EV Charger Preventive Maintenance: What Should Be Checked?

An EV charger failure rarely begins at the moment the equipment finally stops working. Before that happens, there may already be wear on a charging cable or connector, contamination, a cooling issue, unstable communications, an electrical deviation or another developing condition that has not yet resulted in a visible failure.

This is where preventive maintenance plays its role.

The purpose of preventive maintenance is not to repair a failure that has already occurred. It is to identify technical deviations, wear and developing issues early enough for them to be assessed and, where necessary, addressed before they lead to unplanned unavailability or a more serious fault.

That does not mean performing the same checklist on every EV charger.

An AC wallbox in an indoor corporate car park, a public AC charger outdoors and a high-power DC charging system differ in design, utilisation, operating environment and maintenance requirements.

Good preventive maintenance therefore starts not with a universal checklist, but with the specific equipment and the conditions in which it operates.

What Is the Difference Between Preventive Maintenance and EV Charger Repair?

Preventive maintenance and repair are related, but they serve different purposes.

Preventive maintenance is planned. It is carried out to assess technical condition and identify potential problems before a failure occurs.

Corrective maintenance begins after a fault or defect has been identified. Its purpose is to remove the cause and restore the required functionality.

A preventive inspection may, for example, identify damage or wear on a charging cable. Identifying the issue is part of preventive maintenance. Replacing the cable is a subsequent corrective action.

This distinction is also important when defining the service scope: preventive maintenance does not automatically mean that every defect identified and every required repair are included in the preventive service itself.

Why There Is No Universal Preventive Maintenance Schedule for Every EV Charger

Manufacturers define procedures and maintenance intervals for specific equipment. Requirements can differ even between product families from the same manufacturer.

For some systems, particular maintenance activities may be scheduled at defined intervals, while other components may require more frequent inspection or condition-based servicing.

Conditions at the specific site also matter.

Maintenance frequency may be influenced by:

• equipment model and design;
• AC or DC technology;
• intensity of use;
• indoor or outdoor installation;
• dust, moisture and contamination;
• temperature conditions;
• mechanical stress on cables and connectors;
• fault history;
• manufacturer recommendations and requirements;
• warranty conditions;
• condition of the associated electrical infrastructure.

For this reason, a statement such as “every EV charger must be serviced once a year” is too broad.

The more useful question is:

What preventive maintenance plan is appropriate for this specific equipment under these specific operating conditions?

What Does EV Charger Preventive Maintenance Include?

The exact scope should follow the manufacturer's documentation, the project design, the technical condition of the infrastructure and the agreed maintenance scope.

In practice, preventive maintenance may cover several main areas.

Visual Inspection of the Charging Equipment

The first step is often a physical inspection.

It can reveal issues that have not yet triggered an electronic fault or interrupted the charging service.

Depending on the equipment, the inspection may include:

• enclosure and external panels;
• signs of impact or other mechanical damage;
• mounting and general physical condition;
• doors, covers, locking mechanisms and seals;
• display, indicators and other user interfaces;
• contamination, moisture or other visible abnormalities.

For outdoor equipment, the operating environment is particularly important. Water, dust, temperature variation, contamination and mechanical exposure can gradually affect the condition of the system.

A visual inspection may appear simple, but it is an important part of manufacturer maintenance procedures precisely because some developing issues can be identified at this stage.

Charging Cable and Connector Inspection

The charging cable and connector are among the components with the most direct interaction with the user and vehicle.

They are connected, disconnected, moved and bent, and improper handling may also result in them being dropped or left on the ground.

Preventive inspection may check for:

• visible mechanical damage;
• cuts, abrasion or deformation;
• connector condition;
• contamination or foreign material;
• visible signs of overheating;
• cable mounting and general condition;
• cable-management or retraction mechanisms where fitted.

A damaged cable or connector should not be treated merely as a user inconvenience. Depending on the nature of the defect, use of the affected charging point may need to be restricted until a technical assessment and the necessary corrective action have been completed.

Inspection of the Electrical Infrastructure

An EV charger is part of a wider electrical system. Maintenance of charging infrastructure should therefore not automatically stop at the charger enclosure.

Depending on the project, equipment and agreed scope, technical inspection may include elements such as:

• power-supply connections;
• electrical distribution boards;
• protective devices;
• connections and terminals;
• protective conductors and earthing system;
• visible signs of overheating or damage;
• other parts of the electrical infrastructure associated with the charging system.

Not all of these activities form part of every standard charger preventive-maintenance visit.

The required inspections, measurements and tests should be determined according to the specific electrical installation, project design, applicable requirements, technical documentation and manufacturer instructions, and should be carried out by appropriately qualified personnel.

This is an important distinction:

Preventive maintenance of the charging equipment and technical inspection of the associated electrical infrastructure are related, but they are not necessarily the same activity or the same scope.

Cooling-System Inspection for DC Chargers

Power electronics in DC charging systems generate heat, making thermal management part of normal system operation.

Depending on the design, equipment may use fans, air filters, liquid cooling or another thermal-management architecture.

For relevant equipment, preventive maintenance may therefore include inspection of:

• air inlets and outlets;
• filters;
• fans;
• contamination;
• applicable cooling-system components;
• other components specified by the manufacturer.

There is no universal procedure here either. Whether a filter requires cleaning or replacement, and at what interval, depends on the specific equipment and operating conditions rather than on a general rule for all DC chargers.

Communications and Connectivity Checks

Modern charging infrastructure often depends on communication with a central management system.

A connectivity issue may not appear to be a hardware failure, but it can affect monitoring, management, authorisation or other operational functions.

Depending on the system architecture, checks may include:

• current connectivity;
• communication stability;
• available error messages;
• charger status information;
• history of communication interruptions;
• communication with the central management system.

Where a charger uses OCPP, the operational and diagnostic information available depends on the protocol version, the charging equipment and the specific implementation.

This information can help preventive maintenance reflect the actual behaviour of the system rather than relying only on what can be observed during a physical site inspection.

Configuration and Software Checks

The configuration of a connected EV charger forms part of its technical state.

Where applicable, checks may include:

• current configuration parameters;
• available faults or warnings;
• firmware/software version;
• connection to the management system;
• applicable manufacturer updates.

This does not mean that every newly available firmware version should automatically be installed.

An update should be assessed in the context of the specific equipment, manufacturer guidance, compatibility and the system's change-management procedures.

“An update is available” is not, by itself, a sufficient reason for an uncontrolled change to operational charging infrastructure.

Safety and Emergency Function Checks

Where a particular charger includes emergency or other safety-related functions, the manufacturer may specify periodic testing.

For some charging equipment, this may include testing an emergency-stop function and verifying the correct behaviour of the equipment during and after the test.

This should not be turned into a universal procedure for every EV charger.

Testing should follow the instructions for the specific equipment and be carried out under appropriate safety conditions by personnel with the required qualifications and technical access.

Functional Testing

A charger may appear physically intact and communicate with the central system without this automatically proving that the complete charging process works correctly.

Where included in the maintenance procedure, preventive maintenance may therefore include a functional check or test charging session.

This may confirm, for example, that:

• the charger moves through the expected operating states;
• communication with the vehicle works;
• a charging session can start;
• the required functions operate according to configuration;
• the session can end normally.

This illustrates the practical difference between:

“the charger is online”

and

“the charger can actually perform its intended function.”

How Should a Preventive Maintenance Plan Be Defined?

A good preventive maintenance plan does not start with the calendar. It starts with understanding the system.

The operator or maintenance provider needs to know:

• what equipment is installed;
• which models and versions are in use;
• how the electrical architecture is designed;
• how the communications architecture is designed;
• what the manufacturers require;
• what the warranty conditions are;
• how the infrastructure is used;
• under what conditions it operates;
• what problems have occurred previously.

Only then can maintenance activities be organised according to the appropriate intervals and conditions.

Some checks may be calendar-based. Others may depend on component condition, utilisation or a specific event.

This allows preventive maintenance to be planned around the actual equipment, risk and observed condition, rather than treating every asset in exactly the same way.

What Does the Bulgarian Regulatory Framework Mean for Preventive Maintenance?

For charging infrastructure in Bulgaria, it is important to distinguish between requirements relating to the charging equipment itself and rules governing the technical operation of the electrical installations and equipment to which it is connected.

Ordinance No. 16-116 of 8 February 2008 on the Technical Operation of Energy Equipment establishes rules relating to maintaining electrical installations and equipment of electricity consumers in technically sound condition and for their safe operation.

The framework requires technical operation to take account of applicable regulatory requirements as well as manufacturers' technical documentation.

This matters for EV charging infrastructure because the required technical control should not be determined solely by a generic rule or by the commercial label “EV charger”. The specific electrical installation, protective devices, project design, technical documentation and operating conditions all matter.

The regulatory framework should therefore not be reduced to a claim that every EV charger in Bulgaria is subject to the same mandatory annual preventive-maintenance visit.

For a specific site, the necessary inspections and their frequency should be determined according to its actual technical configuration and the requirements that apply to it.

When Should Preventive Maintenance Lead to Corrective Action?

A preventive inspection does not necessarily end with a box marked “checked”.

If a problem is identified, the next action needs to be determined.

Depending on the finding, this may involve:

• continued monitoring;
• additional diagnostics;
• adjustment or configuration correction;
• cleaning or another maintenance activity;
• repair;
• component replacement;
• temporary restriction of use;
• taking the affected charging point out of service until the issue is resolved.

Not every deviation has the same level of criticality.

The result of preventive maintenance should therefore be a technical assessment and a clear next action, rather than simply a list of checks that were completed.

Why Documentation Is Part of Preventive Maintenance

If the information from every preventive-maintenance visit remains only in the technician's memory, part of the value of the work is lost.

Documentation makes it possible to track:

• what was inspected;
• what was identified;
• what measurements or tests were performed;
• what actions were taken;
• which defects remain unresolved;
• which components were replaced;
• whether problems are recurring;
• what recommendations were made;
• what the next planned activity is.

Over time, this history makes trends visible.

If the same connector, communications module or another component repeatedly causes problems, individual service cases can be considered as part of a wider technical pattern.

Preventive maintenance then evolves from “we inspected the charger” into managing the technical condition of the charging infrastructure.

What Is the Role of Remote Monitoring?

Preventive maintenance does not take place only during a technician's site visit.

With connected charging infrastructure, monitoring between scheduled inspections can provide information about changes in system behaviour.

Recurring faults, communication interruptions or other operational deviations may justify earlier diagnostics rather than waiting for the next calendar-based inspection.

This means calendar-based maintenance can be supplemented by condition-based maintenance — technical action triggered by an observed condition or deviation rather than solely by elapsed time.

This does not replace physical inspections. It provides another source of information for deciding when and where technical intervention is required.

How Does Preventive Maintenance Affect Uptime?

Preventive maintenance cannot guarantee that EV charging infrastructure will never experience a fault.

It can, however, help identify some developing problems earlier and reduce the risk that they lead to unplanned unavailability.

The relationship with uptime is not:

“we perform preventive maintenance → failures do not happen.”

A more accurate sequence is:

monitor condition → identify deviations → assess risk → take action → reduce the likelihood that certain issues result in unplanned downtime.

Preventive maintenance is therefore only one part of operational reliability.

Other factors include monitoring, diagnostics, technical competence, incident-response organisation, access to the required spare parts and the ability to restore the system after a fault occurs.

Preventive Maintenance Is Part of the Lifecycle, Not an Isolated Visit

Preventive maintenance provides the least value when it is treated as an isolated visit performed at a fixed interval.

It becomes more useful when every inspection builds on the information from previous ones:

what was the condition → what has changed → what problems occurred → what needs to happen next.

Preventive maintenance then becomes part of the wider management of the charging infrastructure.

This is also the logic behind Qerra Care: preventive maintenance is connected with monitoring, diagnostics, technical response and system history within the agreed scope of service.

Where Qerra has also been involved in designing and building the charging infrastructure, maintenance begins with additional context — project documentation, electrical architecture, installed equipment and integration logic.

Where the infrastructure was installed by another contractor, the first step is a preliminary technical assessment and definition of the scope that can be taken over.

What Should You Receive After Preventive Maintenance?

Well-organised preventive maintenance should leave behind more than confirmation that a technician visited the site.

Depending on the agreed scope, the outcome should provide a clear picture of:

• what was inspected;
• the current technical condition;
• what deviations were identified;
• which findings require action;
• which actions were completed;
• which repairs or additional activities are recommended;
• whether there are restrictions on normal or safe operation;
• what needs to be monitored;
• what the next planned step is.

The real value of preventive maintenance is not the number of boxes ticked on a checklist, but whether the technical condition of the system is better understood and the next actions are clear.

Do You Have EV Charging Infrastructure Without a Structured Preventive Maintenance Plan?

If the chargers are already in operation but there is no clearly defined preventive maintenance plan, the first step is to establish the installed equipment, its technical condition, manufacturer requirements and operating conditions.

Qerra can perform a preliminary technical assessment of existing EV charging infrastructure and define the scope that can be taken over for ongoing technical maintenance through Qerra Care.

Frequently Asked Questions