Penance Brand (of Dissipation) - energy reset?

Hi
quick question as the gem description is not entirely clear about this.
For the (base) penance brand, the gem says this about the stored energy:

"

When the branded enemy reaches 20 energy, a large explosion occurs and the brand is removed

I assume that means, that the energy is removed at this stage and (if the enemy does not die) a new brand would start adding energy from 1 again.

That is also what the wiki assumes:

"

Penance Brands apply a stack of Energy to targets they are attached to on each activation, up to a cap of 20. Upon reaching 20 Energy, an explosion will occur at the monster's location, dealing damage to it and nearby enemies. After the explosion, Energy resets to 0 and all attached brands are removed.

Now for the transfigured PB of Dissipation it seems less clear what happens with the energy when the brand expires as there is no explosion, just an "attached duration".

"

The pulse gains area of effect and damage for each energy on the branded enemy.

That makes me think, that the energy is stored on the enemy (rather than the brand).

Now to my question: When then brand detaches after it expires, what happens to the energy? Does it reset to 0 and a new brand that you cast will start back from 1 energy, or does it "save" the 20 energy?

And what happens when you allocate Runebinder and 2 brands are attached (which will expire at different times)?