I've got one of the all-battery packs coming which has 8 cells instead of 4, so I'm planning on just moving to a bigger bag anyway and losing the included bag.

I will probably try to find a waterproof handlebar bag, or to make the bag I use waterproof, perhaps just with a ziplock.

I just noticed this morning that the insulation on my MS pack's connector has split and the wires inside have become visible. This is the case even though I've been very careful to only grasp the connectors when separating them. Apparently just the act of twisting the two connectors (which is absolutely necessary to separate them by hand) is enough to damage the insulation.