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parasitic power loss?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=64152
Printed Date: July 06, 2025 at 1:27 PM


Topic: parasitic power loss?

Posted By: JIMMY 2 TIMES
Subject: parasitic power loss?
Date Posted: October 10, 2005 at 3:39 PM

if is run my car everyday, there is never a problem, now if if sits for a few days, good luck. I have only added a deck and an amp, and this is not the problem, (checked with DMM).

Now, how would i go about finding where the draw is coming from? I was told about using a small 12v bulb, and going from there. Can someone please elobrate on this more for me?

thanks



Replies:

Posted By: auex
Date Posted: October 10, 2005 at 3:46 PM
Or how about you replace what is probably a battery going bad???

Pull the ground from the battery, make sure all doors and anything that can draw power is off(so you don't blow the meter's fuse, so no domelights and no ign), set meter to mA, place meter in line with - terminal and the battery, walk away for 30 minutes, come back and get the reading. If the measurement is more then 50mA then something is drawing current. But even at this low a draw it would still take more then 2 or 3 days on a GOOD battery.

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Posted By: ice8168
Date Posted: October 10, 2005 at 4:52 PM

From a technician stand point there are a few thing to consider when doing a closed circuit current measurment (parasitic draw) test.

First, the meter must be hooked up in series, but you must be careful when beginning the measurment not to blow the fuse.  As auex stated all the loads in the vehicle must be off.  However,  if you do see a draw of over 50mA after 30 min to 1 hr. you dont want to have to open the doors to get to fuses and different components.  So in that case leave all the door and trunk open, but latch all the latches to simulate the doors being closed.  If you do have a draw start pulling fuses to eliminate different circuits.  When the draw goes away you've found the circuit that is causing problems. 

Also, be careful on some later GM vehcile as some of them have an after-blow feature to keep the evap core dry.  This causes the blower to kick on at different times.  This will blow the mA fuse in your meter.  Also keep in mind that if for some reason your meter looses connection this will open the circuit and upon reconnection some modules will be woken up causing possible false draw mearurment.






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