Scientists have designed an accurate battery metre for electric vehicles, which they claim can prevent drivers running out of charge and coming to a standstill at inappropriate times.

A team at Waikato University, led by Philip Rowe, has come up with the intelligent battery metre by using three different methods at the same time - a working model has been installed and tested on a motor scooter already.

"We wanted to develop a metre that worked more like a petrol gauge on any lead acid battery. The idea is that the metre gets to 'understand' the battery so it can give an accurate indication of how much power remains.

"We combined three different measuring methods found they complemented each other and by switching between them we could get a meaningful read out," Rowe said.

According to team member Prof Jonathan Scott, battery metres have been a weak point in the world of electric cars for many years. "So much so, people are sceptical about our claim to have a practical, workable solution to the problem. It's time for this technology to cross the divide into the commercial arena, with serious investment and rigorous testing," he said. The scientists say that the metre could also be manufactured for common use and it has potential to be used in golf carts, mobility scooters and other electric vehicles. "It offers a huge variety of different areas to work in - and there's a great sense of achievement in developing something that is practical and useful," Rowe said.