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4QD series controller instructions.
7
Controls
The feel, operation and safety of the vehicle will
depend not only on the controller but very much on
the controls you fit. This section discusses some of
the points.
Throttle.
The first decision is whether to use a joystick or a
straight speed throttle plus reverse switch. Joystick
has to be hand operated but a straight throttle can be a
hand or foot control. Mechanically also a straight
throttle will usually be simpler. From the electrical
point of view either is fine - the 4QD is electrically
safe even against direction changes at full speed.
Acceleration.
Unlike a car you will have no gear change, so full
speed is available almost from cold. The 4QD has a
lot of power available for a cold start so that a sudden
application of the throttle will cause a sudden surge
of power. You can alter this by increasing the
acceleration ramp on the board (at the expense of
reducing the responsiveness). A similar adjustment
controls the deceleration rate
Top Speed Adjust.
The facility is also available for an operator top speed
control. Human nature dictates that this will be left at
maximum so it may not be very useful. However it
can give almost the same effect as a gear change:
slow speed to start up, then switch to fast speed.
Electromechanical brake.
Electrical braking relies on the motor acting as a
generator. Therefore when the vehicle is stopped (or
at very low speeds) no electrical braking is possible
and vehicle is free to roll. An electromechanical
brake brakes the motor when no power is applied to it
so that, when the controller is switched off, the motor
cannot turn. The controller automatically applies
power to the brake (to disengage it) as acceleration is
applied and removes power a fraction of a second
after the motor stops rotating.
Mechanical brake.
The electromechanical brake on the motor will only
come on when the motor is rotating very slowly.
Therefore, on steep hills the regenerative braking
works but the electromechanical braking won’t come
on. This is normally what is required but it means
that stopping when going downhill is not possible,
unless a mechanical braking system is fitted. In
theory an emergency brake could be incorporated by
switching off the power to the motor brake, except
that this will place a heavy strain on the gearbox
which could damage it, so this is not desirable.
A mechanical brake also gives the rider confidence,
so that safety can be assured even if the controller
fails. Better to have a brake and not need it than to
need it and not have it!
More reading
4QD have a publication available which is compiled
to answer all the technical questions we get asked.
Called 'Battery Motors and Controllers' it is available
for a small charge (order code PUB-BMC) and it will
answer questions you didn't even know you needed to
ask.
This information is also available via the Internet
from 4QD's www site.
