Altech Batteries (ASX:ATC) said testing of a 28-year-old Zebra battery, which shares the same electrochemical design as its sodium-nickel-chloride battery technology, exhibited successful activation and showed no degradation in function or capacity despite nearly three decades of dormancy, according to a Friday Australian bourse filing.

The earlier Zebra batteries had an energy capacity of around 100 watt-hour compared to the firm's CERENERGY cells with a capacity of 250 watt-hour. CERENERGY batteries were developed to improve energy capacity and reduce battery costs.

Altech's joint venture partner, Fraunhofer IKTS, conducted an individual cell stress-testing program. The 28-year-old battery is currently undergoing daily charge and discharge cycling at 300 degrees Celsius across a state of charge range from 20% to 80%. The tests confirm the battery's safe operation as well as its consistent performance across the full capacity spectrum.

The filing noted that the CERENERGY batteries remain completely inert and stable at ambient conditions, unlike conventional lithium-ion batteries.

Its shares jumped 5% on market close on Friday.