NSEU: Mate I'm not stupid
Of course you'd need to have enough fuel to descend to 10,000'. Most of the time mid-Pacific you'll have 70 to 80 tonnes of the stuff, enough to fly to the nearest suitable airfield at 10,000' I chose 10,000' so you could depressurize the ship BEFORE you lost ALL power to the valves. And yes this would only work in daytime VMC.
So, answer my original question: Couldn't you just turn off the battery to conserve power AFTER you've 1/ descended 2/ depressurized 3/Advised ATC and 4/ worked out Navigation .
This must be better than pulling god knows how many cb's powering god knows what.