Ford increased the van's battery monitoring function by 50 percent. Any abnormality causes the electronic software to issue a 'freeze' command and shut down battery operation.
The company is still investigating the cause of two freeze incidents recorded in late November. Twelve customers in the United States and Canada are driving 34 Ecostar vans powered by sodium sulfur batteries. By early 1995, 76 units are expected to be in operation. Five vans arrived in England, Spain and Germany in December. Current electric van users average 500 to 600 miles weekly.
'If we detect even the slight possibility that a battery is malfunctioning, we are shutting the battery down,' said Mike McCabe, Ford Motor Co. sales and marketing manager for electric vehicles. 'We've swung the pendulum so far that we are overprotecting.'
The broadened monitoring function checks three crucial battery operations: current flow, voltage and temperature. Any variance during the constant sweep will trigger a freeze command.
Electric vehicles are a work-in-progress, and vehicles such as the Ecostar are pioneering technology. Automakers who sell more than 35,000 units a year in California are racing to meet the state's mandate that 2 percent of 1998 sales be electric vehicles.
Ford pulled the Ecostar off the road after battery fires in May and June hit two of 34 vans in use. Ford now says the incidents were unrelated. Both occurred during charging.
Ford blames the first fire on rewelding of the battery by the manufacturer. No other units were similarly affected, the company said.
The second fire was the result of a fusing system malfunction. A bypass loop designed to reroute current if necessary overheated and damaged the battery.
Ford broadened the electronic monitoring of the battery in response to the fires. The Ecostar was back on the road Oct. 24.