CONCEPT DEVELOPMENT, IMPLEMENTATION and TEST of an
ELECTRIC PLATFORM on an ADJUSTABLE GO-KART
André, OLIVEIRA, IST/UTL, Lisboa, PORTUGAL, andreoliveirainbox@gmail.com
Abstract - The present paper addresses the
Some other likely chosen batteries are nickel,
cobalt and manganese type ones, known for its
high discharge capacity.
LiFePO4 batteries are also often chosen due
to their high specific energy and power
characteristics.
Regarding to electric motors, there are a few
options that must be compared. The selection is
discussed in [4].
Adjustable features to the children growth are
rarely available on go-kart rental companies.
Further in this paper are described the options
taken to make the longitudinal position of the
brake and accelerator pedals customizable.
Electric go-karts bring all sorts of advantages
concerning simple and clean maintenance, no
need of toxic gases extraction and low cost
energy consumption.
concept development of a new adjustable aluminum
chassis for go-karts.
The new chassis concept is designed based on
an innovative production solution.
An electric functional platform is chosen,
implemented and assembled on a common go-kart
chassis, using a DC motor and a LiFePO4 Lithium
battery pack.
All the holders needed for the electric
components are designed, built and assembled,
using aluminum 8 mm thick plates. The controller
holder is welded using FSW and a T joint.
To adapt the vehicle to the progressive growth
of children, dynamic longitudinal adjustment
systems are designed, built and assembled, for the
brake and accelerator pedals.
Real conditions tests are performed to ensure
the correct working conditions of the prototype.
The final product aims to promote the
improvement of children driving skills and
behaviors inside the track.
2. CHASSIS CONCEPT DEVELOPMENT
The main target of this project is to develop a
new chassis concept, built from an aluminum
5083-H111 alloy, 5 mm thick plate, in order to end
up with a light, innovative, and totally recyclable
structure.
In order to accomplish high quality and
homogeneous welded joints, the structure was
designed to use friction stir welding technology,
promoting the increase of the final product lifetime
period.
Due to the aluminum alloy characteristics, the
weight
reduction
is
an
almost
certain
achievement, however, the need of keeping the
structural rigidity of the chassis is imperative.
Along the designing process different building
aspects were considered, in order to make the
building process easier and doable, such as:
KEY-WORDS Electric Vehicle, Go-Kart Chassis,
Aluminum Chassis, Friction Stir Welding, LiFePO4
Battery, DC Motor application
1. INTRODUCTION
Go-kart racing is available to everyone,
regardless the age and driving skills. There are
different chassis sizes available, usually built with
Cr-Mo steel. The aluminum alloy appliance is a
new feature tested on this kind of vehicles.
Most common go-karts have internal
combustion engines. The power range for children
up to 15 years old is limited to 7kW, considering
leisure purposes. A few engine conversions,
internal combustion engines to electric motors,
have already been made, like in [1] and [2]. They
were powered by 1,1kW and 3kW electric motors
respectively.
Some rental companies have already electric
go-karts fleets especially for indoor purposes,
using Lithium-polymer batteries. [3] In that case
adult go-karts have a maximum 20 minutes
autonomy.
- Design to build attitude. As the aluminum plate
would be cut, and some resulting components
needed bending operations, whenever possible,
the perpendicularity between the laminar and
bending directions were ensured.
- The peripheral components needed to be placed
in strategic places within the chassis, to ensure
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the best weight distribution possible, promoting
one better dynamic behavior of the go-kart on
track.
- Anthropometric data was considered to design
the pedals position adjustments correctly, and
proper to the age range considered, from 6 to 14
years old users. [5] See Figure 1.
Figure 3 – Example of bended components
The chassis frame is made from two half parts
junction, front and rear halves. On Figure 4 are
shown some welded joints which would put
together the two halves that are part of base
chassis structure.
Figure 1 - Dummies at the ages of 6, 10 and 14.
Dimensions in mm.
Figure 4 – Examples of Friction Stir Welded Chassis
The designing process was very iterative, and
as a result, many building options were
considered, designed and their permanency for
succeeding iterations analyzed.
In this paper will be presented the last model,
and described the main features of the solution
reached,
showing
when
needed
some
intermediate information.
Along the iterative process, a new idea came
along, and, to reduce the material waste, an
aluminum AA5083-H111, 5mm thick plate used
for designing was chosen. Some components like
pedals, seat and steering column fixtures were
converted into bended parts and an arrangement
of those was made within the plate area. One of
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the solutions ended up fitting a 1,5m area plate,
like the example shown on the Figure 2.
Joints
The next step would consider the
installation of the remaining structure parts, and
setting-up the chassis to collect all the peripheral
parts of the go-kart. As the kart is being designed
to be an electrical vehicle, all the components
belonging to that installation have been modeled
with the exact same dimensions of those
acquired. The Figure 5 shows the last stage of the
designing.
Figure 2 - Aluminum plate – Component arrangement
After cutting the intended components from
the plate, some would need bending operations
before proceed to the welding stages. The next
figure intends to show some of the components
cut, after bending, and before being friction stir
welded or attached to other kart components.
Figure 5 – Aluminum go-kart chassis concept model
2
The battery pack and the electric motor are
almost similar in their weight, so they were put on
symmetric sides of the chassis to increase the
weight distribution, and dynamic balance.
The controller and the main and reverse
contactors were put behind the pilot seat, to avoid
damages coming from unpredictable external
objects. The final product will include protection
boxes for these components.
Different dynamic adjustments to the children
growth were modeled and its positions checked
with the dummies models. The next picture shows
some of the tests done, experiencing which
adjustments were truly needed and helpful:
Figure 7 – DC motor kit
The kit included the DC motor and its
controller, main and reverse contactors, two
potentiometer types, one control box for
preliminary tests, and current and voltage analog
dials.
I. Permanent Magnet DC Motor
This DC motor is a permanent magnet
brushed type motor, capable of 4,8kW continuous
power, with 13 Nm rated torque. The folllowing
table shows briefly some of the most relevant
features about the electric motor, and compares
them to an equivalent internal combustion engine
used in leisure karting applications:
Figure 6 – Dynamic adjustments to children growth overview
Honda Motor
DC Motor – ref. Mars 0708
To proceed with the building of the aluminum
chassis, a new approach had to be made due to
the complexity of the designing FSW needed
fixtures process.
Acquiring a used go-kart chassis allowed the
electrical and electronic tests to be done on track,
and also, it turned out an excellent starting point
to initiate the structural revolution.
200cc – Gx200
Voltage
48
V
Power
4,8
kW
Continuous Current
100
A
Max. Current
300
A
-----
Efficiency
85
%
N.a.
----4,8
kW
-----
Speed
3200
RPM
3600
RPM
Rated Torque
13,1
Nm
8~12,4
Nm
Max. Torque
38
Nm
13,2
Nm
Weight
13
kg
16,1
kg
Specific power
0,37
kW/kg
0,26
kW/kg
3. ELECTRIC VEHICLE TECHNOLOGY
As this go-kart is being designed for children,
and for learning purposes its performance
characteristics should be limited to a specific
level. The Portuguese Karting Federation has
established power levels depending on the age of
the users, and so, for leisure karting activities, for
children until 14 years old, the maximum power
available must be below 7kW, with 90km/h of
maximum vehicle speed. [6]
A DC motor drive is chosen because it can be
purchased at low price, and it is easier to be
electronically controlled. [7]
A complete motor kit was acquired, the one
seen in the Figure 7:
Table 1 - Comparison table between electric motor and
internal combustion engine [8], [9]
II. Battery LiFePO4
In order to reduce the battery pack weight,
lithium type batteries were acquired. [10] The
bought pack was built with 30 LiFePO4 individual
cells, with 3.2V and 10Ah each, which were then
connected between them, reaching the final
values of 48V and 20Ah of capacity. For safety
reasons, a battery management system was also
included, to increase the fault-tolerance of the
battery usage. The final specifications are shown
on Table 2.
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Parameters
Cell
Final Pack
Capacity
10Ah
20Ah
Voltage
3,2V
48V
Charging Voltage
3,65V
58.4±0.05V
Cut-off Discharge Voltage
2,0V
32V
Max. Discharge Current
150A
100A
Max. Charging Current
60A
20A
Weight
307g
this case, around 10A. This stage is the most
important since it pushes de state of charge from
5% to 90% approximately. To finish the charging
process, a constant voltage value is used, where
a small current will fill the battery up to its
maximum capacity. Acting this way, every cell is
ensured to be with the same state of charge
percentage.
The discharge in this specific case is done at
constant 10A, fact that lasts around 60 minutes as
it would be expected due to battery capacity.
The lifetime of the battery pack is around
2000 cycles, announced by the manufacturer.
12kg
Energy Density
105Wh/kg
Power Density
850W/kg
Table 2 – Individual cell and final battery pack specifications
The assembly of the battery pack, with
battery management system included can be
seen on the Figure 8. The blue tubes are the
individual lithium battery cells.
III. Controller
The controller used was a Kelly KDZ PM Motor
controller [7] with ref.KDZ48401.
This programmable controller provides efficient
and smooth controls for electric vehicles
applications. This uses high power MOSFET and
fast PWM to achieve high efficiencies and also
allows users to set parameters, conduct tests, and
obtain diagnostic information quickly and easily. It
operates at a frequency of 16.6 kHz, and is
capable of delivering a motor current of 160A
continuous.
Figure 8 – Battery pack assembly
4. IMPLEMENTATION AND TEST OF THE
This type of battery has an specific charge
and discharge cycle. To better understand that
process, the Figure 9 shows the voltage and
current timeline of one entire cycle.
ELECTRICAL COMPONENTS
A preliminary test stand was built to verify all
the electrical components working conditions. The
controller was programmed with a safe parameter
configuration, limiting the motor current to 80A
maximum; setting the cut-off voltage to a higher
value than the one set on the battery
management system; and the braking energy
regeneration was turned-off.
While choosing the wiring specifications, some
regulations were followed as high currents can
promote wiring heating due to Joule effect. A table
of regulated electric conductors was consulted,
leading to a recommended conductor section area
2
of 25mm , for a copper pvc coated cable, exposed
to ambient air. The maximum current possible
with such conductor is 126A. The cables acquired
followed those specifications.
In order to collect LED information about
running or faulty operation, a small display was
built and installed on the static steering wheel.
Also, a small aluminum base was built to allocate
the voltage and current dials. The Figure 10
shows final assembly of the preliminary
workbench.
Figure 9 – Performed charge and discharge cycle of an
individual cell
The charge-discharge cycle shown is a
CC/CV type, constant current and constant
voltage. There are four periods within one cycle.
The first one refers to a discharged state, where a
very small current to recover the voltage to its
rated value. Then, a large current value is used, in
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Estimated Weight [Kg]
Go-Kart chassis
80
DC motor
13
Battery Pack
12
Controller
3
Total
108
Table 3 - Estimated Weight
5. AJUSTABLE FEATURES DEVELOPMENT
Figure 10 – Final assembly of the preliminary test stand
Regarding the adjustable features to the
children growth, longitudinal adjustment systems
were designed, built and implemented for both
accelerator and brake pedals.
A quick adjustment system was built from a
thick aluminum plate and two fast clamping cams
usually used on bycicles. Figure 13 shows the
process from development system:
All the components were in good working
conditions, so the work proceeded to the next
stage. A common go-kart chassis was acquired
and all the electric components were then
implemented on it.
The Figure 11 shows the initial kart frame
shape. Some usual components are already
missing, like the combustion engine, the gas tank
and the muffler.
Figure 13 - Accelerator adjustment system
For the brake pedal adjustment system, once
it is a critical component during the regular use of
a go-kart, a different system was developed.
Although it requires more time to operate, it
reduces the chances of failure when compared
with other quick adjustment options. Figure 14
illustrates the stages of development of this
system of adjustment.
Figure 11 – Initial kart frame shape
All the electric installation was implemented
and tested before going to the track. The
controller set-up was kept with the same safe
configuration as the laboratory workbench tests,
to minimize the chances of failure events to occur.
The Figure 12 shows the final look of the
prototype before performing the first track tests.
Figure 14 – Brake pedal adjustment system
The electric motor holder was built in steel
once the dynamic loads are very demanding
along track running conditions. Figure 15 show
the development of this component.
The final position of the battery pack also
required the construction of a specific holder. After
studying a few options, a final solution was
worked out, meeting the fixture requirements of
Figure 12 – Final look of the prototype before the first
track tests
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this particular battery pack. The Figure 16 shows
the battery pack holder development.
Figure 18 - Fixture structure for welding purposes
Figure 15 - Electric Motor Holder
The Figure 19 shows two simplified views of the T
joint and used pin:
Figure 16 - Battery pack holder
While designing this holder, weight distribution
and protection against unpredictable external
objects were considered.
Finally, the controller also needed a holder.
The available space in the kart chassis to fix this
component was somewhat limited, and because
of this the development was more complex. The
chosen place for setting this component was the
backside of the driver’s seat. Therefore the
electronic components are protected from external
objects. Figure 17 shows the development done
around this holder.
Figure 19 - T joint illustration
The following table summarizes the parameters of
the welding process:
Material: AA5083-H111, 8mm thick
Welding Position
8,2 mm
Tool Force
1300 Kg
RPM
800 r.p.m.
Dwell Time
4,0 s
Plunge Speed
0,1 mm/s
Welding Speed
10cm/min
Table 4 - Welding Parameters
The final look of this holder, after welded and
bended, is shown by Figure 20.
Figure 17 - Controller holder
The designed shape of this holder would
require a welding operation, using a T joint. The
FSW process was chosen for this application. A
strong structure for positioning and keeping the
welding parts stuck, was needed to meet the
requirements of running such a process. This
structure has been developed and the weld has
been accomplished, as shown in Figure 18.
In order to reduce the need for penetration,
and to avoid the use of a slender tool, a small
3mm cavity was created on the horizontal plate.
The used pin was 8 mm height, with helical
grooves.
Figure 20 - Final controller holder look
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Later on, the welded joint was checked through
NDT techniques. After those tests no defects were
found along the length of the weld.
Finally, regarding the steering column, the
adjustment on its length was not included due to
the high demanding loads existing while running.
However, the angular adjustment is available
but only in two different positions. Specific
positions are possible at 41 ° in the lower position
or at 46.5 ° in the upper position. This adjustment
is made with a threaded connection and requires
auxiliary tools to perform the change. The
mentioned angles are measured between the
column axis and the horizontal plane of the
chassis. The differences between these two
positions can be seen in Figure 21.
REFERENCES
[1]
C. Cardoso, J. Ferreira, V. Alves e R. E. Araújo, “The
design and implementation of an electric go-kart for
educational in motor control,” em
International
Symposium on Power Electronics, Electrical Drives,
Automation and Motion, Taormina, 2006.
[2]
B. Heffernan, “A go-cart as an electric vehicle for
undergraduate
Universities
teaching
Power
and
assessment,”
Engineering
em
Conference
(AUPEC), 2010 20th , Australasian, 2010.
[3]
“OTL
Italia
Karts,”
[Online].
http://www.kart1.us/electric.html.
Available:
[Acedido
em
Setembro 2012].
[4]
K. W. E. C. a. N. C. C. X. D. Xue, “Selection of
Electric Motor Drives for Electric Vehicles,” em
Australasian
Universities
Power
Engineering
Conference, 2008.
Figure 21 - Different angular positions of the steering column
[5]
6. CONCLUSIONS
A. R. Tilley e H. D. Associates, The Measure of Man
and Woman: Human Factors in Design, Estados
Unidos da América: John Wiley & Sons, 2002.
The following conclusions can be drawn:
[6]

A prototype of an electric functional go-kart
named eKidART, with adjustable pedals for
different children’s sizes, was produced and is
ready for testing;
F. P. d. A. e. Karting, “FPAK - Recomendações para
Karting
de
Lazer,”
2012.
[Online].
Available:
http://www.fpak.pt/REG2012/regulamentos_2012.htm.
[Acedido
em
Setembro 2012].

The support for the electric controlling system
was designed, and constructed in AA5083-H111,
including the FSW process;
[7]
“Kelly Controls, LLC - Lead to clean the World,”
[Online].

The T-joint produced with FSW was
inspected using ultrasonic non-destructive
technique. No defects were found;
Available:
www.kellycontroller.com
.
[Acedido em Março 2011].
[8]
L. Streit, “Concept of electric kart with LiFeYPO4
batteries,” em 2011 International Conference on

The final chassis was set on a conventional
tubular steel structure assembling several
components in aluminium alloy that were
designed and produced with conventional
technologies;
Applied
Electronics,
Pilsen,
República
Checa,
Setembro de 2011.
[9]
“Motores Honda - Manual do Proprietário - GX200,”
[Online].

The electrical motorization solution adopted
was designed and assembled in the eKidART
based in components available in the market;
Available:
http://engines.honda.com/pdf/manuals/37Z4F603.pdf.
[Acedido em Agosto 2012].
[10] “Headway,”

A new concept for the chassis based on one
1000x1000x6 aluminium plate (dimensions in mm)
was designed considering the application of FSW.
[Online].
Available:
http://www.chinaheadway.com/. [Acedido em Março
2011].
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