If you cannot find an aux18l, a etx18l will fit but you have to buy sae terminals. : r/BMWi3
ETX18L | Power Sport Batteries | Impact Battery | Impact Battery
USA-Made Big Crank™ ETX18L Battery - Free Shipping | Battery Mart
Deka Gel Battery Harley Replacement Softail Dyna Chopper ETX16L Custom – American Classic Motors
MIGHTY MAX BATTERY Y50-N18L-A3 GEL Sports Battery Replaces 18L-BS ETX18L CY50-N18L-A3 MAX3511561 - The Home Depot
12 Volt Power Sports Absorbed Glass Mat Deka Batteries powersport 12 volt AGM DC power electrical storage recyclable maintenance free valve regulated spill proof | Auto Value