FEATURE Ernest Davies Award winner are proactively encouraging the use of EVs, which, like a game of hide and seek, are coming, ready or not. No matter what the growth rate of EVs (Tesla alone is planning for half a million per year by 2020) the reality is car parks need to accommodate them, even though the fire risks are not fully known or understood. The burning issue An EV faces the biggest risk of fire from its batteries. Battery technology is improving all the time, with safety systems being added as fast as legislation is brought in to cover the new technologies, and vice versa. Charging controls and battery management systems are becoming more intelligent, the use of better fire-calming chemicals within the battery compartments, including external intumescent barriers designed to resist thermal runaway and isolate the batteries from each other. Battery cooling systems have been installed to attempt to limit the chances of spontaneous ignition of the batteries, which in some cases can occur as low as 66.5C. An example of the lack of general information is exemplified in the way we hear about the causes of thermal runaway, the composition of the batteries and the safety issues they raise. It was not easy to uncover a little-known fact that in some batteries the chemical composition can produce its own oxygen (not to be confused with lithium oxygen batteries) as the chain reaction within the battery proceeds once overheating and burning begins. This will contribute greatly to the problems of extinguishing such fires in battery systems using these chemical combinations, because they cannot be starved of oxygen, which is the main method of extinguishing a fire Other main causes of fire in EVs occur during the charging process. Differing battery configurations require different charging rates. Each We must expect there will be an EV fire event in our car parks and we must be prepared to deal with it when, not if, it happens manufacturer installs systems best suited to their vehicle, all of which require different charging rates and power supply. Battery management is designed to prevent over charging, and some charging points will only allow an 80 per cent charge. If any of these systems fail, the battery pack is at risk of igniting. Unlike the batteries in our laptops and mobile phones, the batteries for EVs should not be rapidly charged too often (only 10 per cent of charges should be rapid), they should not be allowed to be fully discharged, and will function longer if not charged to 100 per cent frequently. If these guidelines are not followed, batteries become compromised, and as in ICE vehicles if the maintenance schedules are not followed the car becomes a higher risk. Firefighting With this bewildering array of facts, figures, science and commercial interests, it is difficult 46 Britishparking.co.uk PNDec18 pp44-47 Ernest Davies.indd 46 26/11/2018 16:28