Alright so I finally rode it until the battery cut off. So it looks like the absolute range is 13 miles (+/- 1 mile). So that means I was only getting about 5-6 "useful" miles out of the SLAs, I could go a few more miles after that but I would have significantly less speed and torque due to the SLA's voltage sag.

The new batteries went all the way to 13 miles and the last mile or two was when it had "slight" drop in torque. Which means I would have only noticed it if I had tried to go on sixth gear (which is the gear I need to use to get to 25MPH). So even after near empty battery I could still get around 22MPH out of it. The SLAs would have me stuck on 17-18 MPH after half the battery was used up.

As for the battery meter. It's completely inaccurate. It never drops past the second bar and every time I turn power off and come back to it later, it would rebound back to full and would drop one bar after a few more miles of riding. It wouldn't drop one bar until I was roughly 75% through the battery capacity. So at this point I will probably just get rid of it once I get a new battery case. I'll stop it at 10 miles and put it on recharge anytime I hit 10 miles. And this is all on 100% electric by the way since my bike does not yet have the pedals connected to the chain. Thus I did no pedaling on it.