers.
How do the costs compare?
Higher-power chargers cost more to buy, need larger cables and switchgear, and draw on more grid capacity, which may be the most expensive part of all. Weigh that against the extra revenue from shorter stops, which depends on how many visitors can use the extra power. For hub-wide planning, see our guide to planning an ultra-fast charging hub.
Quick comparison
| Factor | 150 kW | 350 kW |
|---|---|---|
| Faster for most current cars? | Close to their real limit for many | Only for vehicles above 150 kW |
| Hardware and installation cost | Lower | Higher |
| Grid capacity per bay | Lower | Higher |
| Best for | Retail, depots, constrained sites | Major-route hubs, premium sites |
Frequently asked questions
Will a 350 kW charger damage a car that only accepts less?
No. The vehicle tells the charger what it can accept, and the charger delivers no more than that.
Why did my car charge slower than its maximum?
Common reasons are a battery that is already fairly full, a cold battery, or a charger sharing power with another vehicle.
Should I future-proof with 350 kW everywhere?
Usually not. Install the ducting and capacity for future upgrades at a few bays, and buy the power you can use today.
Our solution recommendations service matches charger power to the vehicles and visits you expect. Tell us about your site.
