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Old 06-02-2022, 01:39 PM   #7 (permalink)
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Join Date: Jan 2009
Location: Macon,GA
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Ruint Taco - '19 Toyota Tacoma SR Double Cab
90 day: 23.76 mpg (US)
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Originally Posted by Piotrsko View Post
If the alternator is spinning it will contribute to engine drag, even unloaded. @ 3mpg it isn't noticeable, but as you get higher in the distance per volume of fuel it becomes apparent. You may not ever see it, but your electrical system has a cold function so you may need to trick it even at 14.1v. I suggest a disconnect switch of some sort

Yes, on most modern cars, the ECU raises the output voltage to 14.1-14.6 for a short period after starting, this to quickly replaced energy that was used to start the car.

Even though the battery is hit with this higher voltage, the current will be very low, because the starting battery will be fully charged from the lithium battery. The internal resistance on a fully charged battery is high, so the current flow will be low.

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