Charge batteries with care: 7 tips for maximising the TCO of your electric fleet
Battery lifespan is a crucial TCO lever for any electric fleet. Poor charging habits can significantly reduce capacity and drive operating costs up.
The topic briefly and concisely
Keep the state of charge of your fleet vehicles consistently between 20% and 80% to significantly extend battery life.
Prioritise gentle AC charging at the depot overnight and use DC fast charging only selectively on long-distance journeys.
Avoid charging in extreme temperatures and use sheltered parking spaces to keep the battery within the optimal range of 15–25°C.
The transition to electromobility presents fleet managers with new challenges, particularly in relation to the longevity of vehicle batteries. A degraded battery means not only reduced range, but also significant loss of value and higher total cost of ownership (TCO). A strategic charging approach is therefore essential. With the right methods for battery-friendly charging, you not only safeguard your fleet’s performance, but also more easily comply with the requirements of the Clean Vehicles Directive (CVD). This guide shows you how to optimise the battery health of your commercial vehicles, such as the HEERO D2E (Diesel-to-Electric)-Sprinter with its 110 kWh battery, in a targeted way.
The 20–80% range as the gold standard
The state of charge (SoC) is the most important factor for battery health. Constant charging to 100% or deep discharging below 20% places considerable stress on the battery cells. Studies show that keeping the state of charge within the 20% to 80% window significantly slows calendar and cycle ageing. For day-to-day fleet operation, this typically means a 10-15% longer battery service life. Adhering to this corridor is the single most effective measure for preserving value. Intelligent charging planning that takes the State of Charge into account is therefore essential. Modern battery management systems (BMS) help to maintain these charging limits automatically and protect the investment. This approach ensures that the full range is only called upon when it is needed for a specific route.
AC depot charging as the basis for a long battery life
For daily charging at the depot, AC charging is the gentlest method. Slower charging at lower power, such as 22 kW AC charging on HEERO vehicles, generates significantly less heat and reduces stress on the cell chemistry. DC fast charging with high power, such as the 165 kW in our Diesel-to-Electric (D2E) conversions, is designed for rapid charging on the road to ensure operational readiness. However, frequent DC fast charging can negatively affect battery life. An optimised charging strategy for fleets therefore primarily uses overnight stationary periods for gentle AC charging. The following list shows the typical application:
AC charging (up to 22 kW): Daily overnight charging at the depot for 90% of all assignments.
DC fast charging (from 50 kW): Targeted top-ups on long journeys or when multiple assignments arise unexpectedly.
Charging planning: Plan routes so that DC charging remains the exception, in order to protect the State of Health.
Cost factor: Overnight depot charging is generally around 30% cheaper than public DC charging.
This distinction between AC and DC charging is fundamental to TCO optimisation.
Temperature management to prevent cell damage
Operating temperature has a direct impact on the efficiency and service life of lithium-ion batteries. The ideal temperature range, according to TÜV NORD, is between 15 and 25 degrees Celsius. Both high summer heat and extreme winter cold place strain on the battery. Charging at temperatures above 35°C or below 0°C can lead to irreversible loss of capacity. A sheltered parking space can stabilise the battery temperature by up to 10°C. Fleet operators should therefore take the following measures:
Park vehicles in a garage or under a carport to protect them from direct sunlight and frost.
Charge the vehicle directly after driving, while the battery is still at operating temperature, especially in winter.
Use the vehicle's preconditioning to bring the battery to the optimum temperature before charging.
Avoid rapid charging processes when the battery is very cold or overheated.
An active thermal management system, as fitted in HEERO vehicles, is crucial for long service life.
Optimising charging cycles for maximum durability
The service life of a battery is often measured in charging cycles. One cycle corresponds to a complete discharge and recharge from 0 to 100 %. High-performance lithium-ion batteries can withstand at least 1,000 such full cycles. Charging in smaller partial cycles, for example four times from 50 % to 75 %, is, however, far gentler than a single full cycle. Two charging sessions from 20 % to 70 % place less strain on the battery than one charging session from 0 % to 100 %. For a fleet with an annual mileage of 40,000 km per vehicle, this means that, with proper care, the battery can easily last 8 to 10 years. Intelligent planning of charging sessions, aligned with daily energy requirements instead of generally charging to full as a rule, is the key to maximising cycle durability and therefore extending the vehicle's service life.
Driving behaviour and recuperation as influencing factors
Not only charging, but also driving affects battery health. An anticipatory and smooth driving style is easier on the battery. Hard acceleration and sustained high speeds require high discharge currents, which place considerable strain on the battery cells. The use of regenerative braking, in other words energy recovery when braking, also helps to reduce wear. Efficient regenerative braking can significantly increase range while also reducing wear on the mechanical brakes. Training drivers in the use of electric commercial vehicles is a worthwhile investment. It can reduce energy consumption by an average of 10% and extend battery life. A defensive driving style is therefore a direct contribution to lowering the total cost of ownership of your fleet.
More useful links
The ADAC covers the topic of how to protect the battery of electric cars, especially when charging.
A publication by the Federal Environment Agency provides information on the energy consumption of electric cars.
The Federal Ministry for Economic Affairs offers a dossier on e-mobility.
The NOW GmbH provides a practical guide to e-mobility in fleets.
The Fraunhofer ISI presents market ramp-up scenarios for electric vehicles.
The dena (German Energy Agency) offers a dossier on expanding the charging infrastructure for electric lorries.
The National Contact Point for Commercial Vehicles covers topics relating to commercial vehicles.
Agora Verkehrswende publishes a BCG study on the 15-million target for electric cars in China.
The BMV (Federal Ministry for Transport) presents the Charging Infrastructure Master Plan 2.
FAQ
Why is charging to only 80% better for the battery?
Charging to 100% creates high voltage and temperature in the battery cells, which accelerates chemical ageing. By limiting the charge to 80%, you significantly reduce this stress and can extend the battery’s cycle life by many hundreds of charging cycles, which directly lowers the TCO.
Is frequent DC fast charging really harmful to my fleet's batteries?
While modern battery management systems minimise the risks, the high current during DC charging inevitably leads to more heat and stress on the battery. For occasional use, it is harmless, but as a daily charging method it can accelerate degradation. As a rule, the basis should be gentle AC charging at the depot.
How does cold affect charging my electric fleet in winter?
At low temperatures, the electrochemical processes in the battery slow down. Charging a cold battery, especially at high power, can cause damage. It is therefore advisable to charge the vehicle immediately after a journey, while the battery is still warm, or to use preconditioning.
What charging power is ideal for overnight depot charging?
An AC charging capacity of 11 kW or 22 kW is ideal for overnight charging. This output is sufficient to bring the vehicles to the desired state of charge of 80% over several hours, gently and in full, without overloading the depot’s power grid or placing strain on the batteries.
Does HEERO offer solutions for monitoring battery health?
Yes, our vehicles are equipped with advanced battery management systems (BMS) that continuously monitor the condition of the battery. As part of our depot charging consultancy and fleet analysis, we also offer concepts for intelligent load and charging management that optimise the battery health of your entire fleet.
Won't I lose too much range in everyday use because of the 80% rule?
For most daily routes in urban delivery transport or municipal operations, 80% of the range is perfectly sufficient. A HEERO D2E Sprinter offers a typical range of over 300 km even at 80% charge. The full range of up to 425 km is only needed for planned long-distance journeys and can then be charged specifically when required.
