Swift charge

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.