• Top-Speed: 35 km/h forwards and backwards
• Weight: 240 kg
• Turning radius: 0,5 m
• Brake: Rear only, wooden block
• Suspension: Rear swing arm only Features
• Switch for selecting driving direction
• Switchable differential-lock
• Front light
• Trailer hitch

Front view of the finished vehicle

Electrical

Motor

• Type: Serial wound DC motor
• Previous application: Forklift
• Power: 2,9 kW
• Voltage: 24 V
• Current:
  • Rated: 156 A
  • Measured: 25 - 500 A
• Rotational speed: 1780 rpm

Control

• Custom PCB with ATMEGA 8 microcontroller
• Control method: 124 Hz PWM
• 600 A 1000 V IGBT (FUJI 1MBI600PX-140-01)
• Audi gas pedal
• Custom knife switch for direction selection
  
  

Early setup with temporary wiring Direction selector, IGBT and Diode

Mechanical

Drivetrain

• Custom adapter from motor (helical cut spur gear) to sprocket for chain
• Chain: 06B-1(3/8’ x 7/32’)
• Sprockets:
  • motor: Z13
  • axle: Z40

Tires

• from car trailer
• 4.80/4.00-8
• Tubeless
• diameter 400 mm

Drivetrain maintenance

Battery

• Voltage: 24 V (2x 12 V in series)
• Capacity: 2,4 kWh (2x 12 V 100 Ah)
• Type: Deep cycle AGM

Experience with battery types: Over the years different kinds of batteries were tested:

1. VRLA Starter battery
   • Positive: Very high discharge current
     -> Noticably higher motor torque
   • Negative: Fast loss of capacity when discharged too much and often
     (bad deep cycle capability)
2. Lead GEL battery
   • Positive: Suitable for very deep cycle applications (high actual usable capacity, with comparably less capacity loss)
   • Negative: Low discharge current
     -> Significantly reduced torque in combination with this very current demanding motor (was almost unusable)
3. AGM deep cycle battery
   • Slightly less discharge current than the Starter battery, but higher cycle stability
   • Best option so far
4. Lithium-Ion battery?
   As Experienced in the E-Bike and Armchair projects, Li-Ion would be the best type in terms of weight to capacity ratio and cycle stability.
   But building a lithium-ion battery in the appropriate size for this project would simply be too expensive.

Different battery types used: VRLA, GEL, AGM deep cycle


Battery change

layout front

finished board