Let's assume I have a ship with collision detector equipped.

I was wondering whether if you choose to Decloak or Barell roll over an obstacle you have to roll a red die for damage if you choose not to use a charge of your collision detector.

Also, do you loose your evade action if you do not spend your charge and this happens while decloaking a phantom?

You do roll for damage. You lose your free evade from debris due to the stress but not from asteroids.

If you don't use collision detector you don't roll for damage when decloaking or barrel rolling over/onto/through an obstacle because you can't boost or barrel roll over/onto/through an obstacle, the action would instead fail and if the action was part of decloaking the decloaking fails.

TLDR: you don't roll for damage because you can't do it in the first place.

I misread, this answer was me thinking the collision detector was not equipped as opposed to equipped without a charge being used. Never answer rules questions before coffee.

I think you can do it since the first part of the upgrade reads:

"While you boost or barrel roll, you can move through and overlap obstacles.

After you move through or overlap an obstacle, you may spend 1 charge to ignore it's effects until the end of the round."

I think both parts are independent of each other.

9 minutes ago, MockingBird ME said:

If you don't use collision detector you don't roll for damage when decloaking or barrel rolling over/onto/through an obstacle because you can't boost or barrel roll over/onto/through an obstacle, the action would instead fail and if the action was part of decloaking the decloaking fails.

TLDR: you don't roll for damage because you can't do it in the first place.

Incorrect.

CD allows boosting and rolling over obstacles independently of charge spending.

27 minutes ago, MockingBird ME said:

If you don't use collision detector you don't roll for damage when decloaking or barrel rolling over/onto/through an obstacle because you can't boost or barrel roll over/onto/through an obstacle, the action would instead fail and if the action was part of decloaking the decloaking fails.

TLDR: you don't roll for damage because you can't do it in the first place - its not optional.

not true.

collision detector has 2 independent parts.

the first part actually prevents you from failing the boost/barrel roll due to overlapping an obstacle - its not optional:

You are all correct, I misread the original and thought he was asking about if he didn't have a collision detector equipped. Edited the original post to avoid confusion.