Charging specifications are quoted in ways that are technically accurate and practically misleading, and the difference is worth understanding before relying on them.
The charging curve
The single most important thing to know.
A battery does not charge at a constant rate. Power is highest at low state of charge and tapers substantially as the battery fills.
Which means a quoted peak charging power is achieved briefly, near the start, under favourable conditions.
This is why charging times are quoted from ten to eighty percent rather than to a hundred — the final portion takes disproportionately long.
Charging from eighty to a hundred can take as long as from ten to eighty on some vehicles.
Why it tapers
Battery chemistry. Pushing current into a nearly full cell risks lithium plating on the anode, which permanently degrades capacity and can create safety issues.
The management system therefore reduces current as the battery fills, and the taper is a protective measure rather than a limitation of the charger.
Temperature
The second major variable and the one that surprises people.
Batteries charge slowly when cold, because lithium movement through the electrolyte slows and plating risk increases.
Which means arriving at a rapid charger with a cold battery in winter can halve the charging rate.
Vehicles with battery preconditioning warm the pack when a charger is set as a destination, which addresses this substantially and requires using the navigation system for the charger.
Many drivers do not know this feature exists or how to trigger it.
What the charger provides
A charger's rating is a maximum, and delivered power is the lower of what the charger can supply and what the vehicle can accept.
Which means a vehicle limited to a modest rate will charge at that rate on any charger above it, and paying for a faster charger achieves nothing.
Sites also share capacity between bays in some designs, so power falls when adjacent bays are occupied, and this is rarely disclosed.
Home charging
Where most charging actually happens for people with off-street parking.
Slower charging is gentler on the battery, and overnight duration makes speed irrelevant.
Which means the practical experience for those drivers is entirely different from the public charging experience that dominates discussion.
For anyone without off-street parking, the reverse holds, and this is the central equity issue in electric vehicle adoption.
Range figures
Official range figures come from standardised test cycles, which differ between regions and are generally optimistic relative to real-world use.
Real-world range is affected by speed, since aerodynamic drag rises with the square of speed, making motorway driving disproportionately costly.
By temperature, since cabin heating draws directly from the battery, unlike in a combustion vehicle where waste heat is available.
And by terrain and load, as with any vehicle.
Winter motorway driving is the worst combination and can reduce range substantially below the quoted figure.
Battery degradation
Capacity declines over time and with use, and the data now available from large fleets is more reassuring than early expectations.
Typical degradation appears to be modest over the first several years, with rapid early loss then a slower ongoing decline.
Frequent rapid charging, sustained high states of charge and heat all accelerate it, which is why guidance suggests charging to eighty percent for daily use.
Warranties typically guarantee a capacity retention percentage over a period, and those terms are worth reading since they define what counts as failure.
The practical summary
Charge to eighty for daily use, precondition before rapid charging, expect worse figures in winter, and check what rate your vehicle can actually accept before paying for a faster charger.
Payment and access
The practical friction that dominates public charging complaints.
Networks have historically required their own applications or membership cards, which meant carrying several.
Regulation in several jurisdictions now requires contactless card payment on new rapid chargers, which addresses this for new installations.
Roaming arrangements between networks exist with varying coverage and generally at a premium.
Reliability
The other persistent complaint, and it is measurable.
Charger uptime varies substantially between networks and is now reported in some markets.
Arriving at a broken charger with low range is the failure mode that shapes perception of the whole technology, which is why regulators have begun setting uptime requirements.
Vehicle-to-load and vehicle-to-grid
Capabilities that turn the battery into a power source.
Vehicle-to-load powers external equipment from the car and is available on a growing number of models.
Vehicle-to-grid returns power to the network, which requires compatible equipment, a supportive tariff and grid operator agreement.
Trials have shown genuine value where those conditions exist, and availability remains limited.
Connector standards
Largely settled in most regions after a period of competing formats.
Which means adapters are needed less often than a few years ago, and legacy chargers using older standards remain in service.
Checking what a network uses before relying on it is still occasionally necessary, particularly for older vehicles.