choppa 1choppa 2choppa 3choppa 4choppa
OwnerDean Hosken
Owner's Other EVsScoot Mk2
Scoot MK1
LocationNewcastle, New South Wales Australia map
Email email image
Vehicle2008 Karat-E-Choppa
Scratch built mini chopper
MotorAdvanced DC K99 (or apparently K91) Series Wound DC
K91 with a funny shaft which I cut down.
Drivetrainchain direct drive with jackshaft.
3.8:1 ratio
ControllerAlltrax 4834
Batteries4 DiaMec 26Ah, 12.00 Volt, Lead-Acid, AGM
Got these cheap through work. I will use these for testing, but they will probably not give much range.
System Voltage48 Volts
cheap 2.5 amp charger.
Instrumentationbike speedo
Top Speed47 MPH (75 KPH)
best so far is 75 km/h.
AccelerationGetting better. I have controller set at 45%.
Range9 Miles (14 Kilometers)
Better than expected considering the cheap batteries.
Watt Hours/Mile75 Wh/Mile
This is a rough estimate. Due to the peukert thingy, I only get about 15Ah out of these batteries. I should get one of those power meter things and measure the charge cycle.
EV Miles
Current:80 Miles (128 Kilometers)
    As of 6/12/2009
Seating Capacity1 adult
Curb Weight200 Pounds (90 Kilograms)
Quite heavy. Not sure heavier batteries would be a good idea with the bicycle forks.
Tiresrear: 90/90 12R road tyre for scooter
front: 20 x 2.1 bmx road tyre
this is still under construction. I am pretty keen to get it going! should be a ball tearer.

17/07/08 Did some testing. Have controller limited to 30% since I have only 8 gauge cable at the moment. Went better than expected considering the current limit. Tried it at 45% and got better hillclimbing ability but I think that was pushing the limit of the batteries and maybe the cable too. It did 14km before it became really slow, but low battery cut-out hasn't happened yet, it is set at 40V. 65km/h feels pretty fast on it. Motor is just cruising though, doesn't even get warm at all.
Love it!

27/07/08 Upgraded cables to #4 awg, and geared it up a bit. Did 75km/h easy. Acceleration improved noticably, so the #8 awg cables were holding it back even at 45%. Now I have bigger cables I'll have to wind it up to 100%!

Painted it

Not much improvement at 100%. I think batteries are struggling to provide more than 180A on take off.

Crashed it! Showing off at work. Not serious, bent pedal, scratched endbell.

10/06/09 All fixed now and loving it once again!

code by jerry