Why do chargers fail, and how are they maintained?
Charger 2 has its new power module. The technician restarts it, and minutes later the operator's backend shows it at full power again.
Its outage, at reduced power, lasted about twelve hours.
The questionWhy do chargers fail, and how is being available measured?
of outage per year at most
of outage per year at most
of outage per year at most
of outage per year at most
Computed. In the UK, an operator's network of rapid charge points, 50 kW and more, must be reliable for 99% of the time on average over each calendar year.
What counts as up
sounds simple, but the definition decides the number. The UK rules count a rapid charge point as reliable while its reported status is available, charging or reserved; unknown or blocked are left out of the measurement, inoperative or out of order count against it. Where a point is open only at certain hours, only those hours count.
In the EU, requires operators to publish for every public point whether it is operational or out of order.
Five kinds of outage
- Hardware. , fans and carry high power or move, and wear over time. Modular designs limit the effect of one failure.
- Connection. Without its backend, a charger cannot check most cards. lets a charger keep a local list of cards and a cache of earlier verdicts to bridge such gaps.
- Software. Errors after an update, or a charger that needs a restart. Remote updates and restarts can solve them.
- Car side. Car and charger disagree during the start; the cause can sit in either one.
- Damage. Driven-over cables, broken connectors, cut cables.
Maintenance from a distance
- Remote first. Through its digital connection, the charger reports faults; the operator can read logs, restart and update it remotely.
- Modular repair. Power modules, fans and cables are exchanged as units, which keeps visits short.
- Preventive checks. Filters, fans, coolant, connector wear and the condition of the cable are inspected at fixed intervals.
Why a session fails from the driver's point of view is the subject of EV charging fundamentals, stop 06.
Check your understanding
3 questions. Answer all of them to complete this stop. Each answer explains itself.
How long may a charging port be out at most in a year at 97% uptime?
3% of 525,600 minutes is 15,768 minutes, about 11 days.
Under the UK rules, which reported status counts against a rapid charge point's reliability?
Available, charging and reserved count as reliable; unknown and blocked are left out; inoperative and out of order count against it.
What does AFIR require operators to publish about every public charge point?
Operational status is part of the dynamic data under Article 20, together with availability and the ad hoc price.
- OCPP Open Charge Point Protocol: the open protocol between a charger and its operator's backend. EV charging fundamentals, stop 03 Glossary
- Uptime The share of time a charger was technically able to charge. EV charging fundamentals, stop 06 Glossary
- AFIR Alternative Fuels Infrastructure Regulation (EU) 2023/1804: EU rules for public charging, from payment to coverage. EV charging fundamentals, stop 08 Glossary
- Power module One of several identical conversion units in a DC charger; together they set its power, and each can be exchanged as a unit. Stop 04 Glossary
- Contactor An electrically operated switch for high currents; in a DC charger it connects the output to the car only after both have checked the connection and matched the voltage. EV charging fundamentals, stop 04 Glossary
- legislation.gov.uk: The Public Charge Point Regulations 2023 (SI 2023/1168), regulation 7: 99% reliability of rapid charge points and how it is measured. https://www.legislation.gov.uk/uksi/2023/1168/made. Checked 13 Oct 2026.
- legislation.gov.uk: The Public Charge Point Regulations 2023 (SI 2023/1168), regulation 7: 99% reliability of rapid charge points and how it is measured. https://www.legislation.gov.uk/uksi/2023/1168/made. Checked 13 Oct 2026.
- EUR-Lex: Regulation (EU) 2023/1804 (AFIR), Articles 2, 5 and 20 and Annex II. https://eur-lex.europa.eu/eli/reg/2023/1804/oj. Checked 09 Oct 2026. © European Union, reused under Commission Decision 2011/833/EU.
- Open Charge Alliance: OCPP 1.6 edition 2 (2017), section 3.5 Local Authorization List and Authorization Cache; free download. https://openchargealliance.org/download-ocpp/. Checked 13 Oct 2026.