Hans' battery questions

1. What is a battery?
- A car battery is a physical reserve of energy within the car system. The battery is usually charged by an alternator — a device that converts the mechanical energy from the engine into electrical energy.

2. How does it work?
- A car battery works by producing an electrical charge via a chemical reaction inside the battery, which is then sent through wires to power the starter, the lights, radio, and any other electrical components.


3. Components of a battery.
- Car batteries provide a nominal 12-volt potential difference by connecting six galvanic cells in series. Each cell provides 2.1 volts for a total of 12.6 volt at full charge.


4. How do you test a battery?
- Attach a voltmeter to the battery to measure the voltage. To do this you attach the positive lead of the voltmeter to the positive terminal of the battery and the negative lead the negative terminal of the battery. The voltage should be around 12.5 - 12.8 volts, this means that it is 100% charged.


5. What do you test before changing the battery?
- You check to see if the battery is fully charged and the terminals are clean/ are not loose.
- Check for current draw while the car is off.

Starter Motor Testing

Before you test the Starter motor, you have to check to make sure that the battery is clean e.g. the terminals are not rusted or corroded.

After that, you check if the battery is charged. To do this, you connect a voltmeter to the terminals. 12.6/7 Volts means that the battery is fully charged. Then, you disconnect the distributor so that the car won't start. Turn the key and the voltage should drop to around 10 - 11.

Next, you check how many amps are flowing from the battery to the starter motor. You do this by putting an amp reader over the cable that leads from the battery to the starter motor, it should read under 175 amps.

To check the voltage drop from the battery to the starter, you connect the positive wire to the starter motor and keep the negative wire on the negative terminal. Voltage drop should be roughly  0.2 Volts.

To measure the voltage available at the starter motor you subtract the voltage drop from the amount of volts that the car is putting out. For example, if the car was putting out 11.2 Volts and there was a drop of 0.2 Volts, your voltage available would be 11 Volts.

For the amount of volts to the ignition terminal on the starter motor, you connect the positive wire to the ignition terminal and the negative wire to the negative terminal on the battery.

Lastly to check the voltage drop through the negative terminal of the battery, you keep the negative wire on the negative terminal of the battery and connect the positive the wire to the engine block. The voltage drop should be around 0.2 - 0.3 volts.

How to test a battery

To test a battery, you first turn the lights on for about a minute to see if the battery holds it charge. After that you connect the multimeter to the positive and negative terminals of the battery, and set it to volts. If the voltage reads 12.6 volts it means that it's 100% charged. 12.2 volts means 50% charged and 11.9 volts means that the battery is not charged at all. If the battery is charged, you turn the car on and turn the lights and other things inside the car to make sure that the voltage stays around 14 - 14.5 volts. (this means that the alternator is working correctly.)


This video gives a good step by step guide on how to do this:
http://www.youtube.com/watch?v=Bzz7P3qNHcE 

To check if there is any current being drawn from the car, you link the battery into series with the multimeter and set it to amps. To do this you take the clamp off the negative terminal and touch the positive wire (the red one) to the clamp and the negative wire (the black one) to the negative terminal of the battery. It should read 0.01 amps (or around there), this means that there is nothing drawing current from the battery while the car is off.


This one shows you how to check for Current Draw:
http://www.youtube.com/watch?v=MNzZSsuQthY&feature=related

Battery

What an Automotive Battery is:
An automotive battery is a type of rechargeable battery that supplies electric energy to an automobile. Usually this refers to an SLI battery (starting, lighting, ignition) to power the starter motor, the lights, and the ignition system of a vehicle’s engine. 


Components of a Car Battery:
12v batteries have 6 galvanic cells, each providing 2.1 volts for a total of 12.6 volts (battery at 100% charge).

The Red knobs on the top are the 6 cells that provide 2.1 volts each.
Lead-acid batteries are made up of lead plates and separate plates lead oxide which are submerged by an electrolyte solution of about 35% Sulfuric Acid and 65% Water. This creates a chemical reaction which allows the conductors to produce electricity.


Putting on and Taking off a Car Battery:
When taking a car battery off, it is very important that you take off the negative terminal first. This will stop the circuit, meaning that when you take off the positive terminal there will be no voltage flowing through it. The Negative terminal is Black and the Positive terminal is Red, the red cover on the positive terminal is a good indicator that it is dangerous. To put the battery back on it goes the other way (Positive on first, negative on next).

As you can see, there is a bright red cover over the positive terminal.

Thyristor

A thyristor is a solid-state semiconductor device with four layers of alternating N and P-type material. They act as bistable switches, conducting when their gate receives a current trigger, and continue to conduct while they are forward biased.

This is a diagram of a Thyristor fired Coil gun circuit.

This video offers a great explanation of what a Thyristor is:
http://www.youtube.com/watch?v=v58KiktJLyE&feature=related

Headlight Diagram

Components:
- Battery
- Wire
- Fuse
- Relays x2
- Headlight Bulbs x2
- Switch


Function:
The battery supplies the power. The wires carry the power through the fuse to terminal 30. The relays function as a remote switch, the main current flows from the battery to the user or the headlight bulb. The terminal number is generally 87 of 87a.
It is activated by a low current coil that acts as a magnet to close the switch. Terminal numbers are 85 and 86. terminal 85 goes to earth or ground source. Terminal 86 supplies power through a switch to complete the circuit.

How to make a Test Light

To make a test light, you need these components:
- Brass Rod
- Red and Green LED's
- Red and Black wiring (2 meters long)
- 2 resistors
- Red and Black alligator clips
- 7 mm plastic tubing
- 2.4 mm Black shrink tubing
- 6.4 mm Red shrink tubing
- 12.7 mm Black shrink tubing


Firstly, you have to cut the ends of the red and black wire casing off to expose the wires inside (Refer to picture 3). After that you need to solder the resistors to the wires and then solder the LED's to them. Secondly, you have to insulate the brass rod with the 2.4 mm Black shrink tubing. Leave a gap in the middle for the LED's to be soldered onto the brass rod. Once you've done that, you solder the LED's onto the brass rod. Next, you wrap the red and black wires together so it will be easy to fit the 7mm plastic tubing, the 6.4 mm Red shrink tubing and the 12.7 mm Black shrink tubing on over it. Then, to make it look nice at the end you place the 7 mm plastic tubing over the brass rod and up to the LED's. To keep this in place you heat shrink the red and black tubing on.

This is an example of a finished Test Light

This is a close up picture of LED's

This is a close up of the ends of the wire casing cut off to expose the wires inside

How to measure Volts and Amps on a car battery

To measure the Amperage in a car battery you must first disconnect the negative terminal. After that, you set the multi meter to 10A. Then you must connect the points of the multi meter to the negative terminal of the battery to find the amps flowing through the battery.


To measure the Volts in the battery, you must connect the negative terminal back onto the battery. After this, set the multi meter to DC (direct current). Then connect one of the wires of the multi meter to the positive terminal and one to the negative terminal to find the volts going through the battery.

Ohms Law and Health and Safety

Today we learnt the basic Health and Safety practices for in and around the workshop. For example, the clothing requirements for the workshop (safety boots and over-all's). These requirements are in place to protect us and keep us safe in the workshop.


We also learnt about Ohm's law, this is used to find out things such as Voltage, Amperage and Resistance. For example, to find Amperage, you divide the Ohms from the Voltage (12v\6 ohms = 2 Amps.


This video explains Ohm's Law well,
http://www.youtube.com/watch?v=QwNSa_8ro_Y