Safety Features of a 48V20A Golf Cart Battery Charger for Lithium Batteries

High temperatures in summer may have higher safety requirements for charging. The temperature of the battery and charger determines whether the batteries can be charged safely or not. The temperature also affects the battery capacity. If the battery is charged at excessively high temperatures, it can be damaged and lose its capacity. To protect the battery from damage caused by overcharging, manufacturers have to provide special features on their chargers. These features include the following:

Charger Over Temperature Protection

Batteries can be charged safely if their overtemperature protection circuits prevent the batteries from getting too hot while charging. When the temperature of a battery rises above a certain threshold, a fuse opens and cuts off the charging current. This is a reliable way to prevent overcharging and protect the battery from exploding. Many lithium batteries have built-in thermistors that can detect the internal overtemperature condition of a battery and send an alarm signal to the charger.

Battery Overtemperature Protection

Most lithium batteries can withstand some use up to 130degF but any sustained use above that can damage the battery and shorten its lifespan. Overheating in extreme temperatures can cause thermal runaway that can lead to the battery combusting or exploding. Overtemperature protection circuits monitor battery temperature and shut down the charging voltage when the battery reaches unsafe temperatures.

Many people are unaware that consumer-grade Lithium batteries should never be charged below 0degC / 32degF. When they are charged below freezing, a chemical reaction takes place that leads to plating of metallic lithium on the anode. This leads to a permanent reduction in battery performance and safety. Advanced chargers prevent battery charging below freezing to avoid this issue.

Battery Overtemperature Protection Circuits

Most battery-powered portable devices have a built-in BMS that can sense when the battery is overcharged or overheated and protect it from damage. However, external chargers are often not equipped with this feature. This is where a dedicated BMS and battery-charger solution that comply with JEITA guidelines can be advantageous for designers.

BMSs can be integrated into battery-chargers to provide a complete solution that ensures safe operation for portable devices with Lithium batteries. The integrated solution also includes an Air cooling fan that helps keep the battery cool during the charging process.

The integrated battery-charger and BMS solution can be complemented by an external thermistor to improve the temperature sensing capabilities of the system. The Bourns P-TCO model series of resettable thermal cutoff devices is a good choice for this purpose. This series of highly optimized resettable thermal sensors offers ultra-low resistance and is designed for a wide range of overtemperature and overcurrent protection applications. In addition, they offer a convenient and easy-to-use plug-and-play design and support USB Type-C connectors for charging cables. This can reduce the total cost of ownership of a battery-charger solution while improving its reliability and safety.