Law officers in west Alabama say they found more than 12 kilograms of heroin hidden inside Duralast vehicle batteries.

A Texas man was charged with possession of heroin with intent to distribute after he was pulled over Feb. 10, Al.com reported.

Drug task force agents stopped the man’s vehicle on Interstate 20/59 in Greene County for speeding and following to closely, federal court records show.

Homeland Security Investigations Special Agent Quinn Harris said the man gave them permission to search the vehicle, and officers spotted three spare batteries in the rear of the vehicle.

Officers used a portable X-Ray machine to scan the batteries and found anomalies inside, Harris said.

Batteries are commonly used to smuggle drugs in the U.S., authorities said.