draw on battery?
Thread Starter
TECH Regular
Joined: Nov 2004
Posts: 440
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From: league city,tx
draw on battery? Any help is appreciated...I seem to have a draw off of my battery but can't figure out how. I have replaced my battery but after a few days this one went completely dead as well?! Lights and everything else works fine and I waited to make sure that the 'child feature' goes out after the car has shut down. Could it be a ground? I've already checked all of the fuses-nothing is blown. Any suggestions?
TECH Apprentice
Joined: Feb 2005
Posts: 384
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Buy yourself a digital multimeter and see what kind of amperage draw is actually there. (disconnect negative battery terminal, and put the + and - leads between the cable and battery post -- with the meter set to DC amps).
Once you find out what kind of draw is on the battery, thus verifying that this isn't a charging system problem, you can then start pulling fuses one-at-a-time as you watch the DVOM. When the amperage draw decreases, you've found the trouble circuit.
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I believe the goal is to hit roughly 30-50 milliamps. Using this method, I found out my car has a 75 mA draw, because the idiot that installed my sub/amp didn't use a switched power source. If I unplug the fuse for the sub/amp, the amperage draw will drop to about 35 mA (right where I want it). I'll have to wire in a relay for it now.
As for another example, my roommate's car has a huge draw coming from his alarm. He's well into the 100+ mA range. Talk about a pathetic aftermarket alarm system. Its anti-theft feature is to drain the battery so nobody can drive away with it...
Once you find out what kind of draw is on the battery, thus verifying that this isn't a charging system problem, you can then start pulling fuses one-at-a-time as you watch the DVOM. When the amperage draw decreases, you've found the trouble circuit.
---
I believe the goal is to hit roughly 30-50 milliamps. Using this method, I found out my car has a 75 mA draw, because the idiot that installed my sub/amp didn't use a switched power source. If I unplug the fuse for the sub/amp, the amperage draw will drop to about 35 mA (right where I want it). I'll have to wire in a relay for it now.
As for another example, my roommate's car has a huge draw coming from his alarm. He's well into the 100+ mA range. Talk about a pathetic aftermarket alarm system. Its anti-theft feature is to drain the battery so nobody can drive away with it...
Last edited by Alex94TAGT; Mar 2, 2005 at 06:48 AM.
