Few things frustrate drivers more than arriving at a charger and finding it occupied by a car that finished charging an hour ago. For operators, the same car is a problem too: a blocked charger earns nothing. Idle fees, also called blocking or overstay fees, are the standard answer.
This guide explains how idle fees work, how to design them so they change behaviour without angering customers, and what your charging software needs to apply them correctly.
- An idle fee is a time-based charge that starts after charging ends and a grace period has passed.
- Typical grace periods are 10–30 minutes on DC and longer on AC; rates are usually per minute with an optional cap.
- Detect idle time from charger status and meter data, not only from session duration.
- Announce the fee clearly before the session starts; surprises create complaints and chargebacks.
What is an idle fee?
An idle fee is charged for the time a vehicle stays connected to a charger without drawing meaningful energy. It is separate from the energy price. The goal is not extra revenue but turnover: a free charger serves the next customer and earns from them.
In the EU, the AFIR regulation explicitly allows a time-based fee to discourage occupation at chargers of 50 kW and above, on top of the per-kWh price, as long as it is transparent and shown in advance.
When idle fees make sense
- DC fast chargers: high investment, high demand and short typical sessions make blocking costly.
- Busy urban AC chargers: on-street points shared by many residents.
- Retail and destination sites at peak hours: when the number of EVs exceeds the number of chargers.
Idle fees are usually unnecessary at overnight residential chargers, at fleet depots where the operator controls scheduling, or at workplace chargers with a booking system.
Designing the fee
| Parameter | Typical range | Notes |
|---|---|---|
| Grace period (DC) | 5–15 minutes | Time to return to the car after a notification |
| Grace period (AC) | 30–120 minutes | Longer, as drivers often shop or work nearby |
| Rate | Per minute | High enough to matter, low enough to be fair |
| Cap | Optional maximum per session | Prevents extreme bills and disputes |
| Active hours | All day or daytime only | Night exemptions suit residential AC sites |
A simple rule of thumb: the idle fee per minute should make staying longer clearly more expensive than moving the car, but should not exceed the revenue the charger would earn in the same time from another customer.
Detecting idle time correctly
The most common technical mistake is to charge for time after the session's start, or after the car reaches a fixed duration. Charging slows down as the battery fills, and some vehicles pause and resume. A fair idle fee starts only when charging has genuinely ended.
With OCPP, your CSMS can determine this from several signals:
- Connector status: in OCPP 1.6, a change from
ChargingtoSuspendedEVorFinishingsuggests the car has stopped accepting energy. See our guide to StatusNotification and connector statuses. - Meter values: power dropping close to zero for several minutes confirms it. Our article on OCPP MeterValues explains the data.
- Transaction events: in OCPP 2.0.1, TransactionEvent messages report charging state changes such as EVConnected or SuspendedEV.
Combining status and meter data avoids charging drivers whose car is simply charging slowly at a high state of charge.
Communicating idle fees
- Before the session: show the idle fee, grace period and cap on the charger screen, payment page and app.
- During the session: send a notification when charging is almost complete.
- When charging ends: notify the driver that the grace period has started.
- On the receipt: list idle minutes and the fee separately from energy.
Clear communication turns idle fees from a source of complaints into a respected rule. Many drivers welcome them, because they make it more likely that a charger will be free when they need it.
Exceptions and fairness
- Do not charge idle fees when the fault is on your side, for example if a charger fails to release the cable. Our guide to releasing a stuck cable remotely helps resolve these cases quickly.
- Consider exemptions for drivers with disabilities or for accessible bays with different usage patterns.
- Review disputed sessions using raw status and meter logs, which show exactly when charging ended.
Measuring the effect
Track average idle minutes per session, the share of sessions that incur a fee and charger availability at peak hours before and after introduction. A successful idle fee reduces blocking without becoming a large share of revenue. If idle fees are a major income line, the grace period may be too short or the communication unclear.
Frequently asked questions
Are idle fees legal?
In most markets, yes, provided they are transparent and shown before charging starts. In the EU, AFIR allows a time-based fee to discourage occupation at fast chargers. Check local consumer rules for display requirements.
How long should the grace period be?
For DC fast chargers, 5–15 minutes is common. For AC chargers, where drivers often park for longer activities, 30–120 minutes is typical.
Should idle fees apply at night?
At residential AC chargers, many operators suspend idle fees overnight because drivers cannot reasonably move their car. At busy DC sites, fees usually apply around the clock.
What if the car is still charging slowly?
A well-designed system only starts idle time when charging has really ended, using connector status and meter data, so slow charging near a full battery is not penalised.
Apply idle fees automatically from live OCPP status and meter data, with clear receipts for drivers. Explore Üreticy OCPP software or contact us to see it in action.