Page 6
4QD series controller instructions.
The controller will normally be supplied with these
adjustments set to suit a typical application - so you
may not have to alter anything.
There are five possible adjustments, two of which
(marked ¶) you should
not
touch unless you are quite
technical.
Refer to the 'Features' diagram to locate the
adjustments.
Gain
This also acts as a pre-set top speed adjust.
The purpose of the gain control is to match the
controller to the speed pot arrangement, since a twist
grip may use only 90° of the available electrical
travel whilst a plunger pot will use all of it.
The 'Gain' control is marked on the features diagram
and has a G against it on the circuit board.
To set the gain, first chock up the drive wheels so
they are clear of the ground and free to rotate.
§ Switch the controller on and select forward
direction.
§ Have an assistant hold the throttle at full speed.
§ Adjust the Gain preset pot.
¤ Turn it down (anticlockwise) until the wheel
speed starts to decrease.
¤ Now slowly turn it up (clockwise) until the
wheel speed is just at maximum and
won’t increase any more.
It is easiest to do this if the Accelerate adjustment is
fully anticlockwise (minimum ramp).
If this gain adjustment is too low
the vehicle will
loose top speed -it is then being used as a 'top speed'
adjustment but do not cut the top speed too much.
If you need to do this it means your gear ratio is too
high and this will cause excessive motor current.
If this gain adjustment is too high
the controller will
reach full speed before the throttle pot reaches
maximum deflection so there will be a 'flat' spot at
full throttle. Also, reverse speed will now be more
than half maximum speed.
Ramps
These control how sharply the machine accelerates or
decelerates when the throttle is actuated sharply.
Acceleration
. The preset marked A on the diagram
adjusts the acceleration rate. Too long an acceleration
time (clockwise) and the vehicle will be slow to pick
up speed. Too fast a rate and the vehicle may do a
wheel spin or, if badly balanced, will do a wheelie or
dislodge the driver. Factory setting is at about 10
o’clock
Deceleration
rate is adjusted by the preset marked D
on the diagram. Too slow a deceleration and the
braking will be ineffective in an emergency but too
sharp a deceleration may throw the rider off the front
of the vehicle. Normally this is best set slightly below
acceleration, so the standard factory setting is at
about 9 o’clock.
It is usually easiest to adjust these empirically.
Factory settings are about right for 6-8 mph vehicles
with fairly fast response. Trim them by trial and error
to adjust the vehicle’s handling as you require. Fast
vehicles need longer ramps than do slow vehicles.
The ramp times are variable over a very wide range
to allow for fast vehicles. By arrangement 4QD can
alter the adjustment range for various uses.
¶ Current
this should not need adjusting: this is set at maximum
when the controller leaves the factory and there is
little point in altering it - unless you think the motors
will be damaged by the available stall current.
¶ Reverse Acceptance Threshold.
Adjusting this requires a little technical
understanding. It is marked RAT on the diagram
(page 4).
Factory default:
the threshold is set to maximum
which suits most machines. The adjustment controls
the threshold at which the controller will reverse.
Normally the controller should reverse the motor
before it is completely stopped.
We suggest you do not adjust this.
It may need slight
reduction for higher battery voltages and/or for low
rolling friction vehicles.
8
Adjustments
