 Despite containing near identical energy ( + / - 0 @.@ 5 kWh ) , the Volt 's battery pack is over 70 % lighter than the EV1 's original 1 @,@ 310 lb ( 590 kg ) , 16 @.@ 5 kWh AC Delco lead @-@ acid battery pack , mainly because the Volt uses higher specific energy Li @-@ ion batteries . Li @-@ ion batteries are expected to become less expensive as economies of scale take effect . 
