Following the Unreal Engine 4 C++ BatteryCollector tutorial series is a bit of a hassle because it's made for UE4 ver 4.9. I have successfully followed through the tutorial with ver 4.18, and I'm sharing my code here.
View detailed guide here: http://zslaboratories.com/ue4-batterycollector-c-tutorial-upgrade-from-4-9-to-4-18/