12v consumption

Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=105183
Printed Date: May 05, 2025 at 11:12 PM

Topic: 12v consumption

Posted By: mrconcept
Subject: 12v consumption
Date Posted: June 01, 2008 at 9:49 PM

I'm trying to find a way to know if I put one 55W fog light on a 12v batterie that as 18 amps/hour how long is the light going to last if the battery is not recharged will the motor runs. Thank's for your answers.

MR Concept

Replies:

Posted By: Big Dog
Date Posted: June 04, 2008 at 2:42 PM

The short answer: max 4 hours (non linear obviously). Usuable might be 2 hours.

The long answer:

R=V^2 / W

R=144 / 55

R=2.62 ohms

Thus . . .

I=V / R

I=12 / 2.62

I=4.58

18 / 4.58 = 3.93 hours

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Prepare your future. It wasn't the lack of stones that killed the stone age.

Posted By: mrconcept
Date Posted: June 04, 2008 at 7:09 PM

Thanks it's really appreciated

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