Upgrading Whirlwind, Shadow Chain or Reconstruction is essential because it vastly increase zealot’s survivability and killing power. Charge do have synergy with them it should be in the later priority.
Consider this man, spending 100 minerals zealots with far more efficient performance could be best for your overall economy in a game in the long run.
In early game Zealots with better performance can outlast enemies long and safe enough for you to build up on your main death ball.
However with Charge as your first upgrades may prove less effective. While it does empower your zealots but your initial force is more unstable and make you spend more resources just to keep them afloat until you upgrade with later abilities (Whirlwind, Shadow Chain). So in economical sense it isn’t that good either.
And besides spending 50 more resources and 30 seconds upgrade time is a fair trade off.
If you are well off with upgrading to charge ability first, then that’s fine.
But based on our experience, we strongly recommend to upgrade more powerful abilities before charge.
And since you are writing this in the brutation Page, I even more strongly recommend the above.