c65, aaaaaaand there's our answer to super-sustainable kids, or almost. That quad hydra is already making 3.2kg/s of o2 and 224g/s of h2. The righthand chamber still needs priming, but that won't take long, then we'll have 448 gs.
Now, this is self-powering, that's why there are four generators in there. If those were up all the time, it'd consume all the h2. But they never really will be, cuz the smart batteries.
We'll easily run 3-5 more generators off the excess.