102 questions

Questions

Short answers to common questions about eMobility, each with the stop that explains it in full.

EV charging fundamentals

26 questions

  1. Why does charging involve so many companies?Three things spread the work: the grid connection, the location where people park, and contracts that work across many networks. One company can hold several roles, but the roles stay separate.
  2. How many public charge points are there in Europe?More than 1.1 million in the EU alone: the European Alternative Fuels Observatory counted 1,159,838 public recharging points in August 2026. The map on this site covers part of the network: 839,000 public charge points at 227,000 sites across Europe, from national registries and OpenChargeMap.
  3. Who is the CPO and who is the eMSP?The CPO operates the charger and keeps it available. The eMSP issues the card or app, sets the driver's price and sends the invoice. They are often two different companies.
  4. How many companies operate public chargers?Around 15,500 companies operate public charge points in the directory data. A small number of large networks run most of them, while almost 13,000 run fewer than ten each.
  5. Who connects a charging site to the grid?The grid operator, usually the local distribution system operator. It plans and approves the connection, and its capacity sets what the site can deliver.
  6. What happens when I tap my charging card?The charger asks its operator's backend whether the card may charge. For another company's card, the backend checks it with the roaming partner. The approval usually comes back within two seconds.
  7. What is the difference between OCPP and OCPI?OCPP connects a charger with its own operator's backend. OCPI connects companies, so operators and card providers can exchange card lists, tariffs and session records.
  8. How can my card work at another company's charger?Through roaming: operators and card providers exchange card lists, prices and session records, directly or through a roaming hub, and settle in the background.
  9. What happens in the seconds before charging starts?A safety check with insulation test and connector lock, a negotiation of voltage and current limits, and precharge. Only then does current flow.
  10. Why does charging power drop at 80%?Above roughly 80%, the battery management system lowers the power to protect the cells, so the last 20% take disproportionately long. That is why fast-charging times are usually stated from 10 to 80%.
  11. Why does my car charge below the charger's maximum power?The smallest limit applies: the car's battery, the station's converter or the site's grid connection. Most often the car sets the limit.
  12. Why is charging at home slower than on the motorway?At home, the car's onboard charger converts AC to DC. At a fast charger, the station does this at much higher power, so minutes replace hours.
  13. Are most public chargers fast chargers?No. About three in five public charge points in Europe are AC chargers up to 22 kW. About one in five belongs to a site with 150 kW or more.
  14. Why do drivers pay different prices at the same charger?Each commercial route prices the session differently: a contract with an eMSP, a subscription with a monthly fee, or ad hoc payment at the operator's own price.
  15. Can I charge without a contract?Yes. Since April 2024, every new public charger in the EU must allow ad hoc payment, by card at 50 kW and more. The price is shown before the session starts.
  16. What is a CDR?The charge detail record: the digital receipt of a session with energy, duration and tariff. It travels from the operator to the eMSP and becomes a line on the invoice.
  17. Why does public charging cost more than charging at home?The prices cover different things. A public charger's price includes hardware, grid connection, site, service, payment and a margin; a household tariff pays for energy on an existing connection.
  18. Why does a charger sometimes not start?A session can stop at five points: the vehicle handshake, the charger hardware, the mobile connection, the backend or the authorisation. Many causes can be resolved remotely.
  19. What does uptime mean?Uptime measures whether a charge point was technically able to charge. Session success measures whether individual sessions started and finished. Operators track both.
  20. Who pays for the chargers at a supermarket or service station?In many cases a CPO finances, builds and operates them, and the site host receives rent or a revenue share. Public funding can also contribute.
  21. What decides whether a charging site pays off?Utilisation: sessions and energy per day measured against the fixed costs. Location, roaming reach and availability all feed into it.
  22. Why do hotels install slower chargers?Guests park for hours, so 11 kW AC serves them well, while expensive high-power DC would rarely pay back. The power of a site follows how long people stay.
  23. What is Plug & Charge?With Plug & Charge, based on ISO 15118, the car identifies itself with a certificate when plugged in, so no card or app is needed.
  24. What does AFIR require?Ad hoc payment at new public chargers, price and status information through open interfaces, and charging pools every 60 km along the main European roads, with rising power targets up to 2027.
  25. Why do tenders ask for OCPP certification?Implementations can differ in details such as start-up or error handling. Certification and tests with the actual backend close that gap before a rollout.
  26. What is on a charging receipt?The provider's receipt number and price, the operator's charge point ID, session times and meter readings, the VAT split, the payment terms and the record number the session rests on. The deep dive reads one receipt line by line.

eMobility and EV basics

10 questions

  1. What is the difference between a hybrid and a plug-in hybrid?A hybrid takes all its energy from fuel; its small battery is filled by the engine and by braking. A plug-in hybrid also charges from the grid, so everyday distances can run on electricity.
  2. What is the difference between LFP and NMC batteries?NMC stores more energy per kilogram. LFP contains no cobalt and costs less: in 2025, LFP packs were on average more than 40% cheaper per kWh.
  3. What is the difference between kW and kWh?kWh is an amount of energy, for example what the battery holds. kW is a rate, how fast energy flows; time equals energy divided by power.
  4. Why does range drop on the motorway?Air drag grows with the square of speed, and the power needed with its cube. Above about 100 km/h, it dominates consumption.
  5. Why do electric cars lose range in winter?Heating the cabin takes energy, and a cold battery works less efficiently. In a Norwegian winter test, 23 cars lost 21.7% on average against their WLTP range.
  6. How fast do electric car batteries degrade?About 2.3% a year on average in telematics data from over 22,700 vehicles. Frequent fast charging above 100 kW went with up to 3.0%, mostly AC charging with about 1.5%.
  7. What is battery state of health?State of health compares what the battery holds today with what it held when new. At 94%, a 70 kWh battery holds about 66 kWh.
  8. Where do most electric car drivers charge?Privately, at home or at work: almost 75% of the time worldwide, while public fast chargers cover only about 10%. In Norway around 90% of electric car owners can charge at home, in China about half have a home charger.
  9. Does braking charge the battery?Yes: when the car slows down, the motor works as a generator. It returns part of the energy spent on accelerating or climbing, most on descents and in town.
  10. Why do electric cars make a sound at low speed?EU law requires an acoustic alerting system, AVAS, from start up to about 20 km/h and when reversing, so that pedestrians notice the car.

Charging hardware

6 questions

  1. What is the difference between AC and DC charging?With AC, the car's onboard charger converts the current, which limits power, often to 11 or 22 kW. With DC, the charger carries the converter itself and can deliver far more.
  2. Which connector do public chargers in Europe use?AFIR requires at least Type 2 at public AC points and Combo 2 (CCS) at public DC points. One car inlet takes both: Type 2 above, two DC pins below.
  3. Why do fast chargers have such thick cables?A cable is sized for current, and heat grows with the square of it. At the highest currents, a liquid circuit cools cable and connector so the cable stays manageable.
  4. Why do two cars at one charger get less power?Many chargers divide their power modules between two outlets. A car that is fuller asks for less, so the modules move to the other car.
  5. What does charger uptime mean?Uptime is the share of time a charge point is online, available and delivers energy. At 97%, it may be out for about 11 days a year at most.
  6. Is the energy at a charger measured accurately?Charger metering follows measuring law. From 10 October 2028, EU-wide accuracy classes of 2, 1 or 0.5% apply, measured where the energy passes to the car.

Charging infrastructure

5 questions

  1. How far apart are fast chargers on EU motorways?Along the TEN-T core network, AFIR requires a charging pool at least every 60 km in each direction: 400 kW by the end of 2025, 600 kW by the end of 2027.
  2. Why does a charging hub need its own transformer?A megawatt at 400 V needs about 1,700 A. At medium voltage the current is a fiftieth of that, so large hubs connect there with their own transformer.
  3. What does it take to build a charging hub?A site host, a grid connection, an energy supply contract, a building permit and backend and roaming partners. The grid connection is usually the slowest step.
  4. What is utilisation of a charger?The energy a charger delivers compared with what it could deliver at full power all year. Because most costs are fixed, it decides whether a site pays back.
  5. What is in a grid connection offer?The connection point, the agreed capacity, a one-off contribution and the cable cost, the grid fees with their capacity and energy price, the timeline and the conditions. The deep dive reads a composed offer line by line.

Load management

5 questions

  1. What is load management?Load management keeps many chargers below the limit of one connection by dividing the available power. Cars that stand for hours still get the energy they need.
  2. What is the difference between static and dynamic load management?Static load management gives each charge point a fixed share. Dynamic load management measures the building and gives the chargers whatever room is left at each moment.
  3. Can the grid operator limit my wallbox?In Germany, non-public charge points above 4.2 kW put into operation since 2024 count as controllable devices. The grid operator may reduce them temporarily to prevent overload, but at least 4.2 kW remains.
  4. Why does a single-phase car matter for load management?A single-phase car draws all its current from one phase. Several of them on the same phase can overload it, so sites use phase rotation and count each phase.
  5. What does an OCPP charging profile look like?A SetChargingProfile message with a purpose (ceiling, default or one session), a kind, and a schedule of periods with a limit in amperes per phase or watts. The deep dive reads the profiles of one morning and the meter value that shows the car following.

OCPP in depth

6 questions

  1. Is a CSMS the same as a CPMS?Yes, both name the operator's backend. OCPP 1.6 calls it the Central System, OCPP 2.0.1 and 2.1 the charging station management system (CSMS); CPMS is the common industry term.
  2. What is the difference between OCPP 1.6 and 2.0.1?OCPP 2.0.1 is not backward compatible with 1.6: transactions became configurable and unified, and the device model was added. OCPP 2.1 builds on 2.0.1 and keeps it compatible.
  3. How does a charger connect to the backend?The charger opens a WebSocket to its backend, announces itself and then checks in at a set interval. Commands from the backend travel over the same connection.
  4. How secure is OCPP?OCPP has three security profiles. Profile 2 adds TLS and a backend certificate, profile 3 certificates on both sides; profile 1 is not recommended for the field.
  5. Which OCPP messages make up a charging session?In OCPP 1.6: Authorize, StartTransaction, MeterValues and StopTransaction. In 2.0.1, the transaction messages are events of one type, TransactionEvent.
  6. What does an OCPP message look like?In OCPP 1.6 over JSON, a message is a short array: 2 for a call with an action name and payload, 3 for the result with the same id, 4 for an error. The deep dive reads a whole session of them.

OCPI and roaming

5 questions

  1. What does OCPI exchange?Locations and tariffs from the operator, tokens from the provider before a session; sessions and commands during it; the CDR after it.
  2. What is a roaming hub?A platform that connects many operators and providers through one link each. Many companies use hubs for the long tail and direct OCPI links for large partners.
  3. How is a roaming card authorised?Either from a cached list the provider shared with the operator, or by a real-time check with the provider. The provider sets which, per token.
  4. Can a CDR be changed after it was sent?Not directly. OCPI treats CDRs like invoices: a wrong CDR is cancelled with a credit CDR and replaced by a corrected one.
  5. What is in a CDR?Who wrote it, the token that started it, the one EVSE used, the tariff as it applied, the session as periods with energy and time, and the totals before taxes. The deep dive reads a complete record line by line.

Plug & Charge

5 questions

  1. How does Plug & Charge work?The car carries a contract certificate and presents it to the charger over the cable. The backend checks it, and charging starts without a card or app.
  2. Who issues Plug & Charge certificates?Certificate authorities that operate V2G roots, with trust lists that let several roots work together. CharIN coordinates governance but does not operate a PKI.
  3. Why does Plug & Charge not work at every charger?Car, charger, backend, contract and trust all have to support it. If one is missing, the session starts with a card or app instead.
  4. What is ISO 15118-20?The second generation of ISO 15118, published in 2022. It adds bidirectional power transfer, wireless communication and automatic connection; a 2026 amendment adds megawatt charging and grid services.
  5. What is in a Plug & Charge certificate?A subject with the eMAID, an issuer, a validity period, a public key and the issuer's signature, chained through the provider's sub-CAs to a V2G root the charger trusts. The deep dive prints one chain and the four checks the backend runs on it.

Energy and grid integration

5 questions

  1. Can the grid handle electric cars?Nationally, EVs used about 1% of the world's electricity in 2025. Locally, the issue is timing: spread into the night, most charging fits existing grids.
  2. How green is the electricity for charging?The EU's electricity was 49.9% renewable in 2025. Charging can follow hourly renewable data, drivers can choose green tariffs, and public operators state whether a charger's electricity is 100% renewable.
  3. Is charging cheaper at night?With a dynamic contract, often yes, and also around midday on sunny days. Prices move every quarter hour; a controller can pick the cheapest slots before departure.
  4. Can I charge my car with solar panels?Yes, from the surplus the house does not use. Cars need a minimum of about 1.4 kW on one phase or 4.1 kW on three, so wallboxes that switch phases follow the sun best.
  5. How is a dynamic electricity price made up?The day-ahead price of the quarter hour, plus grid fees, levies and taxes and the supplier's margin, which do not move, plus VAT on the sum. In the deep dive, 7.0 ct wholesale at 2 AM became 27.7 ct retail.

Bidirectional charging

4 questions

  1. What is bidirectional charging?Smart charging in which electricity can also flow from the car's battery back to the charging point, to a device, a house or the grid.
  2. What is the difference between V2H and V2G?V2H powers the house behind its meter; V2G feeds the public grid. V2G brings in generator rules, metering in both directions and the electricity market.
  3. Does V2G damage the battery?It adds energy throughput, typically a fraction of what driving adds, at low power. Fast charging above 100 kW was linked to faster ageing in a large study.
  4. How does a car know when to discharge?It follows the wallbox. After both have selected the bidirectional service and stated their limits, the wallbox drives the current every moment within those limits and reports it; a negative value means out of the car. The deep dive reads one evening of those messages.

Battery storage

4 questions

  1. Why do some fast chargers have a battery?Peaks of demand are short. A battery charges slowly from a small grid connection and discharges quickly into cars, so a site can offer high power where the grid cannot yet.
  2. Are battery storage systems safe?EU law requires stationary systems to be tested for the safety parameters of Annex V of the Batteries Regulation, ten tests from thermal shock to fire, with the emission of gases considered throughout, and to document further hazards and their mitigation.
  3. What is a battery passport?From 18 February 2027, EV batteries and industrial batteries above 2 kWh need an electronic record with information on the model and the individual battery.
  4. How does a site battery plan its day?From a demand forecast, the grid limit and the day's prices, hour by hour, with four rules in order: never below the floor, cover the peak, keep the reserve for the next peak, then follow the price. The deep dive shows one day's plan.

Payments and billing

5 questions

  1. How is a charging price made up?From a price per kWh, per minute, per session and any other component. At 50 kW and above, the ad hoc price is based on kWh, with an optional fee per minute.
  2. Can I pay by bank card at a charger?At public charge points deployed since April 2024, yes: operators must accept card readers, contactless devices or, below 50 kW, internet payment such as a QR code.
  3. Is charging abroad more expensive with my card?Providers must show all price components before a session and may not apply extra charges for cross-border e-roaming in the EU.
  4. What must be on a charging invoice?For VAT: date, sequential number, VAT numbers, names and addresses, quantity, unit price, VAT rate and amount. Session details such as site, times and kWh make it easy to check.
  5. What does a signed meter value look like?An OCMF dataset: a JSON section with the gateway, the meter, how the user was identified and the readings at start and end, followed by the meter's signature. The meter's public key verifies it. The deep dive reads one line by line.

Business models

4 questions

  1. Why is public charging more expensive than home charging?A public charger adds hardware, a grid connection, the site, operation and payment. The IEA reports public fast charging prices up to 240% above residential tariffs.
  2. How do charging companies make money?Operators earn from energy sold ad hoc and through roaming, plus time fees and flexibility; providers from the difference between their prices and operators' tariffs, or subscriptions.
  3. Is a charger profitable?It depends on utilisation: fixed costs are the same whether ten or a hundred cars come, so every extra session lowers the cost of every kWh.
  4. What does a charger's profit and loss statement look like?Revenue by route (ad hoc, roaming, time fees), energy as the one cost per kilowatt-hour, payment and roaming fees, then the fixed lines: depreciation, site, service, software, overhead. The deep dive reads one charger's year line by line.

Regulations and compliance

4 questions

  1. What does AFIR require from charge point operators?Ad hoc payment, transparent prices shown before charging, digital connection, smart recharging at new points, fixed cables at DC points and open data via national access points.
  2. Do new buildings need charging points?Under the recast EPBD, new offices with more than five spaces need a charge point for every two spaces; other new non-residential buildings one in five; new residential buildings pre-cabling for half.
  3. Can my landlord refuse a wallbox?Under the recast EPBD, a request by tenants or co-owners may be refused only on serious and legitimate grounds; the details come through national law.
  4. What does AFIR charge point data look like?AFIR lists the data items, not a format. In practice operators publish an OCPI location record: address, connectors and opening hours as static data, status, the ad hoc tariff and the renewable flag as dynamic data. The deep dive reads one line by line.

Fleet charging

4 questions

  1. How is home charging of a company car reimbursed in Germany?From 2026, the measured kilowatt-hours are reimbursed at the employee's own tariff or at an official flat rate, 34 cents per kWh for 2026; monthly lump sums ended with 2025.
  2. How much power does a depot need?Start from the routes: energy per vehicle and night, divided by the hours available. With load management, the connection can be far below the sum of all chargers.
  3. How do fleets track public charging costs per vehicle?Each public session arrives as a charge detail record that names the token used, with energy, time, place and cost; a token per vehicle or driver links it.
  4. What is in a fleet charging report?Sessions, energy, the peak against the connection limit, the charging window, exceptions, a readiness check from the vehicles' battery data and the energy cost. The deep dive reads one night's report and one home charging statement line by line.

Truck charging

4 questions

  1. How fast can an electric truck charge?The Megawatt Charging System allows up to 1,250 V and 3,000 A; trucks in series production charge at up to about 1,000 kW, from 20% to 80% in about 30 minutes.
  2. Can trucks charge during the driver's break?Yes. After 4.5 hours of driving, the driver must take at least 45 minutes of break; planned at a megawatt charger, it becomes the charging stop.
  3. What does AFIR require for truck charging?Pools for heavy vehicles along the TEN-T network: 1,400 kW along 15% by 2025, 2,800 kW on the core network along 50% by 2027, and 3,600 kW every 60 km by 2030, plus parking areas and urban nodes.
  4. How does a truck charger get reserved?The provider sends an OCPI ReserveNow command with the token, the site, the charger and an expiry time. The operator confirms receipt at once and passes the reservation to the charger; the charger's result follows at a response URL.