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<blockquote data-quote="maylar" data-source="post: 7791694" data-attributes="member: 541144">We agree on something then. And that&#039;s why I said you can &quot;theoretically&quot; remove the battery once the engine is running. In practice that&#039;s a bad idea because the battery absorbs transients.That was true in the old days. Under heavy load at idle the battery would supply some current because the alternator couldn&#039;t keep up. Voltage would drop to 12.5V. But modern charging systems do indeed have the ability to supply almost full rated current at idle speeds. Put an amp clamp on your alt wire sometime and see for yourself. Look at it this way - if the voltage is above 12.6V then the alt must be supplying all of the current.There&#039;s where we disagree. My point is that the alternator and battery are electrically the same, separated by a length of wire. In the OP&#039;s case the wire is just longer than usual. But the voltage source is the alternator as long as the engine is running. It makes no difference which end of the wire you connect to. With engine off, that long wire would be significant but no different than running a wire from battery to the trunk in a &quot;normal&quot; install.</blockquote>

[QUOTE="maylar, post: 7791694, member: 541144"] We agree on something then. And that's why I said you can "theoretically" remove the battery once the engine is running. In practice that's a bad idea because the battery absorbs transients. That was true in the old days. Under heavy load at idle the battery would supply some current because the alternator couldn't keep up. Voltage would drop to 12.5V. But modern charging systems do indeed have the ability to supply almost full rated current at idle speeds. Put an amp clamp on your alt wire sometime and see for yourself. Look at it this way - if the voltage is above 12.6V then the alt must be supplying all of the current. There's where we disagree. My point is that the alternator and battery are electrically the same, separated by a length of wire. In the OP's case the wire is just longer than usual. But the voltage source is the alternator as long as the engine is running. It makes no difference which end of the wire you connect to. With engine off, that long wire would be significant but no different than running a wire from battery to the trunk in a "normal" install. [/QUOTE]

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