Your provider announces four hours of internet maintenance and you need the car in the morning. Ideally, you have already tested what happens: whether charging can start and what power to expect. That is the practical value of operation without a connection, or offline operation.
Losing the internet is not the same as losing electricity. The charger may still have power, but its response depends on model, software, access method and energy management together. Clarify this before an outage.
First check whether the charger itself lost connectivity
Fixed-line maintenance does not tell you what happens to a charger using a mobile network. Your phone might be offline while everything in the garage continues normally.
Start with the state of your own device. Which network does it use, when did it last report and what does it show locally? If the building has lost power, normal grid charging also lacks its energy supply.
In our example, only the charger's data connection disappears for four hours; electricity remains available throughout. We retain that distinction in the calculation.
Start with the preconfigured current limit
Zaptec documents a separate offline charging current and phase setting, with automatic allocation. Manual override is for exceptional cases; combined charger current must not exceed the installation fuse limit (Setting offline current and phase).
As a buyer, establish what applies to your installation: the current available offline, the phase used and whether the car's minimum is reached. Agree these points with the installer or operator.
At handover, learn what to expect without connectivity. If offline charging uses less current, allow for that before departure.
How much energy fits into four hours?
In our example, a professional has verified 10 A single-phase offline charging for a particular configuration. This is neither a factory default for a Zaptec model nor a recommended setting.
At a nominal 230 V, that is about 2.3 kW. Four hours of continuous charging delivers 9.2 kWh on the alternating-current, or AC, side. Losses affect what is stored in the battery.
Suppose you planned to deliver 12 kWh over the same four hours at the same measurement point. Offline operation leaves a 2.8 kWh shortfall. If the journey needs it, charge earlier or later to make it up.
Knowing the offline current limit lets you allow more time before the outage, using the power verified for your system.
Authorisation still matters after the key is read
Available current is only one condition. Check how a start is authorised when the central service is unavailable.
In Zaptec's webhook authentication mode, which delegates authorisation to an external system, a separate offline option can allow any user or card to charge when connectivity is lost (External authentication and offline configuration). That applies to this mode; understand the solution used in your system.
In Go 2 direct OCPP mode, where the charger connects to an external central system, that system must also have successfully accepted the charger at least once (Go 2 OCPP operation). A new, uncommissioned installation therefore differs from a brief outage on a charger used for months.
A request saved on your phone must still reach the device
When the charger is offline, a remote current change sent through an API—software interface—cannot reach it (Zaptec dynamic control). Saving the change on the phone does not prove the charger applied it.
During the four hours, you rely on what was configured beforehand. Requesting more current remotely does not by itself make charging faster.
Check scheduling against the relevant mode documentation too. The cited Zaptec guide requires an online connection for the schedule it describes (Scheduling and connectivity). At handover, establish how scheduled charging behaves offline.
Include reconnection in the test
On a quiet day, test with the installer what happens when connectivity is lost, whether charging starts with your identifier and what occurs on reconnection. Electrical protection and shared power limits must remain in force.
Record the model, version, offline allowance and outcome. After reconnection, find the current state and affected session. Keep a short user note so you know what to expect the next morning when the internet fails.
Does charging without the internet matter to you?
On our contact page, give the Zaptec model, intended use and whether one or several chargers share the connection. We can help compile the questions needed for selection and the installer discussion.
