I know this post is dead since 2016 but its still one of the first search results for people trying to charge flux-infused weapons / tools on (for example) Tekkit Legends.
So here is what worked for me:
-Source of RF
-RF Consumer (from Power Converters 3)
-Energy Bridge (from Power Converters 3)
-Universal Charger (from Power Converters 3)
Connect your RF source to the RF consumer and place the energy bridge next to the consumer. Now place the universal charger next to the energy bridge.
The universal charger has an inventory in which you can charge the items. Adjacent chests will also charge items stored inside them. Standing on the charger
charges items in your inventory.
Obviously you can also do this with an EU source and an EU consumer (from Power Converters 3) instead if you dont have a reliable RF source.
DON'T FORGET THE ENERGY BRIDGE!!! Charger wont work otherwise.
-Trespassing Problem Solver