Vehicle Battery

A vehicle battery stores the electrical energy a vehicle needs. Every car and van has a 12 V battery that starts the engine and powers on-board electronics; electric and plug-in hybrid vehicles also carry a much larger traction battery that drives the motor. For a fleet, both affect availability, running costs and resale value.

Two batteries, two roles

• The 12 V battery (lead-acid or AGM on most combustion vehicles) supplies the starter, lights, locks, infotainment and any telematics unit. On electric vehicles it still powers the low-voltage systems and wakes up the car. A weak 12 V battery is one of the most common reasons a vehicle will not start in the morning.
• The traction battery (almost always lithium-ion) stores the energy that moves an electric vehicle. Its capacity, in kilowatt-hours, sets the electric vehicle range, and a battery management system (BMS) watches the temperature and voltage of each module.

State of charge and state of health

Two indicators describe a traction battery:

• State of charge (SoC): how full the battery is right now, the EV equivalent of a fuel gauge.
• State of health (SoH): how much of its original capacity the battery still holds. A falling SoH means fewer kilometres per charge, not a sudden failure.

Batteries age in two ways: with time (calendar ageing) and with use (cycle ageing). Heat, long periods parked at very high or very low charge, and frequent rapid charging speed up both. The 12 V battery suffers mainly from short trips, long periods without use and accessories drawing power while parked.

Why it matters for a business fleet

• Availability: a flat 12 V battery grounds a vehicle for the day, and a traction battery that has lost capacity may no longer cover a given round.
• Total cost: the traction battery is the most expensive component of an electric vehicle, and its health weighs on residual value at lease return or resale.
• Allocation: matching vehicles with weaker batteries to shorter routes keeps them productive for longer.
• Charging policy: favouring slow charging at the depot or at home, and keeping rapid charging for long trips, protects the batteries of the whole fleet.

Battery checks belong in wider vehicle health monitoring, alongside fault codes and service due dates.

How Dadycar helps

Dadycar, a French fleet management software, brings battery-related tasks into the same place as the rest of the fleet. The EV optimisation module centralises the charging status of electric vehicles and their charging sessions. Reminders and due dates schedule battery checks and services with a named owner, and alerts flag vehicles that need attention. Telematics, without a box on compatible connected vehicles, adds real mileage and usage data. Data is hosted in France, with OVHcloud.

FAQ

How long does an electric car battery last?
It depends mainly on use, temperature and charging habits. State of health is a better guide than age; our article on the battery life of an electric car explains the factors involved.

Do electric vehicles still have a 12 V battery?
Yes. It powers the low-voltage electronics and wakes up the vehicle, so a flat 12 V battery can immobilise an EV even with a charged traction battery.

How can a fleet manager track battery condition?
By centralising charging data, scheduled battery checks and driver reports for every vehicle, rather than discovering a problem when a vehicle fails to start or runs short of range.