I 3D printed a box to hold about 50 AA batteries. All the battery negative poles touch the bottom of the PLA box. i wonder if it would be a bad idea to place a metal plate at the bottom of the box so that the batteries are all grounded tho the plate. The box offers access to the positive pole of the batteries so I could quickly check the voltage of batteries and discard those that have fallen below a certain voltage (say 1v). Seems like this would not be an issue but after i got myself into trouble about “ground loops” a while back, might be better to get guidance.