-------- Built For Fun EV's -------

76Amp Hour of 24V rechargeable lead-acid battery pack. Made up from 4 12V batteries secured in the chassis. Their mass contributes to tractor's low center of gravity.
DC 24V 150Amp reversing battery motor controller on an Aluminium heatsink. The motor controller is the heart of the electrical drive system and delivers the variable 0 to 24V reversible polarity power supply to the drive DC electric motors.

2 x 36V 1000W electric motors running at 24V to deliver 660W each.

Note: The complete drawing set for the Yard Tractor is available from our Plans Order page here.

Not Shown - Instrument panel with ignition switch, battery meter and reverse switch

electrical and control system

See the detailed drawing for the circuit diagram.

The principal elements of the electrical drive system are the DC battery motor controller, the DC electric motors and the rechargeable lead-acid batteries. In addition the motor speed controller requires low power speed "demand" signals (from the throttle potentiometer). There is also an on/off switch, a reverse switch and optionally a battery condition monitor to let you see the stage of charge of the batteries. The DC battery motor controller is at the heart of the system - it takes the fixed nominal 24V from the battery pack and outputs a variable 0 to 24V to the motors. This delivers the tractor's variable speed. By reversing the polarity to the electric motor the speed controller also provides the reverse drive. The motor controller suggested in the plans can be substituted by other similar current rated DC battery motor controllers - you choose.

The 24V 660W DC electric motors are commonly available and are easily mounted and connected to the drive transmission by roller chain.

Standard sized rechargeable lead acid batteries are used. These are manufactured by a large range of suppliers and can provide several hundred charge cycles during their lifetime. You'll also need a good multi-mode battery charger to keep the batteries in good condition.

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2007 - 2008 BFF Design Ltd, Plans provided without warranty or guarantee.

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Click below for Plans pdf Sheet - NOTE password is: "yard"

OvervieW Drawing