Battery, Alternator and Starter On Car Testing

My car was used for battery and alternator testing it is a
1991 Toyota Corolla AE92.

Battery Testing


Today I completed the on car testing workbooks. I used my cars battery for the testing and from the various tests I concluded that it was in good working order. Testing that was done Involved using a Multimeter, load tester and digital battery tester.


Multimeter was used for:
  
Obtaining open circuit voltage (OCV): This was done by first removing surface charge on the battery, by turning on the head lights for 1 minute, with meter connected across terminals (reading should fall). Then after turning the headlights off checking once again with meter on DC voltage until reading stops rising. When I checked I got a reading of 12.65V which indicated a 95% charged battery which was good.  


Finding Parasitic Draw: This was done by connecting the meter in series on Amp setting by disconnecting negative battery terminal and adding the meter with positive lead (Red) on negative lead and meter negative lead (black) on negative battery terminal. This is used to find out how much charge is being used by accessories when car is not running. The tested battery showed a reading of 2.62mA being used. So it was well within correct range which was 35mA or less.   


Load Tester was used for: Determining the batteries ability to provide cranking voltage. It required you to find out what load current was required which for my battery was 215CCA as my batteries normal CCA (cold cranking amps) was 430CCA Correct voltage was found by 430/2=215. When tested the reading on the voltage was 10V which was correct for the battery.


Digital Battery Tester was used for:  Instead of doing all the above tests as it obtains all readings in the same unit and is much easier to use and obtain readings. 

Picture of Digital Battery tester similar model to what I used today

When I tested my battery I had to change the rating on the tester to 430CCA and then push the "test" button. It completed the test and stated on the screen that the battery was a PASS. It also found the OCV which was 12.71V and the current CCA which was 400CCA Which meant that the battery was fully charged and in good working order.

Alternator On Car Testing

Alternator that was checked

I did this using the alternator of my car and by using a Multimeter set to volts and a Clamp meter to obtain the current moving through a conductor from the battery to alternator.

When checking the alternator voltage regulator I found that it was working correctly it showed on my meter a reading of 14.5V which meant that the voltage regulator was working correctly. This is checked by turning the car on and then letting it run, while running I put the multimeter across the positive and negative battery terminals and then recorded the reading.

For the next part the clamp meter was used to get the no load amps this was done by putting the clamp around the main lead to the alternator and then recording the reading which was 13.6A which was also correct Indicating It was in good order.

Starter On Car Testing


This required testing of the various circuits of the starter motor while engine was cranking to determine voltage drops.

• First area tested was loss between the batteries positive terminal to the starter solenoids input stud. Got a reading of 120mV 
• Second was across both of solenoids studs which also got 120mV 
• Third was between positive battery terminal and the starter motors body which got 111mV 
• The maximum voltage drop was 351mV this was determined when earlier readings were added together 

From these readings I found that the starter motor was also in good condition as none of the maximum voltage levels were exceeded meaning that no repairs or replacements required.