EV Charger Uptime, SLA and After-Sales: What Buyers Should Put in the Contract

Illustrative image for editorial use. Not a real SINELINK customer project.

1. Define three operating states instead of one uptime percentage

2. The measurement method matters more than the headline target

• Define the denominator: calendar time, service hours, connector-hours, charger-hours or site-hours.
• Define excluded events: utility outage, planned maintenance, vandalism, vehicle fault, network-provider outage, force majeure.
• Define whether partial power or one failed connector is available, degraded or unavailable.
• Name the source of truth: charger logs, CSMS, third-party monitoring or jointly reconciled data.
• Set the reporting cadence and dispute-resolution method.
• Calculate SLA performance on the same unit that matters commercially: often a charging bay or connector rather than a whole network.

3. Do not copy the UK 99% rule into every contract

The UK Public Charge Point Regulations require charge point operators to meet an annual average reliability requirement of 99% for their network of rapid public charge points. This is a regulatory network-level requirement, not proof that every individual charger or connector will achieve 99% availability.

A private fleet depot, workplace site or another country may use a completely different contractual metric. Treat the UK rule as an example of why measurement definition matters, not as a universal global SLA.

4. A useful SLA has at least six clocks

5. Remote diagnostics can reduce downtime only if the service team can act on the data

Status messages and logs are not the same as operational support. The supplier and CPO need a process for alarm ownership, diagnostics, remote reset, firmware handling, escalation and customer communication.

Remote diagnostics are useful only when the operating team has the tools and authority to act on them. Buyers should first review the available monitoring and remote-management functions. If a fault is caused by site power constraints rather than the charger itself, it is also important to understand how site-level power control should behave. For backend operations, a more detailed comparison of OCPP 1.6J and OCPP 2.0.1 can be added once that page is live.

Open Charge Alliance notes that OCPP 2.0.1 includes device management, monitoring, firmware updates, and security capabilities. Those features can support operations, but they do not replace a staffed service process or an SLA.

6. Spare-parts strategy is part of uptime

• Recommended spare ratio by installed charger population.
• Which parts are field-replaceable and which require specialist repair.
• Local or regional stock for power modules, fans, contactors, screens, payment terminals, connector assemblies and communication parts.
• Hardware-revision control so the spare remains compatible after product changes.
• Firmware compatibility and configuration process after a board/module replacement.
• Emergency freight responsibility and customs/import process for remote markets.
• End-of-life / product-support period and last-buy notification.

A spare-parts plan should follow the actual hardware architecture. For DC systems, buyers should verify which modules can be replaced independently and how redundancy affects recovery time before deciding what to stock locally.

7. Warranty and SLA are not the same thing

8. Put FAT, SAT and handover evidence into the service plan

• FAT: verify ordered model, firmware, power outputs, fault logging and recovery behavior before shipment.
• SAT: verify installation, network connection, backend, payment, remote monitoring and representative charging sessions on site.
• Handover: record serial numbers, firmware versions, certificates, configuration backups, contact list and spare inventory.
• Training: define who is allowed to perform first-line resets, part replacement and safety isolation.
• Acceptance: state which unresolved defects block final acceptance and which can be closed under a punch list.

Destination-market conformity should be frozen before this stage using EV Charger Certifications.

9. Build an escalation ladder before the first outage

10. Contract clauses buyers should negotiate

• Availability definition and measurement formula.
• Minimum service level for a connector to count as available.
• Acknowledgement, remote-triage and field-response times.
• MTTR or restoration target by fault severity.
• 24/7 versus business-hours support window.
• Local/remote spare-parts commitments and replenishment time.
• Firmware-update, rollback and cybersecurity-support process.
• Preventive-maintenance scope and frequency.
• Reporting cadence, root-cause report timing and repeat-failure escalation.
• Warranty labor/travel/freight responsibilities.
• Service credits or other contractual consequences for repeated SLA misses.
• Product-support period and end-of-life notification.

11. Uptime also belongs in the business case

Every unavailable connector can reduce delivered kWh, create queues, damage driver trust and increase support cost. For revenue-critical public charging, reliability therefore belongs in the financial model, not only the technical specification.

Link future commercial follow-ups here:  EV Charging Station Cost, EV Charging Station ROI and EV Charging Demand Charges].

12. What to send SINELINK before negotiating after-sales scope

• Country, charger models, quantity and site count.
• Public, fleet, workplace or private-use operating model.
• Required service hours and revenue-critical bays.
• Target availability definition and reporting cadence.
• Local technician capability and desired supplier support level.
• Spare-parts stocking location and customs/logistics constraints.
• Backend/OCPP environment and remote-access rules.
• Required FAT/SAT, training, warranty and escalation terms.
• Expected operating temperature, altitude, dust/humidity and other site stresses.
• Project rollout schedule and expansion plan.

Before requesting a model-specific service plan, shortlist the relevant charger category and define the operating scenario for the site. That gives the supplier enough context to propose a realistic spare-parts, monitoring and support scope.

Frequently Asked Questions

What does 99% EV charger uptime mean?

It means nothing useful until the contract defines the measurement unit, denominator, exclusions, degraded operation and source of truth.

Does the UK require every rapid charger to have 99% uptime?

The UK rule applies as an annual average reliability requirement across an operator's network of rapid public charge points, not as a guarantee for every individual charger.

Is warranty enough for a commercial charging site?

No. Warranty addresses defects and remedies. An SLA addresses response time, restoration, spare parts, reporting and operational accountability.

What is MTTR?

Mean time to repair or restore is a service metric used to measure how quickly equipment returns to service. The contract should define when the clock starts and stops.

Can OCPP improve uptime?

It can support status, diagnostics, firmware and remote management depending on version/profile, but it does not replace spare parts, technicians or a service process.

How many spare power modules should a buyer stock?

There is no universal ratio. It depends on charger population, utilization, site remoteness, module lead time, commonality and acceptable downtime.

What should be tested during SAT?

Network/backend connection, payment where applicable, representative vehicle charging, fault reporting, remote monitoring, safety checks and the agreed site configuration.

What is the most important SLA clause?

A precise availability definition and measurement method. Without it, the headline target is difficult to enforce.