PROBLEM SOLVED:
Short answer is it was the connection BETWEEN the batteries that was the culprit. Tightened those up and viola, it worked! Top speed now is 22mph! Loving it.
THE STORY:
Last night on my test run, I hit 17mph. It still kept losing full acceleration every few seconds. Finally, the whole thing just stopped moving. I had still thought it was a bad connection from the battery cable to the controller, so I replaced that this evening after work. I even stopped by Harbor Freight Tools to pick up a proper crimping tool. When everything looked pretty, I turned it on and nothing.
"Ugh," I thought.
I took the volt meter to the wires connecting to the controller and this time it was way under. Instead of 37v, it as reading 6.8v and wasn't even consistent. Numbers kept jumping around. I tried charging the battery itself thinking maybe I messed up the battery by going full throttle for two long the night before. The charger light wouldn't even turn on solid. It kept blinking red/green irregularly. Since the throttle light wouldn't even turn on, I knew it had something to do with the battery.
Opened up the case, and got 0.6v. That's a bit odd for a 36v battery pack. While I had the battery case open, I replaced the charge port that I burnt the other day. Looked over and saw that one of the connections between the batteries was loose. When trying to fix that, I noticed another connection had completely come off! Ooops. The whole time it was a bad connection
between batteries and
not the connection between the battery to the controller! Haha. It was that simple!
Before putting battery case lid back on, I turned on the cooler and voila! The lights came on! Put everything back together. Turned it on one more time and still saw lights. Took a test run down the block and hit 20mph! I was trying to get catch a screenshot of it. Bit of a challenge being that I was trying to hold my phone while steering. Not a good idea by the way. I did manage to get a screen shot of my Speed View app at 22mph!
From there, I was smiles cheek to cheek and waved at all the neighbors staring at me as I rode along. Fun times.