The overstock is so that that you never have the experience of running out of power and having to wait for batteries to charge.
I keep the battery charger in the breezeway into the old cottage, just beneath the pegboard tools storage. I keep fully charged batteries on the pegboard so they can just be grabbed as needed. Batteries in need of a charge go directly into the charger sitting on the self below the pegboard. When I walk by, if I notice that there are completed batteries in the charger, I just transfer them up on the pegboard holders.
Here's my design of the pegboard battery station:
Those designs translate into reality as these:
You can download this design at my Pegboard Battery Storage entry on thingiverse.com