How about this: UNSC implement new-found Forerunner technology into their own vehicles using the Janus Key. Since they have to reverse-engineer the discovered technology, not all of it will be readily accessible right away. One of the newly introduced technologies would be light regeneration. UNSC vehicles can perform self maintenance at increased rates. The storm also gets a hold of this technology due to Dr.Halsey's 'methods' ergo we have a reason for vehicles to do this. it is my understanding that everything in matchmaking has a reason for being the way it is, just like this. you're welcome