Electric car maker Tesla says it has temporarily increased the battery capacity of some of its cars to help drivers escaping Irma, which hit Florida as a hurricane, but has now weakened to a tropical storm.

The electric car maker said the battery boost was applied to Model S and X cars in the Southeast U.S. Some drivers only buy 60 or 70 kilowatt hours of battery capacity, but a software change will give them access to 75 kilowatt hours of battery life until Saturday. Depending on the model, that could let drivers travel about 64 more kilometres or 40 more miles before they would need to recharge their cars.

Tesla said it made the change after a customer asked the company for help evacuating. The company said it's possible it will make similar changes in response to similar events in the future.