I was disappointed by the pathetic charger action I was used to see since this game was released. So I gathered all necessary cvars and after many mishaps and trials/errors it finally works:
Simply use these values and watch epic survivor bowling^^. The biggest fun is watching yourself flying up HIGH in the air for seconds and falling down after getting hit as a "collateral damage" survivor.
//Charger
sm_cvar z_charger_pound_dmg 12 //def:15
sm_cvar z_charge_duration 2.0 //def:2.5
sm_cvar z_charge_max_speed 900 //def: 500
sm_cvar z_charge_max_force 1200 //def: 800
sm_cvar z_charge_min_force 800 //def: 550
sm_cvar z_charge_warmup 0.2 //def: 0.5
sm_cvar z_charger_max_prop_force 9000 //def: 3000
sm_cvar z_charge_impact_radius 200 //def: 120
You have to take care that survivors do not die from fall damage as they get thrown extremely far/high, so set this cvar also:
sm_cvar survivor_incap_max_fall_damage 1000 //def: 200 Otherwise players would leave instantly

Have fun!