Battery Box for Ebike
Do you know if your kit will fit inside this box?
I'm not sure, I haven't used that specific case. But you can see the size of the caps on a cell and determine for yourself.
For me the main benefit is two-fold: 1) being able to put different batteries on (including different sizes and voltages), as well as being able to easily build multiple custom batteries.
I live in a city with significant ebike theft, especially batteries. If I know I'm going to a bad part of town, I'll toss on an old, beat up battery. My bag locks, but even so, I try not to leave my bike unattended for too long. Anyone could of course cut the bag.
If I'm going on a longer trip, I'll use a bigger battery. If I want to go faster that day, I can use a higher voltage battery.
For me, it's just more flexible. But the advantages for me are disadvantages for others. To each, his own.
I prefer a triangle bag that goes in the front triangle of the frame. A bag on the rear rack has many of the same advantages, but I don't like the weight being up so high, and it's also weird having it that far back. It can induce some weird handling issues sometimes. At least, that's the way it feels for me. Having the battery weight between your knees just feels much more naturally balanced to me.