Crate engines are an American tradition, beloved of racers and hot-rod builders and accurately named, as that’s exactly what they are: complete engines delivered to your door in a wooden crate.
In recent years, Swindon Powertrain has taken a similar approach to off-the-shelf EV powertrains. Smaller companies wanting to produce niche vehicles or just get started in the EV market can buy Swindon’s ‘crate’ e-drivetrains and e-transmissions. And now there are battery solutions to go with them.
Swindon’s energy-dense packs are aimed at light-duty vehicles of up to 3500kg, meaning cars, vans and LCVs. They come in two sizes, 30kWh and 60kWh, the latter of which should make it possible to build low-volume EVs with meaningful range.
Continuous power output is 31kW for the smaller pack and 61kW for the larger one, and both are liquid-cooled by a 50:50 mixture of glycol (anti-freeze) and water.
Technically, they’re straightforward, automotive-standard, lithium ion units measuring 1000mm long and 420mm wide and either 375mm or 615mm high, depending on the capacity. Weight is just 190kg for the smaller pack and 350kg for the larger one, including the integral battery management system and a manual disconnect for servicing or emergencies. The packs are supplied in their own enclosures (cases), which incorporate thermal management and prevent physical damage.
Elsewhere in the battery industry, American firm Nextech’s lithium-sulphur technology has earned the latest safety certification needed for it to be used in production. Nextech says this is the first battery of its type to earn the certifi cation and explains the advantages of its “semisolid-state” chemistry is that it doesn’t have potential for thermal runaway or contain oxygen-producing combustible materials.
Thermal runaway is the potential that any lithium ion battery has to burn uncontrollably if control of it is lost. In production EV batteries today, thermal runaway is prevented by the battery management system, which carefully monitors the charge and discharge state of cells, the load being put on them and the internal temperatures of the battery.
The kind of tests that EV batteries are subjected to should allay the fears of anyone still concerned about their safety. The tests passed by the Nextech battery (which go by the catchy moniker DOT UN 38.3.5) include altitude tests to ensure it won’t swell and fail at low atmospheric pressure; thermal tests to check its robustness in the face of rapid and extreme temperature changes; and tests of vibration, shock, external short circuit (what happens if anything that the battery is connected to is short-circuited), crush, impact and forced discharge. The last of these evaluates how well a cell can withstand being ‘force discharged’ (which means discharged too much) without suffering severe damage.
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