I've been riding my electrified BikeE "grocery getter" long enough now to wear a Schwalbe Big Apple on the rear all the way down to the Kevlar cords, I figure about 4,000 miles or so (that's why the funky rear tire is on it right now, I have another Big Apple on the way from Amazon). Other than a couple of loose connections in hall wiring and replacing a few dying cells in the pack I've had no electrical or mechanical problems with the rig.
Geared Bafang rear motor running on 12s8p repurposed salvaged 18650 laptop cells. The motor, throttle and controller came from a electric folding bike I bought off Craigslist and the laptop cells came from a friend who works at an electronic recycling center. About 35 miles range currently @ 18 mph cruise, I can carry a weeks worth of groceries and a 20 lb bag of dog food in the trailer with plenty of room left and barely tell it's behind the bike at all. Since the trailer clamp on hitch doesn't fit the BikeE at all I cut a dropout off an old BMX bike and drilled it to screw on the rear of left dropout of the BikeE and that's where I clamp my trailer on.
The bag behind the seat is a large cordura camera equipment bag I got from a thrift store and it holds the battery pack easily with room to spare for a pump, two spare tubes, a few tools and even some shopping items if I'm not doing a major run.
The only transportation I own since I retired, this is a very comfortable and relaxing bike to ride, I can easily go an hour without any neck, butt or hand pain while on a regular bike I can't ride ten minutes without all three bothering me. Since I ride mostly on two lane roads with a fair amount of fast traffic I have made a real effort to be visible with a flag and a Portland Design Works Emergency Zone flasher on both the bike and the trailer and I have a Princeton Tec EOS headlight I set to flashing mode on the front.