A battery guarantee that holds for the full contract

Fleet charging and energy service providers run the electric side of a bus, coach or truck fleet. They build or operate the depot chargers, manage the energy and often finance the batteries. The vehicle stays with the operator.

The job is to deliver each kWh at the lowest total cost and keep the depot’s peak inside the grid connection. Every bus also has to be charged enough when it leaves.

Why the guarantee lasts longer than the warranty

Providers guarantee battery performance to the bus operator for the length of the contract, often ten years. The manufacturer’s warranty runs five to eight. The gap is on the provider, and the provider cannot measure the pack it guarantees.

Field data from one battery intelligence provider suggests that around 7% of e-buses in public transport fleets carry faults the bus’s own BMS never flags. The depot finds out when the bus does not finish its route, not the evening before.

The battery pack is €140,000 to €175,000 per bus, and the warranty ends years before the contract does. An SoH figure per pack, independent of the manufacturer, is the number behind every capacity guarantee the provider signs.

Buses run for 10 to 20 years and are often owned by the operator, so the State of Health has to last. Even at only 4% degradation a year, a pack is close to useless after 15 years, and sooner after a cold winter. Measuring the SoH is not enough. Health charging reduces the strain on every charge, with up to 14% less degradation over 100,000 km.

In one study of four depots, smart charging cut electricity cost by more than half compared with charging at full power on arrival. Spreading the charging also lowered the grid capacity needed by over 40%. Health charging keeps that saving without paying for it in battery life.