need help

I have a Sun EZ3, to which I added a Electro Cycle E4 motor kit about 6 years ago. The E4 kit came with (I think) 12AH Batteries, and all worked well for a year or two, providing 5 to 7 miles of riding. When the 12 AHs gave out I built a frame and mounted 2 55AH which provider 12 to 15 miles range. Both of these setups were charged with the 1.5 amp charger that came with the E4 kit. This year one of those two failed and were replaced with 2 55AH Werkers. I started using a "Cabala's" 8 amp 2 bank charger, or the same 1.5 amp charger, my range is now 2.5 miles! Took batts back to store where I bought them, they checked batts and both chargers, said all were good. Is motor or controller bad?