Hey so a few mnoths ago I bought 8 SLA batteries 12v 7ah each, and at first i had got about 3 to 5 miles per charge out of them and now I have them wired for 72v hoping my bike achieves 40 mph but the batteries for some reason are so weak that they barely will get me a mile on a charge and it wont go any faster than 32 mph. I am wondering why is this, the batteries were just bought like when fall began and they are already failing on me. Anyone got any recommendations for better batteries not too expensive i am looking at about maybe $150 budget to spend on ebike batteries that will; atleast give 5 or more miles per charge. Or is there a way I can fgix the batteries I currently have now?