This blogs of the alternator done in practical.
With a multimeter in 2K a rotor winding to ground test was done. Test reading should be infinity. if there were a reading the rotor winding has shorted to ground and would need replacing.Then rotor winding resistance test was done. multimeter set to 200 ohms and remembering to minus the resistance of multimeter it would have to fall in between specs of 2-6 ohms.
Testing stator winding resistance each winding should have about the same resistance, multimeter also set on 200 ohms if readings are infinite or high the stator winding are open. Testing stator for ground either will be infinite or a very high resistance.
Testing rectifier positive diodes with multimeter set on diode, with common on B should give a low resistance and with positive on B the resistance should be high showing current flowing one way and not in the other.testing Now the negative diode testing, common on E should give infinite. negative test with positive on E should be a low resistance again showing that the diode are working properly which is one direction
Now test was to test regulator set point spec was 14.5v if reading is not obtained alternator would not be used because there is no output and that is what a regulator is for to regulate current output.
Last test was to measure brushes which had to be minimum of 4mm. if its under then there wouldn't be enough contact and causing sparks which would need replacing.
Thursday, 7 April 2011
Wednesday, 6 April 2011
Charging systems on car assessment
This blogs about my assessment on charging systems on car in practical.
My test was on a toyota rav4 1996 I check all connection from battery to alternator that they were connected, fuses and fusible links were checked by opening fuse fuse box under the hood and I checked the tension of the belt by pushing down on it moved down about 4mm which means belt has good tension. now I had to determine the condition of battery for the test. The battery OCV (open circuit voltage)was 12.6v. I got this reading using a multimeter. a low result would indicate that the battery is either weak or faulty. Then it was time to check the regulator, I connected multimeter to battery terminals and rev engine to 1500rpm-2000rpm and wait for multimeter to stop climbing( if it don't stop climbing the alternator isn't producing charge to charge battery) when it did it read 14.35v which is well within specs of 13.8-14.9v. If results were higher it would cause bulbs to blow. now was to determine the no load current. we turned on car and rev to 1500-2000rpm since it was fuel injected results had to be between 10-18amps and it was 15.5amps. this shows it s between specs and running like it should. if it was higher than specs it means regulator or battery is faulty. we then carried a load test on alternator,using a clamp meter around the cable running from battery to B terminal on alternator we start the car and get it to 2000 rpm with lights on and take reading of voltage and amps. Results I got was 14.1v and 51.6 amps. At 14.1v it showed it was holding voltage charge and current flow through alternator is within specs stated on the alternator. If voltage was lower then alternator wont be able to charge battery while car is running and when car starts it will not start. Now was to do a voltage drop test, using multimeter positive probe on positive terminal of battery and negative probe on alternator B terminal which should be under 0.2v. Then taking probes and putting red probe on negative of battery and black probe on alternator body and too should be under 0.2v. As long as voltage drop total is under 0.5v then both results will be within specs. If there was a high voltage drop then there is a high resistance and current is not flowing properly threw alternator.
My test was on a toyota rav4 1996 I check all connection from battery to alternator that they were connected, fuses and fusible links were checked by opening fuse fuse box under the hood and I checked the tension of the belt by pushing down on it moved down about 4mm which means belt has good tension. now I had to determine the condition of battery for the test. The battery OCV (open circuit voltage)was 12.6v. I got this reading using a multimeter. a low result would indicate that the battery is either weak or faulty. Then it was time to check the regulator, I connected multimeter to battery terminals and rev engine to 1500rpm-2000rpm and wait for multimeter to stop climbing( if it don't stop climbing the alternator isn't producing charge to charge battery) when it did it read 14.35v which is well within specs of 13.8-14.9v. If results were higher it would cause bulbs to blow. now was to determine the no load current. we turned on car and rev to 1500-2000rpm since it was fuel injected results had to be between 10-18amps and it was 15.5amps. this shows it s between specs and running like it should. if it was higher than specs it means regulator or battery is faulty. we then carried a load test on alternator,using a clamp meter around the cable running from battery to B terminal on alternator we start the car and get it to 2000 rpm with lights on and take reading of voltage and amps. Results I got was 14.1v and 51.6 amps. At 14.1v it showed it was holding voltage charge and current flow through alternator is within specs stated on the alternator. If voltage was lower then alternator wont be able to charge battery while car is running and when car starts it will not start. Now was to do a voltage drop test, using multimeter positive probe on positive terminal of battery and negative probe on alternator B terminal which should be under 0.2v. Then taking probes and putting red probe on negative of battery and black probe on alternator body and too should be under 0.2v. As long as voltage drop total is under 0.5v then both results will be within specs. If there was a high voltage drop then there is a high resistance and current is not flowing properly threw alternator.
Resisitors
This blogs of what was done in practical.
We were given six resistors and colour code chart for resistors and told to find out what its low tolerance, high tolerance and actual reading was with a multi meter in ohms and if resistors were within low and high tolerance then resistor is in working condition. On resistors are colour bands, first two or three colour bands you right down say brown,red on colour chart its 1,2.then youll have another band(3rd or 4th band) and this is how many zeros to put in multiplier say its red so its 2 which will mean 00 so this resistor would be 1200ohms. The last band is the tolarance . Tolarance is 5% to find the low and high tolarance of this resistor would be 1200 - 5% = 1.140ohms low tolarance and high tolorance would be 1200 + 5% =12.6ohms.
Then we had to pick out two resistor and connect them in series and parallel circuit, when put in parallel resistance was low because voltage is shared equally by both resistors, in series the resistance is high because resistors are connected end to end. This shows the more consumers in a series circuit restricts current flow and in parallel the more consumers the easier current flows.
We were given six resistors and colour code chart for resistors and told to find out what its low tolerance, high tolerance and actual reading was with a multi meter in ohms and if resistors were within low and high tolerance then resistor is in working condition. On resistors are colour bands, first two or three colour bands you right down say brown,red on colour chart its 1,2.then youll have another band(3rd or 4th band) and this is how many zeros to put in multiplier say its red so its 2 which will mean 00 so this resistor would be 1200ohms. The last band is the tolarance . Tolarance is 5% to find the low and high tolarance of this resistor would be 1200 - 5% = 1.140ohms low tolarance and high tolorance would be 1200 + 5% =12.6ohms.
Then we had to pick out two resistor and connect them in series and parallel circuit, when put in parallel resistance was low because voltage is shared equally by both resistors, in series the resistance is high because resistors are connected end to end. This shows the more consumers in a series circuit restricts current flow and in parallel the more consumers the easier current flows.
Tuesday, 5 April 2011
Relays
This blog is of relays we done in practical.
A relay is a output device and also known as actuator. It uses low amps circuit to switch on high amps circuit. when current flows through the low amps control circuit it generates a magneticbe field which will then turn on the high amp switch for e.g high beam of car.
We had to measure resistance between 86 to 85 while relay was off, it was 77ohms, 30 to 87a is .02ohms and 30 to 87 was 00. This shows that 86 and 85 would be low amps cause it has a high resistance were as 30 to 87a would have high amps caused by low resistance. To calculate amps it would be 12volts divide 77resistance = 0.15amps.
Relays will normally have these numbers on them 30,87,87a,85,86. 30,87 and 87a. When low amps flows through 86, 85 will ground the circuit making it whole. when this happens, 85 and 86 generate a magnetic field around coil. when switch is off 30 and 87 points would not be touching otherwise if was a 87a, it would be on. when switch goes on 30 and 87 points would connect because the magnetic field will be pulling down 30 to connect with 87 making low amps turn on high amps
A relay is a output device and also known as actuator. It uses low amps circuit to switch on high amps circuit. when current flows through the low amps control circuit it generates a magneticbe field which will then turn on the high amp switch for e.g high beam of car.
We had to measure resistance between 86 to 85 while relay was off, it was 77ohms, 30 to 87a is .02ohms and 30 to 87 was 00. This shows that 86 and 85 would be low amps cause it has a high resistance were as 30 to 87a would have high amps caused by low resistance. To calculate amps it would be 12volts divide 77resistance = 0.15amps.
Relays will normally have these numbers on them 30,87,87a,85,86. 30,87 and 87a. When low amps flows through 86, 85 will ground the circuit making it whole. when this happens, 85 and 86 generate a magnetic field around coil. when switch is off 30 and 87 points would not be touching otherwise if was a 87a, it would be on. when switch goes on 30 and 87 points would connect because the magnetic field will be pulling down 30 to connect with 87 making low amps turn on high amps
Timing resistor - capacitor circuit with voltmeter.
This blogs is about capacitors we done in practical.
Capacitor store electrical charge and prevent voltage spikes. The negative plate area provides a form of eletrostatic into which electrons can charge and this stores any form of voltage.
First was to calculate how fast th capcitor should charge. The formula was RxCx5=T
The capacitor was in uf 10 and we had to change it to F to do this I multipy by 1000 giving me 0.01then 1000 again and this was my F 0.00001. My resistance was 1000 ohms then mutiply 0.00001 to resistance multply 5 and this capacitor should take 0.05 seconds to charge. Next was to see if we could take at least 5 voltage reading in 10uf ,1uf and 100uf no time is not enough to get 5 voltage reading but 300F yes you can get 5 voltage reading from it.
We now had to figure out which capacitor would be suitable, we were given 4 capacitor a told to pick which would be suitable. To find that I look on capacitor which will have a number and uf after it e.g 330uf. When finding the number you then have to find its capacitance. You now have to multiply 1000 which will give you .330mF then multiply again by 1000 which is .00033 and this is your Farads. With the Farads you then multiply by 5 then will equal 0.00165. Then you divide by 180 because thats how long the charge test is for 180 seconds and it will give you 109.0 and that is the way to find out which capacitor would be suitable for test.
Now with the circuit board we had to build a circuit with a bridging wire was when wire was removed
the capacitor would start charging. After circuit was built every 10 seconds after disconnecting bridge wire we were to record the voltage it read for 180 seconds. When bridge wire was removed for the first 90 second the voltage climbed up rapidly, in the second half voltage started to slow because the charge that was in the capacitor is declining.
Capacitor store electrical charge and prevent voltage spikes. The negative plate area provides a form of eletrostatic into which electrons can charge and this stores any form of voltage.
First was to calculate how fast th capcitor should charge. The formula was RxCx5=T
The capacitor was in uf 10 and we had to change it to F to do this I multipy by 1000 giving me 0.01then 1000 again and this was my F 0.00001. My resistance was 1000 ohms then mutiply 0.00001 to resistance multply 5 and this capacitor should take 0.05 seconds to charge. Next was to see if we could take at least 5 voltage reading in 10uf ,1uf and 100uf no time is not enough to get 5 voltage reading but 300F yes you can get 5 voltage reading from it.
We now had to figure out which capacitor would be suitable, we were given 4 capacitor a told to pick which would be suitable. To find that I look on capacitor which will have a number and uf after it e.g 330uf. When finding the number you then have to find its capacitance. You now have to multiply 1000 which will give you .330mF then multiply again by 1000 which is .00033 and this is your Farads. With the Farads you then multiply by 5 then will equal 0.00165. Then you divide by 180 because thats how long the charge test is for 180 seconds and it will give you 109.0 and that is the way to find out which capacitor would be suitable for test.
Now with the circuit board we had to build a circuit with a bridging wire was when wire was removed
the capacitor would start charging. After circuit was built every 10 seconds after disconnecting bridge wire we were to record the voltage it read for 180 seconds. When bridge wire was removed for the first 90 second the voltage climbed up rapidly, in the second half voltage started to slow because the charge that was in the capacitor is declining.
Monday, 4 April 2011
Testing diode
This blogs about testing diode we done in practical.
first we were told to draw a picture of a diode and identify anode, cathode and current flow dircetion.
The direction of current flow is from anode to cathode.
I then had to measure resistance and position ammeter to 2K ohms and test diode from anode to cathode and cathode to anode. Both readings were both infinite.Then without changing range I checked voltage supply in my ammeter by connecting it to another and was reading 0.6V this was not enough voltage to push electrons through bindery layer because 2K was to low to turn on the diode.
Since 2K wasnt able to read anything the range was now changed to the diode setting on the ammeter and did the test again. Anode to cathode its reading was .54v and cathode to anode was infinite. These reading show that current flows through only one way because the gate will not let current go threw unless its a zenzor diode then it will bleed out excessive voltage so consumer/s dont blow.
We now had to build a circuit with a diode and resistor using a circuit board. When we had made the circuit we had to measure the voltage drop across the resistor which was 12.7V and same for across the diode which was 0.6V, then measuring amp flow through the diode which is 0.01V then measure voltage at supply which was 13.39V. Then add resistor and diode which is 13.35V. This shows in a circuit whatever the voltage supply is the consumers in the circuit have to add up to the same or voltage must be used up by consumers before returning back to battery supply. Now we had to change the resistor. The new resistor was 4000 ohms, now measuring across the resistor for voltage drop which was 12.8v then measuring across the diode and it was reading at 0.57V. I then had to measure the amps through diode which was 0.0 Amps. This indicates that the voltage is slightly up but resistor is to big for the circuit and it restricts any current flowing into the diode.
We now had to test an LED with a meter in the diode test position both ways anode to cathode 1.8v and cathode to anode 0.0v and compare its voltage drop to a diode. This shows if you need a big voltage drop, you would use a LED and if you need a small voltage drop, you use a diode.
Now we had to build a circuit with the LED. When done we measured voltage drop of resistor 11.3v then measure voltage drop of diode 2.1v then the amp flow through LED .01Amps then adding both resistor and diode result 11.3+2.1=13.4v. Comparing this circuit with the circuit with no LED, the voltage drop without LED is lower 0.6v than the circuit with the LED 2.1v and amp flow is the same in both circuits.
first we were told to draw a picture of a diode and identify anode, cathode and current flow dircetion.
The direction of current flow is from anode to cathode.I then had to measure resistance and position ammeter to 2K ohms and test diode from anode to cathode and cathode to anode. Both readings were both infinite.Then without changing range I checked voltage supply in my ammeter by connecting it to another and was reading 0.6V this was not enough voltage to push electrons through bindery layer because 2K was to low to turn on the diode.
Since 2K wasnt able to read anything the range was now changed to the diode setting on the ammeter and did the test again. Anode to cathode its reading was .54v and cathode to anode was infinite. These reading show that current flows through only one way because the gate will not let current go threw unless its a zenzor diode then it will bleed out excessive voltage so consumer/s dont blow.
We now had to build a circuit with a diode and resistor using a circuit board. When we had made the circuit we had to measure the voltage drop across the resistor which was 12.7V and same for across the diode which was 0.6V, then measuring amp flow through the diode which is 0.01V then measure voltage at supply which was 13.39V. Then add resistor and diode which is 13.35V. This shows in a circuit whatever the voltage supply is the consumers in the circuit have to add up to the same or voltage must be used up by consumers before returning back to battery supply. Now we had to change the resistor. The new resistor was 4000 ohms, now measuring across the resistor for voltage drop which was 12.8v then measuring across the diode and it was reading at 0.57V. I then had to measure the amps through diode which was 0.0 Amps. This indicates that the voltage is slightly up but resistor is to big for the circuit and it restricts any current flowing into the diode.
We now had to test an LED with a meter in the diode test position both ways anode to cathode 1.8v and cathode to anode 0.0v and compare its voltage drop to a diode. This shows if you need a big voltage drop, you would use a LED and if you need a small voltage drop, you use a diode.
Now we had to build a circuit with the LED. When done we measured voltage drop of resistor 11.3v then measure voltage drop of diode 2.1v then the amp flow through LED .01Amps then adding both resistor and diode result 11.3+2.1=13.4v. Comparing this circuit with the circuit with no LED, the voltage drop without LED is lower 0.6v than the circuit with the LED 2.1v and amp flow is the same in both circuits.
Sunday, 3 April 2011
Charging systems on car testing
This blogs about about alternator output on car testing.
Before working on the motor, brake had to be applied and put in neutral if its a manuel or park if its automatic.
I then done my preliminary checks of charge warning light which wasnt on indicating charging system is producing enough current for electrical needs of car. Ignition and all accessories were off, if it werent then it will drain my battery. Visual inspections were done of connections to make sure they were all connected cause if they werent then there would be break in the charging circuit. Fuses and fusible links were check if any were blown and none were, if they were it sub electrical wouldnt be supplied with voltage. I also checked the charging system drive belt. I pushed down on it and it moved down 4mm which means it a good tension.
A no load test was now to do, I first did a OCV on the battery. That reading was 12.5V (75%) now its to do a regulator voltage test. The specs for regulator voltage test is 13.5V-14.8V. I used a voltmeter, put positive probe on positive terminal of battery and negative probe on negative terminal, then reving car to 1500-2000rpm the meter will then reach a point and no longer rise that will be the reading which was 13.9V which is well witth in specs. Then I did amps test to see how much amps the regulator was putting out of the alternator. This reading was 11.3Amps, because it was a carburettor motor it was within specs which was 5-12Amps. With these readings the regulator was working within spec of a no load test.
Now to do test with load on. To figure out my base voltage I had to add 0.5 to my OCV(125V). This gives 13V as my base. Voltmeter was set to 20V DC and clamp induction meter was set to 400Amps DC, I got a mate to rev engine to 1500-2000rpm and turn all accessories on. I put my voltmeter on battery and clamp meter around main output wire. These reading were 52Amps and 13V. The current output was good charging voltage under load was the same as my base voltage which is the minimum you can have if it were lower it would mean alternator will not be charging battery while all accessories are all on and battery will discharge within a day or two depending on battery.
Now was to check voltage drop, I put voltmeter positive probe on battery positive post and negative probe to alternator output , this was 0.5 volt drop then positive probe on negative post to body of alternator, this was 0.2 volt drop total was 0.7 volts drop. The reading from battery positve to alternator output wasnt with specs which made total volt drop of 0.7 vd, but then I took load off and 0.5 vd became 0.2 so with load off it does fall into specs, but regulator would still need looking at to replace or reconditoned.
Before working on the motor, brake had to be applied and put in neutral if its a manuel or park if its automatic.
I then done my preliminary checks of charge warning light which wasnt on indicating charging system is producing enough current for electrical needs of car. Ignition and all accessories were off, if it werent then it will drain my battery. Visual inspections were done of connections to make sure they were all connected cause if they werent then there would be break in the charging circuit. Fuses and fusible links were check if any were blown and none were, if they were it sub electrical wouldnt be supplied with voltage. I also checked the charging system drive belt. I pushed down on it and it moved down 4mm which means it a good tension.
A no load test was now to do, I first did a OCV on the battery. That reading was 12.5V (75%) now its to do a regulator voltage test. The specs for regulator voltage test is 13.5V-14.8V. I used a voltmeter, put positive probe on positive terminal of battery and negative probe on negative terminal, then reving car to 1500-2000rpm the meter will then reach a point and no longer rise that will be the reading which was 13.9V which is well witth in specs. Then I did amps test to see how much amps the regulator was putting out of the alternator. This reading was 11.3Amps, because it was a carburettor motor it was within specs which was 5-12Amps. With these readings the regulator was working within spec of a no load test.
Now to do test with load on. To figure out my base voltage I had to add 0.5 to my OCV(125V). This gives 13V as my base. Voltmeter was set to 20V DC and clamp induction meter was set to 400Amps DC, I got a mate to rev engine to 1500-2000rpm and turn all accessories on. I put my voltmeter on battery and clamp meter around main output wire. These reading were 52Amps and 13V. The current output was good charging voltage under load was the same as my base voltage which is the minimum you can have if it were lower it would mean alternator will not be charging battery while all accessories are all on and battery will discharge within a day or two depending on battery.
Now was to check voltage drop, I put voltmeter positive probe on battery positive post and negative probe to alternator output , this was 0.5 volt drop then positive probe on negative post to body of alternator, this was 0.2 volt drop total was 0.7 volts drop. The reading from battery positve to alternator output wasnt with specs which made total volt drop of 0.7 vd, but then I took load off and 0.5 vd became 0.2 so with load off it does fall into specs, but regulator would still need looking at to replace or reconditoned.
Battery testing assessment
This blogs about my battery assessment a done in practical.
We were given the assessment and told to start. First I determined CCA of the battery which is 410CCA. Then perform a visual check of battery looking for corrosion around on terminals and swelling at the end of battery. There was no visual signs of the battery requiring any futher attention.
I then check the electrolyte levels of the battery. All six cells were OK which meant electrolyte levels good, if they werent then they would need topping up with distilled water.
Next was to check OCV of the of the battery my first was 12.9V, I had to get rid of the surface charge so I swicth on the fan and it brought it down to 12.5V which is 75% charge.
Then I proformed a specific gravity test. Cells 1,2,4,5,6 were all 1.300 and cell 3 was 1.290 which gave me a variation of 10 which is within specs of 0-25 and 25-50 depending on books.
Next was to determine the load current to apply for a high discharge rate test, my battery was 410CCA so I had to apply half which is 205Amps and must hold over 9.5V for about 15 seconds. The voltage with load was 12.7V and load current was 10.2Amps. All readings fell within specs which makes this battery ready to be given back to the customer.
We were given the assessment and told to start. First I determined CCA of the battery which is 410CCA. Then perform a visual check of battery looking for corrosion around on terminals and swelling at the end of battery. There was no visual signs of the battery requiring any futher attention.
I then check the electrolyte levels of the battery. All six cells were OK which meant electrolyte levels good, if they werent then they would need topping up with distilled water.
Next was to check OCV of the of the battery my first was 12.9V, I had to get rid of the surface charge so I swicth on the fan and it brought it down to 12.5V which is 75% charge.
Then I proformed a specific gravity test. Cells 1,2,4,5,6 were all 1.300 and cell 3 was 1.290 which gave me a variation of 10 which is within specs of 0-25 and 25-50 depending on books.
Next was to determine the load current to apply for a high discharge rate test, my battery was 410CCA so I had to apply half which is 205Amps and must hold over 9.5V for about 15 seconds. The voltage with load was 12.7V and load current was 10.2Amps. All readings fell within specs which makes this battery ready to be given back to the customer.
Starter motor on car assessments
This blogs about my on car assessment of a starter motor in practical.
I went to practical and we were given our assessment. First it said to do a preliminary check, so I de-activated the ignition, then checked if battery was useable, check if meter was in the right range and see if it was in neutral. All was good so I procced.
It was now time to check voltage under cranking. It gave me a reading of 12.4V which is 50% chargeso battery passed. Now checked the starter circuit for voltage drop. I put my positive probe on battery terminal of the positive and negative on the battery terminal of the solenoid which read 0.2vd, then battery terminal of solenoid to motor terminal of solenoid which read 0.2 and battery negative terminal to body of starter motor it read 0.2vd. If I had cranked the engine while doing these test my reading would have been different thats why it was higher than maximum allowed which is 0.5vd.
Then it was time to do a starter draw test. The specs for this test is 125Amps-175Amps. I got the clamp meter and clamped the lead running from the positive terminal of the battery to the battery terminal of the solenoid and it gave me reading of 150Amps. This had fallen within specs and passed.
The test was good but I forgot to crank the engine while doing voltage drop test of the battery to solenoid and therefore only got a 5/10. Wont forget again.
I went to practical and we were given our assessment. First it said to do a preliminary check, so I de-activated the ignition, then checked if battery was useable, check if meter was in the right range and see if it was in neutral. All was good so I procced.
It was now time to check voltage under cranking. It gave me a reading of 12.4V which is 50% chargeso battery passed. Now checked the starter circuit for voltage drop. I put my positive probe on battery terminal of the positive and negative on the battery terminal of the solenoid which read 0.2vd, then battery terminal of solenoid to motor terminal of solenoid which read 0.2 and battery negative terminal to body of starter motor it read 0.2vd. If I had cranked the engine while doing these test my reading would have been different thats why it was higher than maximum allowed which is 0.5vd.
Then it was time to do a starter draw test. The specs for this test is 125Amps-175Amps. I got the clamp meter and clamped the lead running from the positive terminal of the battery to the battery terminal of the solenoid and it gave me reading of 150Amps. This had fallen within specs and passed.
The test was good but I forgot to crank the engine while doing voltage drop test of the battery to solenoid and therefore only got a 5/10. Wont forget again.
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