well on positive note.
I own MERIDA pedal first bicycle and tried several SLA brands.
B&B is the best hand down, do your research and common opinion is they last longer and voltage don't sag as much as oter brands.
I tried LONG and HAZE brands.
Haze has too much sag.Long is not bad but not as good as B&B.
Definitely don't discharge more than say 60-70% , never discharge to LV cut off and it will last, never leave it after ride without charging, eveen 1 hour after ride.
MC