another not charging thread

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Tylan said

I had put both the negative clamp AND the jumper wire on the negative post, just to clarify, and then I took off the negative clamp WITH the jumper wire still on the post and engine kept running.

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Ok. That makes sense

Mattax said

For current to flow it needs a complete circuit.

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The power circuit looks like this:


If the system was being powered the battery, the current flows from the battery positive to the negative.
The current path to the ignition is marked with orange arrows. The ECU, coil and spark plugs all connect to ground. Ground connects to the battery negative post.



The amount of flow is called current.
The ammeter should show a couple of amps flowing out of the battery to power the ignition.
The voltage of the current should still be 12.5 Volts when it gets to the ballast resistor.
Any loss of voltage indicates resistance in the path of the current.

The same goes when the alternator is supplying power. Even if its running poorly.
The circle is completed like this.