Electric car maker Tesla is defending claims its cars become immobilised if the battery ever becomes completely discharged. This results in a battery replacement cost of about one-fifth the car’s $206,000 sticker price.

Tesla owners in the US who have parked their vehicles with low battery power remaining – for as little as a week – have found their cars had become “bricks” that could not be re-charged.

Tesla Australia national sales and marketing manager Jay McCormack said the battery maintenance was explained as part of the company’s customer handover and the car emitted a number of warnings about requiring recharging.

“We explain through our customer ownership experience the recommendations for maintaining the battery,” he said.

“Like all cars, they require some level of care – for us, electric vehicles should be plugged in and charging when not in use, that’s for maximum performance and all batteries are subject damage when at low levels for a long period of time, anything longer than a week for a charge to be kept at zero.”

While there is only one EV on sale in Australia at the moment, Mitsubishi’s tiny i-Miev, several new models arrive this year, a trickle that will soon become a steady flow.

The i-MiEV and it is covered by the company’s 10 year or 100,000km powertrain warranty but what the company calls “the Main Power (Traction) Battery” is only covered for five years or 100,000km.

Mitsubishi’s EV product manager Ashley Sanders said the i MiEV would be unlikely to experience the Tesla’s problems.

“We’ve got a fundamentally-different design to the Tesla, our understanding is that they don’t have the same 12-volt system as we do in our car, with our car all the ancillary devices from the 12-volt battery.”

“As far as the main traction battery goes, in terms of the lithium-ion batteries if you let it go completely to zero it becomes a brick effectively, we have systems in place that doesn’t allow that to happen, except in really long time periods, years rather than weeks or months,” he said.

‘Sequence of warnings’

Nissan’s Leaf electric vehicle has a clause within its US warranty that details what is not covered – damage or failures resulting from “leaving your vehicle for over 14 days where the lithium-ion battery reaches a zero or near-zero state of charge.”

Nissan Australia spokesman Jeff Fisher said there had been no experiences of battery problems with the Leaf.

“We had a situation where the 12-volt battery went down and the lithium-ion battery was low, we replaced the 12-volt and it brought the system back on-line,” he said.

“There are a sequence of warnings before the main drive battery gets too low, then it goes into limp-home mode, you have to be pretty careless to get into that situation – the production cars will have a series of warnings as well,” he said.

Holden’s incoming Volt uses a battery-powered electric motor to drive the wheels but has a petrol engine on board purely capable of charging the battery and extending the range.
Holden spokesperson Emily Perry said the Volt’s drivetrain will not suffer from such an issue.

“The battery has a buffer at the lower end of the state of charge to prevent it ever being fully discharged,” she said.

In the US Tesla has countered that “all automobiles require some level of owner care.”

The all-electric car company also said its cars had low-charge (below five per cent) warnings but that electric vehicles should be plugged in and charging when not in use for maximum performance.

“Tesla batteries can remain unplugged for weeks (even months), without reaching zero state of charge,” the company said in a statement.