How to Diagnose a Battery Drain

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Dec 31, 2024 | 02:10 AM

#21 (permalink)

M60A3Driver

Senior Member

Joined: May 2023

Posts: 2,973

Likes: 1,564

From: New Jersey

Re: How to Diagnose a Battery Drain

Quote:

Originally Posted by Capt_TJM

My high school shop teacher showed me the voltage drop technique on the old style glass BUSS fuses about 40 years ago. He had this big phenolic resin Westinghouse analog needle amp meter with ***** and multiple scales. My first intro to Ohms Law and the basics that still hold true today.
I am stumped by a steady 0.180 Amp drain on a 2005 Crossfire. A 1 year old battery is dying in less than 2 weeks, not totally dead but that awful clicking only sound when trying to start. I did the voltage drop method across all fuses and found that fuse 9, dome light, anti-theft module fuse would drop the steady drain to .130 or so. I'm assuming that is the NIL of 0.050 that should be there. I've checked the 50 and 200 Amp fuses, all good. Tomorrow I'll check your number 11 step, the alternator big red and hope that does it. ** I put in a re-manned alternator about 2 years and 7,000 miles ago. I used low price as my choice, I guess I got what I paid for. ** I hooked up a NAPA newer battery tender I've used on other vehicles but when switched to on, the "reversed polarity" light comes on, only on the Crossfire. I'm hoping a bad diode is the culprit and a quality alternator will solve the problem. If not, step 12, vehicle was stolen! Your posts have saved me from going down some rabbit holes. Thank you.

The most common power drain is the alarm siren which is located in the center of the car under the windshield cowl. Another common drain is the factory radio.
If you haven't disconnected or replaced the alarm siren, I would suggest doing so no matter what.
Here is a post that I did explaining how to replace the alarm siren and clean the drains while you have the wiper cowl off.
The post is in 2 parts because of picture limitations. I hope that you will find this useful.

LINK to alarm replacement & drain cleaning part 1

LINK to alarm replacement & drain cleaning part 2

Dec 31, 2024 | 02:05 PM

#22 (permalink)

pizzaguy

Administrator

Joined: Jun 2009

Posts: 13,932

Likes: 1,266

From: Fort Worth, Texas

Re: How to Diagnose a Battery Drain

Quote:

Originally Posted by Capt_TJM

1) My high school shop teacher showed me the voltage drop technique on the old style glass BUSS fuses about 40 years ago.

2)I am stumped by a steady 0.180 Amp drain on a 2005 Crossfire.

The reason for item 2 is in item 1.

Your shop teacher meant well, but unfortunately, he lacked the expertise to understand how wrong he was. Speaking as a 30 year electronics technician, I can tell you that inserting an ammeter in line is the ONLY way to know what current is flowing.

Simply follow my procedure and in less than 1/2 hour, you will know what current is flowing and where it is flowing. PERIOD.

Taking these lazy shortcuts wastes time. No actual technician who understands what he is doing measures voltage drop across a damn FUSE to track a fractional amp of current. MY SE's standby current is .015 to .019 amp. I can leave the car in the garage for eight weeks and it starts right up, every Crossfire on the road should be the same. I can even tell you where that .019 amp is going, because, out of curiosity, I have measured it. (PTCM, SKREEM, AM/FM head and the CLP/SSM together sink .018 amp.) Such precision by measuring voltage drop across a fuse is impossible.

Go measure the current and if you need help with putting a stop to the excess current, just post (tag me tho) and I will be happy to get you thru this.

Happy new year!

Dec 31, 2024 | 06:32 PM

#23 (permalink)

Capt_TJM

Joined: Dec 2024

Posts: 3

Likes: 0

From: CT

Re: How to Diagnose a Battery Drain

PIZZA GUY, Thanks for the input. I re-grouped and retested the voltage drop across the fuses. All fuses tested at 0.001 mV to 0.005 mV on a lab grade DVM except #9, 0.330 mV. By removing the fuse from #9 the amperage across the battery drops to 0.020 amps. Drop the fuse in and I can hear the siren try to sound but it just buzzes a bit and the sound goes away but the 0.180 Amp draw remains. For now, I just pulled the fuse, the car is garaged for the winter. Somebody posted step-by-step instructions to get to the siren and remove it. I'll do that next time we get 40+ degree Temps here in Connecticut.
Thanks to all for the input, the forum works!

Jan 5, 2025 | 01:05 PM

#24 (permalink)

pizzaguy

Administrator

Joined: Jun 2009

Posts: 13,932

Likes: 1,266

From: Fort Worth, Texas

Re: How to Diagnose a Battery Drain

Quote:

Originally Posted by Capt_TJM

By removing the fuse from #9 the amperage across the battery drops to 0.020 amps. Drop the fuse in and I can hear the siren try to sound but it just buzzes a bit and the sound goes away but the 0.180 Amp draw remains.

You have proved what the issue is right there. Our spec is "less than .058 amp" but most base/SE models seem to run .015 to .020, mine varies from .016 to .019; my limiteds ran .040-.055.

At .020 or less, you can go 3-6 weeks without starting the car. I start mine every three weeks anyway. I do not use battery tenders or chargers.

Jan 6, 2025 | 01:35 AM

#25 (permalink)

M60A3Driver

Senior Member

Joined: May 2023

Posts: 2,973

Likes: 1,564

From: New Jersey

Re: How to Diagnose a Battery Drain

Quote:

Originally Posted by Capt_TJM

Hi,
You may be referring to a post I did on replacing the siren and cleaning the drains. The post is in 2 parts. You can bookmark them for future use if you find them helpful.
Here are the links:
LINK Alarm siren replacement & drain cleaning PART 1

LINK Alarm siren replacement $ drain cleaning PART 2