If you want extended range and fast charging, you can also get a GrinTech Satiator charger . You won't even need to carry the spare. Can charge it @6amps, the battery is between 11.6-12.6ah , very okay to charge @6ah, even 6.5.
@Ebiker01 , You need to be careful about dispensing this kind of advice here.
I just looked at this charger on Amazon, and in the reviews/question and answers section, Grin themselves says this won't work with Bosch systems without 'hacking' the system.
Amazon.com: Grin Tech Cycle Satiator - Programmable Electric Bike Battery Charger - 24, 36, 48, 52 V : Automotive
Buy Grin Tech Cycle Satiator - Programmable Electric Bike Battery Charger - 24, 36, 48, 52 V: Automotive - Amazon.com ✓ FREE DELIVERY possible on eligible purchases
Here is a screenshot.
At best, someone could be spending north of $300 on a charger that won't work. At worst, they could cause damage to a very expensive battery/motor system and invalidate the warranty at the same time.
Even if it did 'work' out of the box, I'm not going to take a chance fast charging what amounts to a $1000 battery and take a chance on compromising it or reducing it's service life.
Also, this unit requires AC power, and where I normally ride, that is not an option (i.e. out in the boonies)