Charger, tariff or car: which one holds your schedule?

An off-peak EV tariff only saves you money if something is switching your charging on and off at the right times. Find out whether that job falls to your charger or your car, and what to check when it stops working.

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Who actually controls when the charger starts: the unit or the car

An off-peak tariff only pays off if something switches the charger on at the cheap hours and off again before the peak rate returns. That job falls to one of two places: the charger itself, or the car plugged into it.

Charger-side scheduling

Here the charger holds the timetable. It connects to a network through its own app, sometimes called a smart charge point, and it is told the off-peak hours directly. At the set time it opens or closes the circuit at the socket, whatever the car is doing and whatever timer the car might also have running.

Car-side scheduling

Here the car holds the timetable instead, through its own dashboard or app. The charger just supplies current whenever the car asks for it. The charger does not need to know the tariff hours at all; the car works that out and draws power only when it chooses to.

A household needs one of these two working. Where a charger's own schedule and the car's own timer are both switched on, whichever is set to start later or stop earlier decides what actually happens, and a driver can end up paying the peak rate without anything having gone wrong with the equipment.

This is something you can check yourself, by looking in the charger's app and in the car's own charging settings to see which of them, if either, has an active timer. The charger-tariff scheduling guide sets out how each named EV tariff expects this to work, and the charger comparison table shows which units handle scheduling through their own app.

Scheduling route	Where it runs	Check before relying on it
Charger-side scheduling	Set through the charger's own app or built-in timer	The charger needs to stay connected to your home network, and the off-peak times must be entered correctly after any tariff change
Car-side scheduling	Set through the car's own timer or charging app	The charger has to be left in a mode that lets the car start the session itself.
Both set up at once	Charger and car each hold a schedule, usually aimed at the same window	If the two disagree on the time, whichever one starts the session first is the one actually in control that night
No smart scheduling	You plug in and start the charge yourself once the off-peak window opens	Depends on someone being around to start it, and on remembering when the window changes with the clocks or a tariff update

This sets out the mechanism behind each route. Which route a given tariff uses, and which chargers it talks to directly, is covered in the sections below, each against its own source and date.

What happens to your schedule when you switch supplier

The schedule doesn't belong to the supplier

Moving your electricity account to a new supplier does not mean starting your charging setup again. The Electric Vehicles (Smart Charge Points) Regulations 2021 require a smart charge point to keep working as a smart charge point whatever supplier you are with. They apply in Great Britain; they do not cover Northern Ireland.

That is worth knowing because a schedule can feel like it belongs to the tariff you switched to, when really it belongs to the charger or to the car. The supplier sets the off-peak window and the rate. The device holding the schedule is a separate question, and it does not change just because you changed who you pay.

What to update when you switch

A supplier switch usually leaves you with one thing to do: tell whichever device is holding the schedule, the charger's app or the car's own timer, what the new off-peak window is. Nothing about the physical installation needs attention.

Find your new tariff's off-peak window and rate from the supplier's own documentation
Check whether the charger or the car is currently set to charge in that window
Update the timer on that device, since only one of them needs to hold the schedule

You can find out which device is doing the work by checking the charger-side vs car-side scheduling explanation, which sets out how to tell the two apart.

When the schedule stops working after a switch

Sometimes the charging simply does not shift into the new off-peak window. A few things cause this: the charger's app only recognises a short list of named tariffs and your new supplier isn't on it, the charger lost its network connection during the switch and needs reconnecting, or the car's timer was never updated because the household assumed the charger was holding the schedule. Checking which chargers integrate directly with which tariffs is something you can do yourself, using a comparison of charge point specifications including scheduling route and tariff integrations. Reconnecting a charger that has dropped off the network is also something a householder can usually do without calling anyone out.

Common questions about who holds the schedule

How can I tell whether the charger or the car is holding the schedule?

Look at where the start and stop times were actually set. If you entered the off-peak window in the charger's own app, the charger is running the schedule and will try to charge whenever it next gets the chance, regardless of what the car's timer says. If you set a charging timer in the car instead, the car decides when to draw power and the charger simply delivers it on request. Running both at once, with different times entered in each, is the most common reason a charge starts late or not at all. The comparison table on our charger comparison page shows which scheduling route each charger is built around, and our guide to charger-side vs car-side scheduling goes through both routes in detail.

What happens if the charger loses its network connection?

A charger that holds the schedule itself needs a working internet connection, usually Wi-Fi or a mobile signal, to receive and keep that schedule. If the connection drops, most chargers fall back to charging as soon as the car is plugged in, which can mean a full-rate session during peak hours. A car-side schedule is not affected by the charger's connection, because the car is the one deciding when to draw power.

What happens if my tariff is withdrawn or its off-peak window changes?

Nothing on the charger or the car updates automatically. If the tariff that set your off-peak hours is withdrawn or the window moves, you need to go back into whichever app is holding the schedule, the charger's or the car's, and enter the new times yourself. Until that happens, the equipment keeps charging on the old window, which may now fall in peak hours.

Does switching electricity supplier affect the schedule?

The Electric Vehicles (Smart Charge Points) Regulations 2021 require a smart charge point to keep its smart charging and scheduling functions when you move to a new supplier, and this applies across Great Britain but not Northern Ireland. The charger itself should carry on working. What usually needs attention is the tariff integration: if the charger or car was linked directly to your previous supplier's off-peak rate, you will need to set up the new supplier's off-peak window by hand, or check whether the new tariff offers a direct link at all.

What should I check first if a charge stops happening during the off-peak window?

Start by confirming which device is meant to be holding the schedule, the charger's app or the car's own timer, since only one of them should be set. Then check that the times entered there still match your current tariff's off-peak window, and that the charger shows as connected to its network if it relies on one. A car-side schedule that has not been reset after a change of tariff, or a charger that has silently dropped its connection, account for most cases where a car simply does not charge when expected.