A 'basic' 72Volt Xebra SD (Sedan) is good for about 35MPH on the flat. Maybe a little more but not much and it drops to 30 on a mild grade. The GPEV (Sean) 84Volt version is good for a solid 40MPH on the flat and will hold 35 on the same grade. We wanted more of course. There are 45MPH roads on the way to work.
First thing to check was the speedometer. They're notoriously innacurate on Xebra's. We went out and checked it against a car with a known speedometer. Surprize! It's accurate within one MPH!
Second, there's some drag and tracking problems. There will be another post on that.
Third was to change the gearing (in effect) by putting on slightly 'taller' tires.
See the last part of the post below for how that works.
We took off the 145/70R12 tires and mounted 155/80R12. The new ones have about 8% greater circumference.
Results: One mile to get up to speed and then one mile with the pedal all the way down. Same course and full charge in both cases.
Before: 41-Maybe-42MPH
After: 43-Maybe-44MPH
Pretty much what you'd expect. We also ran it up our 'test hill' and couldn't see any speed difference (controller is in current limit mode). I'd say this counts as a success.
We have noticed that after it cools down from being charged the pack shows about 92-93 volts. The controller allows a maximum of 100Volts. Looks to me like there's room for another 6V battery. 90V Xebra anyone?
