If you ever take an electric car for a drive, spare a thought for the high-tech, high-voltage battery under the floor, because prototypes of it will have been subjected to two years of technical tortures before being declared safe for production.
In detail, that battery will have been vibrated, squeezed, pressurised, dropped from a height, over-charged with electricity, frozen, heated, barbecue at 800 deg C and even, god forbid, penetrated.
The fact is that the battery of every EV has to undergo dozens of extreme tests, specified under United Nations Regulations ECE 38.3 and 100.3, before being cleared for production. And there’s an engineering centre of excellence in the UK – at the Millbrook Proving Ground in Bedfordshire – where British expertise and facilities are developing the next generation of batteries exactly to these specifications.
“It’s purely down to safety and the safety case,” said Phil Robertson, Millbrook’s global activity manager of electrification. “Individual cells, modules and packs have to undergo and pass a wide range of abuse tests before they can be signed off for production and sold in a finished car.”
The starting point is the lithium ion cells themselves, officially classified as hazardous goods because of the risk of fire. They have to be tested to ECE R38.3, which declares them safe for transport and day-to-day handling, before the next stage of ECE R100.3, which validates the safety of modules and the packs fitted into cars. These packs are the batteries that manufactures quote in their car specs as 40, 60, 80kWh or whatever.
Generally, tier-one cell chemistry manufacturers do the legwork to validate to ECE R38.3 standard, which includes extreme environmental testing, such as hot/cold cycles over a range of -40deg C to 70deg C to simulate air cargo transportation at altitude (cold) to a hot climate; prolonged vibration over a range of 7Hz to 200Hz over a three hour period; and shock to simulate an accident in transit, with forces ranging from 50g to 150g, such as being dropped off a forklift truck or falling off the top shelf in a warehouse.