8/7/2019 (SAE_BAJA_2010)

1/36

1

Electrical Systems &

Accessories

A Minor Project Report For

SAE BAJA 2010

Guided By:

Prof. Ibrahim Hussain Shah

Prepared By:

Madhav Gupta

Aniket Basu

MediCaps Inst of Tech & Mgmt, Indore

8/7/2019 (SAE_BAJA_2010)

2/36

2

Outline

Starting Circuit

Recharging Circuit

Accessories

8/7/2019 (SAE_BAJA_2010)

3/36

3

Engine Specifications LGA-340

Bore x Stroke : 84 mm x 64 mm, Singlecylinder, Air Cooled

Swept Volume : 338 cc

Compression ratio : 8:1

Rated Power : 8.1 kW @ 4400 rpm

Max Torque : 19 Nm @ 3000 rpm

Valve Timing System : Belt Driven Single OverheadCamshaft

Lubrication : Forced Lubrication

8/7/2019 (SAE_BAJA_2010)

4/36

4

Specifications LGA- 340 (Contd..)

Luboil Capacity : 1.7 litres

Starting System : Electric Start

Electric System : 12V, 18 amps alternator

Recommended Battery : 12 V, 44 Ah

Weight of Engine :30.5 kg

8/7/2019 (SAE_BAJA_2010)

5/36

5

Engine Layout

8/7/2019 (SAE_BAJA_2010)

6/36

6

Overall Dimensions

8/7/2019 (SAE_BAJA_2010)

7/36

7

Components of Electrical Systems

8/7/2019 (SAE_BAJA_2010)

8/36

8

Batteries

Primary electrical storage device onoff-road equipment.

Is discharged upon starting, andrecharged during operation.

Lead-acid batteries are the primarysource of electrical power in off-road equipment.

8/7/2019 (SAE_BAJA_2010)

9/36

9

Lead-Acid Battery Diagram

8/7/2019 (SAE_BAJA_2010)

10/36

10

Circuit Model for 12 V Battery

8/7/2019 (SAE_BAJA_2010)

11/36

11

Battery Construction

ABS plastic case

Lead calcium alloy plates reduced

gassing and water loss Earlier batteries used lead antimony

alloys requiring more maintenance

Glass fiber matt used to separateplates and add strength

8/7/2019 (SAE_BAJA_2010)

12/36

12

Sizing Batteries

Starting loads provide the greatestdemand to battery charge.

Charging systems must be able torecharge battery in time for nextstarting cycle.

Energy efficiency of a battery is the

ratio of discharge energy tocharging energy for mostbatteries this is 75%.

8/7/2019 (SAE_BAJA_2010)

13/36

13

Cost Factor (Battery)

Recommended Battery is a 12V &44Ah.

May cost nearly about Rs.1500/-

8/7/2019 (SAE_BAJA_2010)

14/36

14

Charging Systems

Engine driven alternator withintegral voltage regulator

Stationary coils (stator) withrotating coil (rotor).

Claw pole is the most commondesign.

8/7/2019 (SAE_BAJA_2010)

15/36

15

Claw Pole Alternator

8/7/2019 (SAE_BAJA_2010)

16/36

16

Three Phase Rectification

8/7/2019 (SAE_BAJA_2010)

17/36

17

Alternator Sizing

Alternator performance curves canbe utilized for sizing.

Alternator must be capable ofmeeting the long-term loaddemands, plus recharging thebattery.

Long-term load demands include:fuel pump, head lamps, worklamps, instrument panels, controlsystems, and battery charging.

8/7/2019 (SAE_BAJA_2010)

18/36

18

Alternator Performance Curve

8/7/2019 (SAE_BAJA_2010)

19/36

19

Alternator Sizing

Alternator should be able to supply130-150% of long-term loads at

idle engine speed.

8/7/2019 (SAE_BAJA_2010)

20/36

20

Cost Factor (Alternator) Alternator may cost around Rs.

2200/-

8/7/2019 (SAE_BAJA_2010)

21/36

21

Starting Systems

Electric motor

Engagement mechanism with spur

gear Spur gear to ring gear ratio of 10:1

to 15:1 is common

Gear reduction if necessary somestarters utilize a planetary reductionto increase torque

8/7/2019 (SAE_BAJA_2010)

22/36

22

Starter Cutaway

8/7/2019 (SAE_BAJA_2010)

23/36

23

Starter Motor

Typical DC motor design with fieldcoils, armature, and brushes

Field windings are either series-wound or shunt-wound.

Series-wound motors have highlocked-rotor/low-speed torques.

Change-over relay is required in24 V starter circuits.

8/7/2019 (SAE_BAJA_2010)

24/36

24

Starter Selection Considerations

Engine must rotate 60-140 rpmwith starting aid.

Maximum voltage drop troughbattery cables should not exceed0.1 V for 12 V systems and 0.17 V

for 24 V systems.

8/7/2019 (SAE_BAJA_2010)

25/36

25

Engine and Starting Torque Curves

8/7/2019 (SAE_BAJA_2010)

26/36

26

Starting Circuits Design

Safety interlocks to prevent inadvertentstarting when shields have been removedor when the transmission is in gear.

Design should discourage or preventelectrical connections at starter motorsolenoid or starter relay to prevent

operators from being run over.

8/7/2019 (SAE_BAJA_2010)

27/36

27

Lighting

Purpose of lighting includes safety,instrument and work functions.

Work lights illuminate surfaces thatmust be seen in the dark to permitvehicle operation.

8/7/2019 (SAE_BAJA_2010)

28/36

28

Lighting

Incandescent and halogen lights arecommon, the latter is beginning todominate the market.

Light efficiency: incandescent 10-18lm/W, halogen 22-26 lm/W.

8/7/2019 (SAE_BAJA_2010)

29/36

29

Lighting Accessories Selection

Headlamp : 12V- 35W/35W

Tail lamp : 12V- 5/10W

Instrumentation : 12V- 3.4W

Horn : 12V-DC

8/7/2019 (SAE_BAJA_2010)

30/36

30

Cost Factor (Accessories)

Tail lamp (with switches) may costRs. 80/- to Rs.120/- per piece

Headlight (with switch) may costRs. 80/- to Rs.120/-per piece

8/7/2019 (SAE_BAJA_2010)

31/36

31

Power Distribution

Cable/wire sizing factors: mechanicalstrength, temperature rise, voltage

drop, and connectors. Minimum cable/wire size of 1 mm2 for

area susceptible to damage arerecommended.

Consider requirements for abrasionresistance, bend strength and fluidresistance for battery and primarycable (SAE J1127 and J 1128)

8/7/2019 (SAE_BAJA_2010)

32/36

32

Thermal Protection Wire Size

8/7/2019 (SAE_BAJA_2010)

33/36

33

Voltage Drop Calculations

Resistance, R,

where A is the cross-sectional area, l is

the length, and V is the resistivity of theconductor.

A

l

R V!

8/7/2019 (SAE_BAJA_2010)

34/36

34

Voltage Drop Calculations

Resistivity at another temperature, rt,

where T is he temperature of the material,Tbase is the base temperature of the material,

Eis the temperature coefficient of electrical

resistivity, and rbase is the resistivity of thematerial at the base temperature.

? AbasebasetTTrr

! E1

8/7/2019 (SAE_BAJA_2010)

35/36

35

Steady-State Thermal Capacity

8/7/2019 (SAE_BAJA_2010)

36/36

36

Thank You