Traxxas batteries can be charged on other chargers, you just need adapter. They’re not “smart” in the way the Spektrum ones are. Balance leads are just built into the ID connector, other than that, they’re normal run of the mill batteries. They sell adapters that converted the ID plug to a standard connector and standard balance lead. Like
this. Very common misconception that unfortunately makes people spend money unnecessarily or throw out perfectly good batteries
Spektrum batteries use a circuit board inside the battery and a communication wire from the charger. All balancing is done internally in the battery, which is why it requires a special charger. You can’t defeat this with an adapter.