16 BATTERY CHARGING SYSTEMS https://www.mascot.no/ Issue 2 2024 Power Electronics Europe www.power-mag.com Power with purpose: How today’s charging systems are shaping safety-critical design By Dag Pedersen, Marketing Manager, Mascot AS Modern battery charging systems for industrial and medical equipment have evolved far beyond simple power supplies. These vital system components now play a decisive role in determining key design ambitions like safety, reliability and system lifetime, particularly in applications where equipment must operate continuously under demanding conditions and comply with stringent global standards. For engineers developing safety-critical, battery-powered solutions, charger design has become a fundamental system consideration. Be safe, not sorry Safety is the most immediate and prominent area of charger influence. Industrial and medical equipment increasingly relies on battery chemistries with high energy density, especially lithium-ion variants, which provide gains in energy storage but introduce certain challenges without proper management. Overcharging, overheating or cell damage can trigger thermal runaway, making the battery charger the first line of defence against catastrophic failure. Modern chargers serve as active safety systems, monitoring voltage, current and temperature, and responding accordingly. Microprocessor-based control enables chargers to shut down, taper current or adjust charging behaviour upon detecting unsafe conditions, reducing the likelihood of hazardous events like fire. The active safety role extends to multistage charging profiles, particularly for lithium-ion batteries, supporting energy efficiency while avoiding the stress associated with abrupt or uncontrolled charging. In a best-practice example of a multi-step charging profile, stage 1 (boost/constant current) would see the charger operate at maximum current, delivering about 70-80% of the charge; stage 2 (absorption/constant voltage) would involve the charger switching to a lower, constant voltage, topping off the battery (to approximately 85-100%); while in stage 3 (float/maintenance – for Lead Acid and LiFePO4, not Li-Ion), the charger would enter a low-current float charge to keep the battery full without causing damage. Different LED colours typically provide visual indicators of the various stages. In medical environments, the multistage charging approach is reinforced by compliance with strict safety standards that mandate robust protection against electrical and thermal hazards. Industrial systems face parallel challenges, including the need to control hydrogen gas generation in lead-acid batteries or manage heat in high-power installations such as forklifts and automated guided vehicles (AGVs). Conversely, the use of low-quality or non-certified chargers remains a leading cause of battery failure, often resulting in fire risk, hazardous gas release or sudden power loss in safety-critical equipment. Trust the process Beyond safety, charging systems also influence reliability. Modern chargers no longer simply replenish energy; they actively manage battery health to prevent premature degradation and unplanned downtime. Charging algorithms decrease stress on battery cells, while temperature monitoring permits systems to reduce or suspend charging when approaching thermal limits. Automated transition to maintenance/float mode eliminates dependence on operator judgement and prevents damage caused by overcharging or prolonged high-voltage exposure. Chargers increasingly offer diagnostics and data logging, facilitating the adoption of predictive maintenance strategies that identify declining battery health before failures occur. The implications for enhanced reliability extend across both industrial and medical applications. In the latter, the dependable charging of battery-driven equipment such as ventilators, infusion pumps and defibrillators, directly underpins patient safety by ensuring batteries perform as expected during critical or extended procedures. Within industrial environments, automated control reduces manual intervention and protects high-value battery packs. Secrets to long life Total system lifetime is where the cumulative impact of charger design becomes most apparent. Battery lifespan is frequently the restricting factor in the total service life of industrial and medical equipment, with charging behaviour a primary determinant of how rapidly lifespan elapses. Among key factors here is excess heat, which remains one of the most destructive influences on battery chemistry, accelerating ageing and reducing capacity. By dynamically adjusting current, employing pulse-charging techniques and tailoring charging profiles to specific chemistries, modern chargers reduce internal heat generation and slow longterm degradation. Carefully managed charging windows also have a role to play. Maintaining a lithium-ion battery within a moderate stateof-charge range, rather than continually cycling between empty and full, can extend lifecycle. This approach has been shown to double operational battery life in some industrial use cases, while in medical devices it can reduce failure rates and improve availability. Leading the charge At the core of these improvements lie charging algorithms. By managing temperature, voltage and current with greater precision than legacy designs, algorithms mitigate failure mechanisms such as lithium plating during rapid charging and electrolyte breakdown at elevated temperatures. Subtle changes, like limiting peak charge voltage or tapering current more robustly as full capacity approaches, can yield gains in longevity without compromising performance. For lead-acid systems, multistage charging reduces sulphation and electrolyte loss, while lithium-based
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