Got something weird going on (Page 1/2)
Tweeder MAY 27, 11:35 PM
So I've been chasing a draw for a while now. The cars dead after a couple days of not driving. I used a autel maxi tester mx101 and went through all the fuses under the dash and there was only the door pin circuit that had a draw but went away when I pressed it 8n to simulate a closed door. Next I took of the negative post and the top ground post to frame and got only .12 amps draw on a 10A setting so not much. I have a top and side post battery that's located in the right hand trunk corner, the side negative post goes to the block of the 3800sc. Then I have another ground strap going from the top negative post to the trunk wall. I have another ground from the trunk lid to the spot on the driver's firewall (where the torsion bar goes) then to the block. I think I have one more underneath from engine to cradle, cant remember. Now back to the battery, if I have a lead on the side negative post and the side post connector that goes to the block, I get .12 amps but if I put that around strap on the top post at the same time everything goes to zero. It does the same if I put the lead on the top ground strap and top post and touch the side negative. Why would my grounds cancel each other out?
Patrick MAY 28, 12:44 AM

quote
Originally posted by Tweeder:

Why would my grounds cancel each other out?



This is right up The Ogre's alley. He should be along shortly with a treatise on grounds.

theogre MAY 28, 02:30 AM
Did you See my Cave, Battery Leaches?

Year of car?
because 84-86 w/ Gen1 HL motors can kill the battery in hours to days and can make amp meters fairly useless when their the problem. Unplug motors then watch for other problems.
MX101 tester won't test things that doesn't use fuses... HL bulbs and motors are among them. Gen1 motor problems may not show for most meter because the loads are very short spikes that most meters can't read.

I read this a few times but have no clue what you are saying.
Multiple grounds can do odd things and/or you're measuring wrong and getting odd results.
Nothing should be connected to the battery - terms when testing except the meter.

Battery to frame should have some power...
0.12a higher the normal and can drain the battery but usually takes longer then a few days.
ECM and OE radio standby power is only a few ma... Like ~ 0.035a and take weeks to drain the battery normally.

Battery died multiple times from whatever can kill the battery permanently or battery have problem to start with like a dead cell.
If happens in Winter even a low battery, below 11 to 12v, can Freeze and die. Might seem to work later but Frozen battery will have problems.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Flying_Dan MAY 28, 01:30 PM
Parasitic battery drain can be tough to locate.

As stated, if you have a pre-87', check the headlight motors.

Best I've done to track down the guilty drain is connect a multi-meter set to amps between battery post and one of the cables. Must be careful not to go beyond the rated amp of the multi-meter.

You'll hopefully see a draw, from there, start unplugging fuses, relays etc. one at a time. Hopefully one of them pulled will greatly reduce or almost eliminate the draw.
Tweeder MAY 28, 04:01 PM
this is the battery with the negative off and one wire to the cable and the other to the side post. after it sits a few mins then it now shows up as .04 as seen in the other pics.


this is the amps going to zero if i add the top ground strap and leave the meter wires the same


this is the amps if i use the ground strap with the meter and the side post


this is the extra ground i spoke of that goes from the head to the old torsion bar mount and on to the deck lid. thisis from the previous owner


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86 SE Convertible 3800sc 4t65e HD(2002), Gen V, 3.3 pulley, SD headers

[This message has been edited by Tweeder (edited 05-28-2019).]

Tweeder MAY 28, 04:11 PM
also i have no stock headlights as i have the norms flip hood

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86 SE Convertible 3800sc 4t65e HD(2002), Gen V, 3.3 pulley, SD headers

Patrick MAY 28, 05:07 PM

quote
Originally posted by Tweeder:

this is the extra ground i spoke of that goes from the head to the old torsion bar mount and on to the deck lid. thisis from the previous owner



Although the factory ground wire has been replaced with something a bit more skookum, there was always a ground wire at that location. It's connected to the RF shielding molded into the decklid.
Tweeder MAY 28, 05:08 PM

quote
Originally posted by Patrick:

Although the factory ground wire has been replaced with something a bit more skookum, there was always a ground wire at that location. It's connected to the RF shielding molded into the decklid.



ok so thats all good

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86 SE Convertible 3800sc 4t65e HD(2002), Gen V, 3.3 pulley, SD headers

Tweeder MAY 28, 05:54 PM
i unhooked the main power wire that goes to the battery from both stereo amps and the amps dropped from .04 to .03. Is .03 still enough to drain the battery after a few days of not driving? just wondering why theres a .01 amp draw on stereo amps? they're off when the car turns off.

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86 SE Convertible 3800sc 4t65e HD(2002), Gen V, 3.3 pulley, SD headers

[This message has been edited by Tweeder (edited 05-28-2019).]

theogre MAY 28, 07:46 PM
Either ground connected to battery basically short out the meter and reads 0.
You have more ground paths then you think and either wire you test, other things will use any/all grounds to get at the battery.

examples
ECM have several ground paths to frame and engine.
Most Engines has a few grounds to the frame too.

Again ~ 0.03 will drain the battery but takes weeks to see 1 or 2 volts low.
But faster when battery is bad as above.
have battery tested even if it's new. New units sometime are bad.