Health and safety puzzle

Testing an alternator

How to check if the alternator give off a charge


Connect a voltmeter in parallel between the negative terminal of the battery or on the body(ground) and the (B+) wire on the alternator this should give a reading of the voltage that is produced

What checks to do before testing

• visually inspect the wiring for any loose connections or corrosion
• check the tension of the belt that drives the alternator and its condition (should not have cracks)
• check to see that the charging light comes on when the car is switched on
• check the alternator bracket 
• visually inspect the alternator its self for any obvious damage or if any oil has leaked on to it

Testing the voltage drop

Before testing start the engine

To test the voltage drop connect the multimeter with the com wire to the negative terminal of the battery and the positive wire to the body of the alternator. To check the positive voltage drop connect the com wire to positeve terminal on the battery and the positive wire to the B+ terminal.

SCR / Thysistor

How a battery works 08/03/2012

Components

• Chemical bath (65% distilled water  H₂O , 35% sulphuric acid  H₂SO₄)
• Cells
• Plates covered in lead (negative)
• Plates covered in lead oxide (positive)
• Negative terminal 
• Positive terminal
• Casing

Function

• The chemical bath acts as an electrolyte (a substance that conducts electricity)
• The battery has six cells that contain 2 electrodes each. one is positive the other is negative.There are16 individual plates in the cell that form a grid.
• Each cell produces between 2 and 2.1 volts. They are connected in series which gives the battery an overall percentage of 12 -12.6V
• The electrons flow from the positive plates (covered in lead oxide) through the chemical bath to the negative plates (covered in lead)
• The casing holds the chemical bath
• The positive terminal draws electrons in and the negative pushes the electrons out

Health and safety exercise 08/03/2012

The Law


Both the employer, Unitec Institute of Technology and its students have statutory obligations under the health and safety in employment act 1992 and all its amendments.

Employer Duties Include:


To take all practicable steps to:
 Provide a safe working environment, Provide procedures for dealing with emergencies
Provide facilities for staff that include toilets and rest rooms, also First Aid facilities.
Employees receive appropriate training in all matters

Students Duties include


Taking responsibility for your own safety and health at work
ensuring that your action or inaction does not harm others
reporting all injuries or near hits to your supervisor as soon as possible after the event.

Hazards


To help reduce the health and safety risks in our workplace we need you to report any hazards that you may identify that have the potential to cause injury or serious harm
Report the problem to your supervisor immediately so that the risk can be analysed and preventative action taken
Who is your Health and safety representative Rob Humphreys

Battery Testing 07/03/2012

Checking if the battery is OK

1. Check what the voltage is across the terminals of  the battery. It should be around 12.6V
2. If the voltage is low charge it up. When the battery is completely flat charge it with a trickle charger for about 22 hours then it should be fully charged
3. Connect the battery to a battery test and turn up the amps to that of the starter to see if the battery can handle it. If the battery can't handle it then it needs to be replaced

Checking if the battery charges 

1. Find the voltage of the battery when the car is off
2. Start the car and check the voltage again. It should be between 13.2 and 14.4V. If the voltage is lower than this it means there may be a fault with the alternator or the wiring. If the voltage stays the same (12.6V) then it means the alternator is not charging the battery
3. Switch on a few applications such as the lights, radio,wipers etc. to check if the alternator can handle it and  still charge the battery. (have a volt reading of 13.2 - 14.4V)

Checking for a current draw

1. If the battery is fine then use an ammeter to see if any current is drawn from the battery while the car is switched off.
2. make sure the car is switched off
3. set the ammeter to amps and connect the wire to the right port
4. remove the negative wire from the terminal
5. connect the ammeter in series to the cars circuit (between the battery cable and the terminal)
6. the reading should be close to zero. If not then something is drawing current from the battery
7. to find out what it is remove the fuses individually and check the ammeter reading until the reading is zero when a fuse is removed
8. check the diagram to find the application the fuse belongs to and find out why it is drawing current

LED probe 01/03/2012

LED test light

Components

• LED x 2
• Brass rod
• Wire x 2
• Soldering
• Resister x 2
• Heat shrink

Function

The wires are conductors, the carry the power from the power source through the resistors to the LEDs

The resistors protect the LEDs from high voltages

LEDs (light emitting diode) are diodes so they only allow the current to pass through them in one direction they also work as indicators to show that there is a voltage present. LEDs are also used because they use a low voltage that will not damage components that use low voltages like computer systems

The brass rod acts as a conductor carrying the power from the component being tested to the other terminals of the LEDs

The soldering is a conductor that permanently connects the components together

Heat shrink is an insulator used to cover the components to protect them from a short circuit

Usage

The probe is used to check if there is power at a certain point and if it is positive or negative. The LEDs only allow the power to go in one direction therefor if the green light goes on it indicates that the tested component is positive and if the red goes on it is negative.