Why is my EV charging slower than the DC charger's rating?

Short answer: a DC charger almost never charges a car at the number on its badge, and that is usually not a fault. The car sets the pace, not the charger. A session runs slower than the badge when the car's own limit is lower, when the battery is too full, too empty, too cold or too hot, when a second car is sharing the charger, or when the site has been set to draw less power than the charger can. Only after ruling those out is it worth calling it a fault. This guide goes through them in the order we check them.

1. The car's own limit

Every EV has a maximum DC rate set by its battery and its charging hardware. Plug a car that takes 50 kW into a 120 kW charger and you get 50 kW, at best. It is the most common reason a session looks slow. Find your car in the table below. The column "Takes up to" is the ceiling for your session, whatever charger you use.

2. How full the battery is

A car draws its peak rate only in the middle of the battery. Below about 10% some cars start gently. Above about 80% every car cuts the current hard to protect the cells, and the last 20% can take as long as the first 70%. If you arrived at 60% and the screen shows a modest figure, the car is doing what it should. On a road trip, unplug at 80% and drive on: it is faster overall, and it frees the bay for the next driver.

3. Battery temperature

Lithium cells accept current slowly when they are cold, and the car protects them by asking for less. A car that has been parked all night in a Delhi or Srinagar winter will charge slower for the first part of the session than the same car after an hour on the highway. Heat works the other way round: a car that has been driven hard in a Rajasthan summer may hold its rate down to cool the pack. Some cars can warm or cool the battery on the way to a charger if you set it as the destination in the car's own navigation.

4. Another car on the same charger

A dual-gun charger's rating is what its two guns deliver together. If another car is plugged into the other gun and both are hungry, they share it. Two mass-market cars on a Nova 120 rarely notice. Two premium SUVs on one charger both will. We explain how sharing works in one dual-gun charger or two single ones.

5. The site's power limit

Some sites have less electricity than their chargers could use, and the owner caps the chargers to stay inside the sanctioned load. A charger can also lower its own output when its cabinet runs hot, for example when its air filters are clogged on a dusty site. Both look like a slow charger to the driver. Neither is visible from the car. If the same car charges faster at another site of the same charger model, this is the likely cause, and the site owner can see it in the dashboard.

6. Then, and only then, a fault

A worn gun that does not seat firmly, a damaged cable that runs hot, or a failed power module can all cut the rate. These are rarer than any of the causes above, and they usually show other symptoms: a session that stops and restarts, an error on the screen, a gun that is warm to the touch. If you see that, stop the session, note the charger's ID from the screen, and tell the site owner or the operator in the app.

For site owners

When a driver says your charger is slow, check in this order: what car it was and its limit in the table above; the state of charge at the start; whether the other gun was busy; any power cap you have set; the cabinet temperature and filters; then the fault log. Most complaints end at the first or second step, and a calm explanation keeps a customer. Our guide to keeping a DC charger running covers the routine checks that prevent the rest.