Your app estimated 25 minutes. You sat for 50. Nothing was broken. Nobody was ahead of you. The charger just never delivered what the sign said it would.
This is the most common complaint in our session data, and it has five specific causes. Every one of them is predictable before you plug in. Here is what actually happened, in order of how often we see it.
1. The charger never delivered its rated speed
The number on the cabinet is a maximum, not a promise. A “350 kW” charger is rated to deliver 350 kW under ideal conditions to a car that can accept it. Most sessions never get close.
Our telemetry shows how wide the gap runs. Across networks, the share of stalls that actually hit their rated speed ranges from 94% at Tesla Superchargers down to 48% at Blink. Electrify America’s 350 kW cabinets average 263 kW delivered. EVgo’s average 198 kW. The full network-by-network numbers are in our network comparison table, under “Delivered speed (measured).”
If your route plan assumed rated speed and the stall delivered 60% of it, your 25-minute stop became 40 minutes before anything else went wrong.
How to spot it: check the delivered-speed figures for the network before you rely on it. Plan on measured averages, not the number on the cabinet.
2. Your battery was cold
Batteries charge fastest between roughly 68°F and 95°F internal temperature. Below that, the battery management system throttles the charge to protect the cells. The colder the pack, the harder the throttle.
This is the single biggest factor on winter mountain corridors. On a January morning on I-90 at Snoqualmie Pass or I-70 through the Eisenhower Tunnel approach, an unconditioned pack can accept 30–50% less power than the same pack in summer. The charger is fine. The car is protecting itself.
How to spot it: precondition. If your car supports battery preconditioning when you set a charger as the navigation destination, use it every time in cold weather. Tesla does this automatically. Most other EVs only do it when the charger is set in the native nav — not in a third-party app.
3. You charged past 80%
Charging is not linear. Every EV charges fastest in the low and middle of the pack, then tapers hard as it fills. The last 20% of a battery routinely takes as long as the first 60%.
Apps estimate session time to your target charge level. If you set 100% for comfort, you signed up for the slowest portion of the entire curve. On a road trip, charging from 10% to 60% twice is almost always faster than charging 10% to 100% once.
How to spot it: this one is on the route plan, not the hardware. Set arrival buffers, not full charges. Our DC fast charging guide covers the charging curve in detail.
4. The cabinet was splitting power with the stall next to you
Many DC fast charging sites run two stalls off one power cabinet. When both stalls are occupied, the cabinet splits its output. A 350 kW cabinet shared two ways can drop each car to 175 kW or less, depending on the hardware generation.
This is why a half-full site can be slower than a busy Tesla site. Superchargers V3 and newer do not split power between stalls. Many Electrify America, EVgo, and ChargePoint sites still do, especially hardware installed before 2023.
How to spot it: look at the stall numbering. Paired stalls are usually labeled like 1A/1B, 2A/2B. If the site is half full, plug into a stall whose pair is empty.
5. The app’s estimate was never real
The time estimate in a charging app is a model. It assumes rated charger output, a warm battery, and your car’s ideal charging curve. It rarely accounts for shared cabinets, cold packs, or the measured delivery gap in cause #1.
Stack two of these factors — a cold battery on a shared cabinet — and a 25-minute estimate becomes 50 minutes with nothing malfunctioning. The estimate was fiction from the start.
How to spot it: treat app estimates as best-case. On corridor drives, add a 50% buffer to every planned stop in winter, and 25% in summer. Our corridor guides for I-90, I-84, I-70, and I-5 flag the specific stops where single-cabinet sites and elevation make this worse.
The one-minute version
A slow charging stop is almost never a mystery. Before you pull in: check the network’s measured delivered speed, not its rated speed. Precondition the battery in cold weather. Charge to 60–80%, not 100%. Pick a stall that is not sharing a cabinet. Then add a buffer to whatever the app tells you, because the app assumes none of this happens.
The networks that consistently close the gap between promised and delivered speed are ranked in our network comparison. That gap — not the number on the cabinet — is what decides how long you sit.