 General Motors explained the modifications will enhance the vehicle structure that surround the battery and the battery coolant system to improve battery protection after a severe crash . The safety enhancements consist of strengthening an existing portion of the Volt ’ s vehicle safety structure to further protect the battery pack in a severe side collision ; add a sensor in the reservoir of the battery coolant system to monitor coolant levels ; and add a tamper @-@ resistant bracket to the top of the battery coolant reservoir to help prevent potential coolant overfill . The additional side safety structural pieces have a total weight of 2 to 3 lb ( 0 @.@ 91 to 1 @.@ 36 kg ) , and their function is to spread the load of a severe side impact away from the battery pack , reducing the possibility of intrusion into the pack . 
