How Fast Does the BYD Dolphin Surf Fast Charge With a Cold LFP Battery? I Tested It
After a long road trip, my BYD Dolphin Surf sat in a parking lot all night. In the morning I plugged it straight into a DC fast charger without warming the LFP battery, and watched the charging power kilowatt by kilowatt. The result beat the official spec sheet.
LFP batteries have a bad reputation for DC fast charging when they aren't warm: the power drops, the session drags on, and the driver stares at the screen. I wanted to see how big that problem really is on the BYD Dolphin Surf. So after a long road trip across Romania to Timișoara, I left the car parked overnight and, at 7:50 in the morning, moved it a few meters straight to a fast charger. No drive beforehand, no battery warmed up by the motorway. Just a plug and a stopwatch.
The car and the charger
I tested the Boost version, the middle trim. According to "BYD Europe", it has a 65 kW (88 hp) motor, a 43.2 kWh Blade LFP battery and 322 km (200 miles) of WLTP combined range. BYD quotes a maximum DC charging rate of 85 kW for the Boost, with 10–80% in about 30 minutes and 30–80% in around 22 minutes. Every version gets an 11 kW onboard AC charger.
The charger was an "E.ON Drive" unit in Moșnița Nouă, near Timișoara, rated at roughly 200 kW, far more than the car can accept. It was about 21°C (70°F) outside, and the car hadn't moved since 10 PM the night before. The battery had not been preconditioned, so it started from whatever temperature it had settled to overnight.
The power, step by step
I plugged in at 9%. From my experience, at this state of charge the car should pull about 87 kW with the battery in ideal shape. Here's how it went:
- right after plugging in: 62 kW;
- a few seconds later: 63, then 76 kW;
- after a minute or so: a steady 75–76 kW;
- a bit later: 77 kW;
- session peak: 89 kW.
In 5 minutes the battery went from 9% to 25%. That's 16 percentage points in the time it takes to drink an espresso. The peak slightly above BYD's official 85 kW isn't a big deal: it's a momentary reading on the charger screen, and automakers usually list a rated figure rather than short spikes.
How the road trip went
This clip is really the tail end of a roughly 670 km (416-mile) trip from northeastern Romania to Timișoara, over the mountains via Toplița. It took me about 10 hours including stops, the same as it used to take in my old gasoline and diesel cars. The longest charging stop on the way was a little over 20 minutes. I had sessions of 5, 17 and 24 minutes, and one of them hit 87.3 kW.
On two-lane national roads I never saw the display go above 14 kWh/100 km (about 4.4 miles per kWh). The trip computer showed an average speed of 83 km/h (52 mph) over three hours of driving. My advice for the highway, especially on vacation: 110 km/h (68 mph), 120 km/h (75 mph) at most. That's the sweet spot between energy use and time spent at chargers.
Other things I noticed
- The efficiency readout only covers the last 50 km. I'd love a cumulative, resettable trip average so I could see the number for a whole journey. Hopefully an update fixes that.
- Software updates really matter. Compared with my December 2025 test, the car now shows the outside temperature correctly, and the navigation has become very good. It tells you your arrival percentage at each charger and how long to stay. At 25% it suggested a 42-minute stop, which I didn't need.
- The cabin is simple but practical: easy-to-clean surfaces, comfortable faux leather and level armrests. At 1.80 m (5'11"), I had plenty of legroom in the back.
- The suspension is soft over bumps, yet the car stays composed in corners, including the Toplița mountain switchbacks.
- Equipment: the Boost has a rear camera and rear parking sensors, but no front camera.
- The Tesla Wall Connector at my destination wouldn't start a session. It may be a setting on my own charger or a compatibility issue, so check before you rely on one.
What it means for drivers
The fear that a "cold" LFP battery will leave you stuck at a charger for ages didn't hold up in this test. After a night parked and no preparation at all, the Dolphin Surf started above 60 kW and climbed quickly to the maker's quoted maximum. To be fair, 21°C isn't winter: below freezing the power can drop further, and battery preheating helps if your car offers it after recent updates.
For a 4-meter (13-foot) car with a 43.2 kWh battery, the smartest strategy is short, frequent stops of 15–25 minutes at a low state of charge, where charging is fastest. Keep in mind that WLTP ratings are European figures and tend to be more optimistic than US EPA estimates. Drive it that way and the Dolphin Surf can be the family's road-trip car, not just the city runabout. The full story of the trip, with every stop, is in the dedicated videos on my channel.
