yep if you are charging your "passthru" capable device with lets say a 1 amp charger which is common. And your atty uses 3 amps of current 2 amps of current must come from the battery, therefore while you vape the battery is in fact discharging instead of charging. And most attys use far more than 3 amps of current.
I spoke with P Busardo about this via email about the reviewers not making this clear in their reviews. He replied back that they do say this but I had only seen him do it once in his reviews. Ohh Well.