The dangers of overcharging your EV battery

Authored by Priya Nagra , Strategy Analyst

Operating an electric fleet brings a new set of challenges and responsibilities for businesses, including how to manage EV charging. An overlooked consequence of inadequate EV charge management is overcharging your battery.

Overcharging occurs when an electric vehicle’s battery is charged beyond its maximum recommended capacity. Today’s EVs have battery management systems that are designed to prevent overcharging, which help avert potential safety hazards. However, faulty charging equipment, user error, or simply sub-optimal charging practices could still result in overcharging your EV battery.

What are the dangers of overcharging?

Reduced battery lifespan

Charging practices significantly impact the lifespan of the battery. Consistently charging vehicles to 100% state of charge (SOC), keeping them at a high SOC for long durations, and discharging to low levels can lead to premature degradation and reduced performance. This also applies to excessive fast charging, which accelerates capacity loss. For fleets, this means increased maintenance and battery replacement costs.

Increased safety risk

Charging to a high state of charge and deploying fast chargers generates excess heat within the battery. This increases the risk of an uncontrollable rise in battery temperature, a phenomenon known as thermal runaway, which could lead to battery fires. Such incidents can result in property damage and serious injuries, and whilst this risk is small it is important to take active measures to prevent this occurring. Safety should be a top priority for all fleet managers in the transition to electric.

Inefficiency and downtime

Since overcharging leads to battery capacity degradation, range will also diminish gradually. In the long term, more frequent and extended charging sessions may be required to fulfil operational requirements. More significantly, the increase in battery replacements and repairs required due to overcharging contributes to operational downtime and disruption. This can increase inefficiencies, potentially impact customers, and weigh negatively on the Total Cost of Ownership of an EV fleet, as operating and maintenance becomes more expensive.

How do you prevent overcharging?

Smart charging services

Invest in smart charging services which automatically manage charging to prevent overcharging. EV management systems can optimise charging based on factors such as energy prices and battery health and can alert you to any anomalies to ensure the smooth running of your electric fleet.  

Charging schedules

Setting fixed charging schedules, based on operational needs, can prevent overcharging. This ensures that charging is determined by each vehicle’s schedule and existing state of charge, preventing unnecessary charging and improving efficiency of charging operations.

Regular maintenance

Routine inspection and maintenance of charging infrastructure and vehicles will help prevent any serious issues caused by overcharging. Equipment faults must be identified and addressed early on to avoid safety hazards and prevent operational disruption.   

Education and training

Educating drivers and depot managers on how to identify charging and battery hazards is a critical yet often overlooked solution to prevent overcharging. Companies which fail to consider the operational changes and new skills required to run an EV fleet will experience more downtime, greater charging issues and a significantly higher battery failure risk.

Hitachi ZeroCarbon optimises charging and battery health for electric fleets

Hitachi ZeroCarbon supports commercial fleets throughout their electrification journey. Our solutions use smart charging controls and advanced analytics to optimise charging operations, protect battery health, and enhance battery life.

We also provide a live dashboard of fleet operations and assets, safety alerts and regular performance reports to empower fleet managers to oversee all operations and improve efficiency.  

We enable businesses to operate safe, reliable, and efficient electric fleets.  

To find out more about our solutions, please get in touch with our team.