Public EV Charging: Uncomfortable Truths

Public EV charging works, but it is far less convenient, reliable, and cheap than most first-time buyers expect. The uncomfortable truths are that public chargers frequently fail, costs vary wildly by network and location, and the fastest charging speeds only happen under ideal conditions that rarely occur in real life.

The Reliability Problem

Public chargers fail more often than most drivers expect. Studies and user reports consistently show that a significant fraction of charging sessions end with an error, a dead screen, or a payment failure. The reasons are varied:

Broken connectors – cables get run over, yanked, or simply wear out.
Payment system issues – card readers fail, apps crash, or the network’s backend rejects a valid account.
Software bugs – chargers run firmware that can hang or reboot mid-session.
Vandalism and theft – cables are cut for copper, screens smashed.
Inadequate maintenance – many stations are rarely inspected, and faults go unfixed for weeks.

A 2023 survey by a major US auto club found that about 1 in 5 charging attempts failed. In practice, this means you cannot assume a charger will work just because it appears on a map. The map shows the location, not the status.

The Speed Myth: Tapering and Sharing

Chargers advertise peak power – 150 kW, 250 kW, 350 kW – but you rarely get that for more than a few minutes. The battery’s charging curve is not linear:

Below 10% – charging may be limited to protect the battery.
10% to 50% – the fastest part, often near the peak.
50% to 80% – power drops noticeably.
80% to 100% – very slow, sometimes under 50 kW, to prevent damage.

So a 150 kW charger might deliver 150 kW only between 10% and 40%, then taper to 80 kW at 60%, and 40 kW at 80%. The average over a 20%-80% session is typically 40-60% of the peak. Also, many stations share power between two stalls: if the adjacent car is charging, your speed drops by half.

Another factor is the car itself. Not every EV can accept 350 kW. Many popular models max out at 100-150 kW. You cannot charge faster than the car’s onboard limit, regardless of the charger’s rating.

Cost Variability and Hidden Fees

Public charging costs more than home charging and varies enormously. While home electricity in the US averages around $0.16/kWh, public DC fast chargers often charge $0.40-$0.60/kWh. Some networks charge by the minute instead, which can be cheaper or far more expensive depending on the charger’s speed.

Hidden fees add to the pain:

Idle fees – you are charged per minute after the car finishes charging if you do not move it. These can be $0.50-$1.00 per minute.
Session fees – a flat $1-$2 just to start a charge.
Membership fees – some networks require a monthly subscription for lower rates, which only pays off if you use them often.
Peak pricing – rates can double during high-demand hours.

To compare, charging a 75 kWh battery from 20% to 80% (45 kWh) at $0.50/kWh costs $22.50. At home, the same energy costs about $7.20. Over a year of regular public charging, that difference adds up to hundreds of dollars.

The Charging Etiquette and Availability Problem

Even when chargers work, you may not be able to use them. Lines are common at popular stations, especially on weekends and holidays. There is no reservation system on most networks, so you wait in your car or nearby. When you do get a spot, you face pressure to unplug as soon as your car hits 80% – because someone else is waiting.

Charging etiquette is a real issue:

ICEing – gasoline cars parked in EV spots, blocking access.
Cable length – some stations have short cables that only reach a charge port on a specific side of the car, so you may need to park awkwardly or wait for a different stall.
Charger hogging – people leaving their car plugged in for hours after reaching 100%.

These are not rare annoyances; they are common enough that many EV forums have dedicated threads on how to handle them.

How to Choose a Public Charger

Given all this, the smart approach is to plan ahead rather than rely on luck. Here is a practical checklist:

Check the app – most networks show real-time status and whether a stall is free. Use it before you arrive.
Filter by speed – look for 150 kW or higher if you want a quick top-up; 50 kW is fine for overnight or while shopping.
Read reviews – apps like PlugShare have user reports on which specific stalls work and which are broken.
Have a backup – plan a second station within 15 km in case the first is full or broken.
Know your car’s curve – if your car tapers early, stopping at 60% may be faster than waiting for 80%.
Check the price – the app usually shows the rate; compare per kWh vs per minute before plugging in.

Also, consider destination charging – slower AC chargers at hotels, malls, or workplaces. They are often free or cheap, and you can leave the car for hours. For daily use, this is far more convenient than a fast charger.

Frequently Asked Questions

Why is public charging so unreliable?

Chargers are complex devices with many failure points: payment systems, network connectivity, power electronics, and physical connectors. They are installed outdoors, exposed to weather, and often maintained by small teams that cannot keep up with faults. The industry is still young, and reliability standards are not yet as strict as for gas stations.

Is it cheaper to charge at home or in public?

Home charging is almost always cheaper, often by half or more. Public DC fast charging costs $0.40-$0.60/kWh, while home rates are typically $0.10-$0.25/kWh. The only exception is if you have free workplace charging or a promotional rate from a network.

How long does a typical public charge take?

On a 150 kW charger, adding 100 km of range takes about 10-15 minutes. A full 20%-80% charge on a 75 kWh battery takes 30-40 minutes. On a slower 50 kW charger, the same 20%-80% takes about 1 hour.

Can I charge any EV at any public charger?

Most public chargers use the CCS or CHAdeMO connector, but the Tesla Supercharger network uses its own plug. Tesla has opened many Superchargers to other EVs with an adapter, but not all. Always check the connector type before arriving.

What is an idle fee and how do I avoid it?

An idle fee is charged when your car is fully charged but still plugged in, to encourage you to free the spot. Rates can be $0.50-$1.00 per minute. Avoid it by setting a charge limit below 100% and moving your car as soon as the session ends.

Is it better to charge to 80% or 100% on a road trip?

For speed, stop at 80% – the last 20% takes as long as the first 60% due to taper. For battery health, keeping the state of charge below 100% for daily driving is recommended. On a road trip, if you need the extra range to reach the next charger, charge to 90-100%, but know it will be slow.

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.

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