I believe from 2014 on they used the bigger battery. I will say in level mode 1, I get tons of miles even with the smaller battery (10.5 amp hours).
I have been over 40 miles and believe I can get as much as 50 on a single charge. My battery works perfectly but it would be very cool to double my range with a spare.
The not so cool part is it would cost me $900 when all is said and done. If for some reason my battery dies before the warranty is up I will be very excited to get the bigger one.
Probably the quickest way is to call Eflow support with the serial number. If you can, weigh the battery and ask them about the weight difference between the 10.5 and 14.5.
I would think there has to be at least a 1/2 pound difference but don't know for sure.