From my understanding the USB chargers just have PCBs that open/close the circuit from a voltage range (4.2v-3.4/3.2/whatever)... very similar to the PCB you find on the 18650 type 'protected' lithium batteries. No actual voltage/current regulation.
I don't have either Husban/Traxxis, but I do have lipo USB chargers for other quads/micro helis. I can measure these ones and report back.
Have you tried charging two dead ones together yet on the Traxxas charger?
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