Teach me about battery specs (non-OEM/ replacement battery research)

[Howie]

OK, I'll try and explain it without a blackboard.  Voltage drop is the best way to test for resistance in a working, live circuit.  Resistance from corrosion can build with heat, so an ohm meter may not pick up the problem.

Voltage drop is the amount of voltage consumed by a conductor, connection, switch or consumer.  An example of a conductor is a wire.  I think switch and connection are obvious enough.  A consumer is something that uses electricity like a bulb or motor.  

Voltage drop is measured by placing the volt meter in parallel with the component you are testing.  This is where a blackboard would be handy, but here goes:

                               voltmeter
                              l             l
________+                l             l                                                  -
l Battery  l------------l---bulb---l---------------------------------ground
l________l

In this piss poor drawing I would be be measuring the voltage drop of the bulb.  

Ideally, the voltage drop of a conductor or connection should be zero.  What is considered acceptable as a general spec in the automotive world for a starter circuit is .1 volts for any wire, connection or switch, and .5 volts for the solenoid.  The tests must be made while cranking the engine.  Remember, battery terminals, the starter connection and the engine ground are connections.  Hope this helps.  If someone can provide a better drawing or drawings, please do!

Again, I agree with ducatiz.  Without the proper tools it is difficult to properly swedge the terminals to the wires.  Poor installation of the terminals creates a perfect environment for corrosion.
 

[erkishhorde]

So if I'm checking the cables I changed, 1 end of the voltmeter goes on each end of the cable, right?

[Howie]

Correct!

[Speeddog]

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