I am considering getting my first electric vehicle (EV). Are charging stations car-specific or usable by all brands? Do high-powered chargers pose greater safety risks?

EVs sold in Singapore use a standardised charging plug known as Type 2, so they can be charged at any charger here.

Modern EVs have a sophisticated and complex on-board controller called the Battery Management System (BMS). It monitors and controls parameters such as temperature, current, voltage and state of charge. The system also maintains the charge-balance of the several thousand individual cells in the total battery pack.

There is no danger in plugging into any station, regardless of the stated supply-power output, whether it is a 7.4kW, 22kW or fast-charging 150kW. However, it does not mean that the EV will receive the stated power. Instead, how quickly it charges is limited by the rating of the vehicle’s on-board charger.

For example, an EV with an 11kW on-board charger will take only up to that charging rate, even if the wall charger it is plugged into can supply at a rate of up to 22kW. The same limitations apply to the fast charging and DC-charging capabilities of the EV’s on-board charger.

The BMS ensures safety in plugging into an EV to any AC or DC charging station.

However, it is best to avoid using a portable three-pin 240V AC charger. If plugged to a wall socket at home, such chargers will draw the maximum current available and usually for longer periods than typical home appliances.

For comparison, a 1.5kW washing machine will draw 6.5 amperes for around two hours each time. A portable EV charger will draw between 10 and 15 amperes for four to five hours. Domestic electricals are not designed for continuous maximum current for extended periods.

The risk of fire from overheated cables is undoubtedly much higher with older houses and buildings, where the insulation resistance would have deteriorated over the years. Even in new developments, the basic household electrical network is not able to detect extreme heat due to unusual extended current flow.

The conductor part of the socket terminal undergoes fatigue with age and the copper strands can break. If there are too few strands remaining to carry the current, it may lead to heat building up. The circuit breaker does not trip because there is no short and the current stays within the limit.

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