Swift charge

A battery developed for electric cars can be recharged in minutes

Published: Friday 15 September 1995

No time to lose: recharging el (Credit: USIS)ELECTRIC cars have long been viewed as environment- friendly substitutes to the conventional petrol and diesel driven cars, But one of the main problems confronting the electric car manufacturers is the long time - sometimes as much as 12 hours - that it takes to recharge the vehicles' batteries. Now, a team of Australian researchers say that they have developed a battery that can be recharged at the vehicle service station in minutes (New Scientist, Vol 147, No 1986).

Like conventional batteries, the new device relies on electricity conducting liquid solutions - the electrolytes, bui unlike the former, the latter has 2 electrolytes containing different solutions of vanadium sulpbate and dilute sulphuric acid. The most significant feature of the new battery is that when the solutions are spent, they can be pumped out and replaced, which requires just a few minutes. They can be charged and made ready for the next driver who needs to fill up.

The power source called a vanadium redox flow battery, has been developed by electrical engineers and electrochemists of the Sydney-based University of New South Wales. It has 2 tanks holding the vanadium solutions which are linked to a group of battery cells by 2 small pumps. The pumps replace extra solutions in the stack, when, for instance, the vehicle needs extra power to accelerate uphill. The designers say that only 5 per cent of the energy from the battery is consumed for powering the pumps.

Maria Skyllas-Kazacos, who heads the research team, says, "We can 46demonstrate that the battery works." The researchers have already developed a golf cart that is driven by the battery. "But at the moment, it is too big to be used in cars. We need to reduce the size of storage tanks holding the electrolyte solutions," Skyllas-Kazacos adds.

The new battery, at the moment, needs 280-litre storage tanks - just apt for a bus or a lorry but too big for a family car, say researchers. The team is working on reducing the tank size by doubling the vanadium concentration in electrolytic solutions. This would provide enough energy to run an efectric vehicle for 160 kin, says Skyllas- Kazacos. Compared to other batteries which heat up when being recharged, the new device is safer as it works on ambient temperatures - the electrolytes act as coolants, she adds. Thailand-based Thai Gypsum Products has already begun trials of the new battery to provide back-up power for solar houses in remote areas.

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