Old and In the Way
These days I tend to keep my "spare batteries" in multiple vapes. I have two outboard chargers I've been trying to use less and less.You're probably better off investing in a Nitecore digital charger. A lot less hassle charging batteries so you have spares on standby.
I grew tired of unscrewing and screwing grasshopper back ends - for battery swaps and sometimes to improve the connection.
Occasionally I do get the hopper all set with several extra batts for a road trip or something, but usually I'm rotating between several other vapes and I love them all! (Splinter, Milaana3, Go, Mighty, 2 Grasshoppers - see what I mean? And with all but the M3 I tend to leave batts in and just pop the device on a charger. My charging area is a pretty crowded arrangement.)