What's new
By:
Filters

Unknown drain on battery….

Squatch

Boom motherfucker!
Joined
Aug 6, 2020
Member Number
2445
Messages
61
Loc
The Dirty South
The shitbox 2010 Charger I drive to work is randomly discharging the battery. Sometimes it’ll sit all weekend and I’ll get in it on Monday and it’ll start up just fine, and off we go.

Other times, I’ll shut it off at 7:00a and it’ll be dead when I try to start it at lunchtime at 12:00.

I’ve started pulling the negative cable when I park, but it went dead on me again this morning in 5 hours.

On a whim, I pulled the positive cable after getting back to the office, and it started fine just now as I’m getting ready to leave the office. I’ll be pulling the positive until I can prove out whether it still discharges or not.

Now, I don’t understand how it can drain with the circuit through the battery broken.

Explain:
 
What is the battery voltage when you shut down the vehicle after a good drive?

What is the voltage with the motor running?

How filthy dirty is the top of the battery?
 
The ECM can draw up to 2 amps at least on mine it did (2007 silverado classic 6.0L).

BTW it does not appear to be protected by any fuse or breaker so real difficult to actually diagnose.
 
Last edited:
Muckin_Slusher said:
What is the battery voltage when you shut down the vehicle after a good drive?

What is the voltage with the motor running?

How filthy dirty is the top of the battery?
Click to expand...
12.4 but drops immediately to the tune of .01v/second or so.

Running voltage is 14.4-14.8ish.

Battery is clean.
 
Oddball said:
An amp clamp is handy for finding this crap. Ive had success just using a test light, but its fiddle-fuckery.
Click to expand...
I have a dc amp clamp, but like PAE alluded to, there is shit that draws amperage with the key off and I don’t have a baseline to know what is “normal”.

The battery is 6 years old so I may be troubleshooting around a bad battery. I think I’m going to replace it on principle and see if it still shows the same symptoms.
 
M92PV4U said:
This could also be from leaving the battery cable loose and it not charging when you drove to work.
Click to expand...
Negative…

I’ve thrown my FLUKE 117 in the trunk next to the battery and I’ve been checking voltage, and continuity each time I open the trunk for any reason.
 
My 5500 does the same.

Seemed like sending the TIPM out fixed it, been fine since this spring, but left it parked a couple days last week and batteries were stone dead, so not sure now.
 
Squatch said:
Negative…

I’ve thrown my FLUKE 117 in the trunk next to the battery and I’ve been checking voltage, and continuity each time I open the trunk for any reason.
Click to expand...
You can remove the negative cable and put a amp meter between the negative cable and the negative battery post and that will tell you the amp draw. You may need to put your meter on milliamps, but start with amps. You then can start pulling fuses until the draw goes away.
 
The draw never went away on mine.

Very frustrating.


M92PV4U said:
You can remove the negative cable and put a amp meter between the negative cable and the negative battery post and that will tell you the amp draw. You may need to put your meter on milliamps, but start with amps. You then can start pulling fuses until the draw goes away.
Click to expand...
 
M92PV4U said:
You can remove the negative cable and put a amp meter between the negative cable and the negative battery post and that will tell you the amp draw. You may need to put your meter on milliamps, but start with amps. You then can start pulling fuses until the draw goes away.
Click to expand...
this could also be done with an incandescent test light.
 
Was there a fuse I missed ?
 
On my 07 silverado I isolated the alternator 100% and still had the draw, ended up using a remote switch.
 
Squatch said:
I have a dc amp clamp, but like PAE alluded to, there is shit that draws amperage with the key off and I don’t have a baseline to know what is “normal”.

The battery is 6 years old so I may be troubleshooting around a bad battery. I think I’m going to replace it on principle and see if it still shows the same symptoms.
Click to expand...
Everything should time out and turn off after a max 45 minutes. 50 milliamps is the standard allowed limit for parasitic drain after that point, but on late model cars I'm pretty ok with anything under 100ma.
 
SLOWPOKE693 said:
Sounds like a shorted plate in the battery.
Click to expand...
I replaced the battery and it fixed the problem.

I didn't have a baseline for amperage draw at rest, but it showed like .5ma after cutting it off and less than that after sitting overnight so I gambled on the battery being bad and the problem hasn't returned.

I still don't understand how it was so unpredictable regarding when it would go dead.
 
You must log in or register to reply here.
Top Back Refresh