Smart tariff EV charging: how off-peak schedules work with a home charger

Smart tariff EV charging is about timing a charge for a preferred electricity window. For many UK home charging customers, that means plugging in earlier and letting charging start later.

The charger, app and vehicle each have a role. Understanding those roles makes off-peak charging easier to trust.

Quick answer: how does smart tariff EV charging work?

Smart tariff EV charging uses a saved schedule, app-led instruction or tariff-aware charging window to delay charging until the preferred time. The charger follows the charging instruction it has been given, but the vehicle still decides whether it will accept energy when the charger offers it.

That means "not charging yet" can be expected if the off-peak window has not opened.

The tariff chooses the window, the charger follows the instruction

The energy tariff defines the commercial reason to charge at a certain time. The charger does not control the tariff itself.

The charger can help by following the configured charging window, showing what it is waiting for, and making the planned session easier to understand in the app.

For PlugStream customers, the practical aim is straightforward: make it clear whether the charger is waiting for a schedule, waiting for the vehicle, paused by a site condition or asking for attention.

Why charging may not start immediately

With tariff-aware charging, an immediate start is often not the goal.

The charger may wait because:

• the preferred charging window has not opened
• a saved schedule is active
• a smart charging mode is delaying the session
• the vehicle is not requesting energy
• the site is currently load-limited
• the charger is offline and cannot show the latest app status

If the charger is waiting for a planned window, that is expected behaviour. If the planned window has opened and charging still does not start, the next checks are the vehicle, cable, connectivity and site power conditions.

Vehicle settings still matter

Many vehicles have their own charging limits, departure times or app-based schedules.

If the vehicle has a conflicting setting, the charger may offer energy at the right time but the vehicle may not accept it. That can make a charger-side schedule look wrong when the vehicle is actually controlling the result.

Read the related guide: Waiting for vehicle: what your EV charger can and cannot control.

How Charger Readiness helps

Charger Readiness helps explain whether the charger appears ready for the next charging window.

That matters for smart tariff charging because the customer often needs confidence before the off-peak window begins. A clearer readiness state can help show whether the charger is online, waiting correctly, paused, or blocked by something that needs attention.

Read the product update: Introducing Charger Readiness in MyPlugStream.

Where Vehicle Wake Assist helps

Some vehicles can sleep between plug-in and a delayed charging window.

Vehicle Wake Assist is designed to help PlugStream manage that handover more gracefully by checking for sleeping-vehicle behaviour and retrying the charger-side session path where supported.

It is not a guarantee for every vehicle. It is a practical resilience feature for supported delayed-start scenarios.

Smart tariff charging checklist

Before assuming the tariff setup or charger has failed, check:

1. the planned off-peak or preferred charging window
2. the saved charger schedule or app-led charging mode
3. the vehicle's own charging schedule and charge limit
4. whether the charger is online
5. whether load management is currently limiting output
6. whether the app shows waiting for schedule, waiting for vehicle or paused

Related PlugStream guidance

Start with the wider cluster: EV charging features guide.

Then read Scheduled EV charging not starting, EV charger load management and Vehicle Wake Assist for the common reasons delayed charging needs more context.