Documents discussed during congressional hearings June 17, 2010, suggested that a battery in the device's control pod was flat and that the rig's owner, Transocean, may have "modified" Cameron's equipment for the Macondo site (including incorrectly routing hydraulic pressure to a stack test valve instead of a pipe ram BOP) which increased the risk of BOP failure, in spite of warnings from their contractor to that effect.
The current Chevron well in the Basin is almost twice as deep as the Deepwater Horizon well in the Gulf, possibly posing increased risk for blowout preventer failure.