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Possible parasitic draw problem diagnosis (Stereo?)

Old 11-21-2018, 12:31 PM
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Possible parasitic draw problem diagnosis (Stereo?)

Continuation from this thread here: https://www.camaroz28.com/forums/lt1...6/#post7000928


My new battery died on me after the following: Sitting for 5 days and leaving the stereo on for about 1.5-2 hours with the car off while working on it. During the 5 days I was also installing the stereo so doors were open for a while, etc. Didn't drive it until yesterday.

After a quick stop to autozone, came back, turned on the stereo at regular listening volume for about 1.5-2 hours while installing some interior stuff. Battery drained to about 10.5v and wouldn't start the car.

Battery is new and less than a month old.



I tested for parasitic draw again this morning after an overnight charge on the tender. The battery charged up to 12.45V.

I was mistaken in my parasitic draw test from yesterday... it looks like there is no parasitic draw. My multimeter for whatever reason, will read about 166milliamps of draw when you first connect the leads but then this will go away and drop down to a normal value after about 10 seconds. Which is why I thought there was a draw. I have a 2nd multimeter that does the same thing.

When you first connect the leads, shows 166 milliamps or so and then drops down to about 5-6milliamps and stays there for as long as you leave it. So no draw. I tested it by opening the door and sure enough, the amps shot up. I also removed the stereo fuse and same deal. There's nothing to test as 5-6 milliamps is really low. Kind of weird it starts at 166milliamps when you first connect it up. What is the reason for that?



With no parasitic draw I can see... there seems to be only 3 options:
1) Bad battery - doesn't seem likely, just replaced it. never had a problem until I re-wired the stereo that the previous owner installed

2) There is no issue, everything is normal. Is it normal for the battery to die after listening to the stereo for a few hours and having the car sit for about 5 days? I don't think I experienced this with any other of my cars.

2) Something in the car is draining battery more than it should only when in use, faster than the alternator can charge back up, I.E. stereo -


Stereo Situation:
So..
any stereo or electrical experts here?
This is how the previous owner wired up the stereo.. The stock car had a bose system. He removed all the speakers except for the Bose rear speaker/amp combo in the trunk on the driver's side. Then he put in all 4 new speakers (2 front/2 sail panels) and new Sony headunit.

The way he wired it up is for the 2 front speakers... he cut the stock harness and wired the signal wires (green/white) to the speaker. The orange/black wires which are the power wires that the stock bose speakers used to have, are left untouched. So that part sounds OK.

But the rear speakers.... given that there is no harness back there he wired directly from the speaker to the headunit. The rear left speaker wires are T-spliced into front left signal wires at the stereo harness. (Same for the right side)

So you basically have the rear speakers piggybacking off the front audio+/- signal wires.

This was very strange because the balance/fader was all messed up and the Bose Rear Trunk Speaker/Sub/Amp combo was way louder than the aftermarket speakers.


So I kind of cleaned it up and T-spliced all 4 speakers into their RESPECTIVE signal wires at the stereo harness. This allows all 4 speakers to get the right signal. By T-splicing it, it also maintains the Rear Bose Trunk speaker/amp unit to continue to get audio signal because according to the wiring diagram, it looks like that rear amp gets it's signal from the stock harness rear audio+/- wires.

Now, if I were to CUT the front left &right, rear left&right wires at the harness and wire them to the speakers... that would completely bypass the Bose Trunk Unit Amp/speaker combo. I didn't do this because that unit sounds pretty good.

Unfortunately, I'm not sure if this hybrid type of audio system is causing a drain problem. The rear bose amp is tied in with the 4 aftermarket speakers and Sony headunit.
I'm curious if wiring the stereo up like this is able to cause some sort of additional power draw. Maybe not parasitic but possibly more amps to be drawn when in use?



Unfortunately I don't have an amp meter to test the actual amperage being drawn so I'm only able to do a quick and dirty stress test with volts...


With the battery fully charged, I hooked up the multimeter to volts and monitored the car for about 30 mins while running various components on the car.

9:45am - started up cold, no stereo faceplate attached. Measured 14.4V
Car continually running below:
9:50am - volts dropping slightly down to 14.16V
Headlights turned on - 13.85V
Headlights turned off - 14.10V
Turn stereo on - 14V
Stereo & Headlights together - 13.7-13.8V
Stereo & Headlights together (10 mins later) - 13.6V-13.7V
AC turned on to High - 13.2V-13.25V
AC turned off - 13.45V
AC back on - 13.2V
Headlights off - 13.76V
Stereo off - 13.75V
10:20am - Turn car and everything off - 12.35V

Leave everything off, monitor battery
10:45am - 12.75V


It doesn't seem like I have an issue from these numbers as long as the battery is charged and the car is running. But I'm not confident to go to a parking lot somewhere and listen to the radio for an hour or so while waiting on something as I do this sometimes.

I'm going to continue to monitor the battery volts over the next day or two.

The 2 questions I would answered is if this type of drain sounds normal, and if the stereo is wired in a way that might cause problem as I'm not a stereo expert.

Last edited by ridiqls; 11-21-2018 at 12:56 PM.
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Old 11-21-2018, 04:34 PM
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Re: Possible parasitic draw problem diagnosis (Stereo?)

The audio signal wires from the Bose head unit are very light gage. Installing a new amplified head unit, and trying to drive the speakers through skimpy wire isn’t going to give good results. That could explain why the rear Bose unit, spliced in closer to the head unit is louder. Of course, if I understand how the rear Bose unit is connected, you are feeding an amplified signal from the head unit into a rear unit that has its own amp. Surprised the Bose rear unit isn’t producing massive distortion.
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Old 11-21-2018, 04:48 PM
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Re: Possible parasitic draw problem diagnosis (Stereo?)

Yeah I thought that too but on the stock bose headunit, does it not send an amplified signal to the rear? I guess it wouldn't make sense to. I just saw that at the stock harness level, the rear left and right wires act as the audio signal for the rear bose unit. I guess if my headunit is sending an amplified signal, it would get amplified twice. But there's no distortion at all, it actually sounds really good.

But of course the other 4 speakers are much lower in volume. I had to "fix" this by adjusting the fader to the front to about -8, so it sounds normal.

Now it's not a big deal, I'm willing to disable/bypass that bose rear unit entirely if it's draining my battery. Is there a way to disable it other than to cut the stereo side harness rear L/R wires so it doesn't receive a signal?

The rear unit does make a loud clicking noise when you turn the stereo on and off though.
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Old 11-21-2018, 09:52 PM
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Re: Possible parasitic draw problem diagnosis (Stereo?)

Have you looked at the wiring diagram for the factory Bose system?

http://shbox.com/1/bose_wiring.jpg

You indicated there is negligible drain on the battery with no equipment operating. Leaving a single bulb on, like the dome light, overnight can kill a battery. Running a stereo system for hours at a time with the engine off would seem risky, given the hacked system. But are you indicating your multi-meter can’t measure anything other than milliamps?

I'll try and get Gary to take a look at this.
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Old 11-21-2018, 10:19 PM
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Re: Possible parasitic draw problem diagnosis (Stereo?)

Sorry, that's a lot to read. I tried to read it all but I would forget most of it by the end;-)

First, your alternator should put out at least 100 amps, far more than the typical stereo can consume.

Next, The current drain spikes at first when the battery is connected because the PCM and other modules boot up, does stuff, and then goes to rest. I would expect the startup drain to be more like a half amp or more though, so I would make sure you are using the meter correctly.

For reference, your battery is probably about a 50 Amp-hour type. So it would take 50 hours to drain the battery at a one amp load, two days.

Is there still a plug at the rear amp? If so. can't it just be unplugged?

I don't really think the radio setup is causing much drain. I assume you are measuring the current at the battery terminal using the DC setting.

Coincidentally, I recently installed a dash cam and set it to record 24/7 instead of only when the ignition is on. Ran the battery dead after I didn't drive it for 4 days. Now I keep a trickle charger on it.

Last edited by GaryDoug; 11-21-2018 at 10:25 PM.
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Old 11-21-2018, 10:25 PM
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Re: Possible parasitic draw problem diagnosis (Stereo?)

Originally Posted by GaryDoug View Post
Sorry, that's a lot to read. I tried to read it all but I would forget most of it by the end;-)

First, your alternator should put out at least 100 amps, far more than the typical stereo can consume.

Next, The current drain spikes at first when the battery is connected because the PCM and other modules boot up, does stuff, and then goes to rest. I would expect the startup drain to be more like a half amp or more though, so I would make sure you are using the meter correctly.

For reference, your battery is probably about a 50 Amp-hour type. So it would take 50 hours to drain the battery at a one amp load, two days.

I don't really think the radio setup is causing much drain. I assume you are measuring the current at the battery terminal using the DC setting.

Coincidentally, I recently installed a dash cam and set it to record 24/7 instead of only when the ignition is on. Ran the battery dead after I didn't drive it for 4 days. Now I keep a trickle charger on it.
Yeah maybe I don't have a problem. I'm trying to think back the past few days and I don't think I used the battery THAT much but I'll have to monitor this issue. Over the past 5 days, I had the door open for maybe 5 hours total while I was working on installing some stuff, listened to the stereo for about 2 hours. Nothing running 24/7 though.


So when first connecting the leads, it shows 160-200 milliamps/.16-20 amps and it drops to 5-6 milliamps and holds steady there. That makes sense, the things booting up.

I went through each fuse (both engine bay and driver's side panel) and checked for voltage drop with my mulitmeter set to mV. Nothing.. all good.

I'm checking the battery's voltage over the next few days since I'm not going to be driving and will report back what happens with it.
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Old 11-21-2018, 10:29 PM
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Re: Possible parasitic draw problem diagnosis (Stereo?)

Originally Posted by ridiqls View Post
Nothing running 24/7 though.
My dash cam only uses about 500 ma, enough to drain it in 4-5 days.

Come back with some readings over time. We will fix this.

Last edited by GaryDoug; 11-21-2018 at 10:32 PM.
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Old 11-22-2018, 01:07 PM
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Re: Possible parasitic draw problem diagnosis (Stereo?)

Today I checked the battery voltage and it is showing 12.48V. Will monitor over the weekend but I feel like dropping from 12.7 to 12.48v over 24 hours is not normal?

There was no parasitic draw when I tested but it might be possible that a component or circuit might be cycling on/off during the 24 hour period so I just didn't see it. Unfortunately, the only way to test that is to record my multimeter (probably kill my multimeter battery) or start dividing up fuses and pulling them to eliminate certain circuits.

Once I get a baseline, I'm going to check if the battery drains with the battery cables disconnected. We'll see where it goes from there.
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Old 11-24-2018, 02:56 AM
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Re: Possible parasitic draw problem diagnosis (Stereo?)

Appologies for the late input. This was on my maincomputer that's being a little awkward atm.

These figures wee recorded of a pretty stock LT1 when my battery would last several days.
If i played the cd i'd get about 2 hours,then it wouldn't start.
The alternator would just keep up with the demand and never really charged the battery.

The previous owner had a roof mounted TV and had wired the modulator direct to a permanent supply.

Checked drain on battery @ fusable links
single - 0.0
double - 0.0
double - 8.3
double - 86.6 mA


Checked all fuses for drain Ign Off Ign ON in milliAmps
17 Radio 0.03 1.16
16 Crank 0.00 0.00
15 Windows 0.00 1.07
14 Wiper/Wash 0.01 1.13
13 IPDimmer 0.00 0.40 variable with position
12 Defog / Seats 0.00 lots
*** 11 Horn / Cig 77.3 77.4 *** REMOVED FOR NOW
10 Tail 0.00 0.00
9 Gauges 0.00 0.00
8 Courtest/Radio Lights 2.60 lots
7 Power Accy 0.00 0.00
6 Stop / Hazzard 0.00 0.00
5 PCM Ign 0.00 5000.00 Fuel Pump dropping to 200mA
4 Radio Accy 0.00 0.00
3 HVAC 0.00 5000.00
2 Turns / Backup 0.00 0.00
1 AirBag 0.00 200.00

Fuse 11 drives the internal lights & presumably ALARM fitted by Prev Owner

The two double connections now drain about 8mA & 12mA which is good.

Car runs now with Alternator putting 9 - 10 Amps back into the system...

Checked TV & audio cables-
TV was draining 70mA so i removed inline fuse
FUSE 11 now drains only 6mA so car should be ok for battery drain

HTH

Mitch
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Old 11-26-2018, 12:39 PM
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Re: Possible parasitic draw problem diagnosis (Stereo?)

Originally Posted by terminal_crazy View Post
Appologies for the late input. This was on my maincomputer that's being a little awkward atm.

These figures wee recorded of a pretty stock LT1 when my battery would last several days.
If i played the cd i'd get about 2 hours,then it wouldn't start.
The alternator would just keep up with the demand and never really charged the battery.

The previous owner had a roof mounted TV and had wired the modulator direct to a permanent supply.

Checked drain on battery @ fusable links
single - 0.0
double - 0.0
double - 8.3
double - 86.6 mA


Checked all fuses for drain Ign Off Ign ON in milliAmps
17 Radio 0.03 1.16
16 Crank 0.00 0.00
15 Windows 0.00 1.07
14 Wiper/Wash 0.01 1.13
13 IPDimmer 0.00 0.40 variable with position
12 Defog / Seats 0.00 lots
*** 11 Horn / Cig 77.3 77.4 *** REMOVED FOR NOW
10 Tail 0.00 0.00
9 Gauges 0.00 0.00
8 Courtest/Radio Lights 2.60 lots
7 Power Accy 0.00 0.00
6 Stop / Hazzard 0.00 0.00
5 PCM Ign 0.00 5000.00 Fuel Pump dropping to 200mA
4 Radio Accy 0.00 0.00
3 HVAC 0.00 5000.00
2 Turns / Backup 0.00 0.00
1 AirBag 0.00 200.00

Fuse 11 drives the internal lights & presumably ALARM fitted by Prev Owner

The two double connections now drain about 8mA & 12mA which is good.

Car runs now with Alternator putting 9 - 10 Amps back into the system...

Checked TV & audio cables-
TV was draining 70mA so i removed inline fuse
FUSE 11 now drains only 6mA so car should be ok for battery drain

HTH

Mitch
Hi Mitch, Thanks for your input. Sorry if I misunderstood but kind of went over my head there. To clarify, what did you mean by the double connection at the fusible links?

After you removed fuse 11, the problem went away? Or were you saying it was the symptom that the TV was draining 70mA so once you addressed the TV, the fuse was drawing less with the ignition on?






UPDATE:
Over the Thanksgiving weekend, I monitored my battery voltage and here are the results (not great):
Wednesday Nov 21
10.45am 12.75v
11:15am 12.71v
12:37pm 12.66v
12:40pm Started car to move it. 12.82v
12:45pm Back down to 12.68v
2:45pm 12.64v
5:00pm 12.6v
6:00pm after moving car 12.64v
7:30pm 12.55v
Thursday Nov 22
10:00am 12.48v
10:45am 12.48v
2:30pm 12:49v
7:30pm 12.38v
11:00pm 12.44v
Friday Nov 23
9:45am 12.42v
4:00pm 12.41v
12:30am 12.38v
Sat Nov 24
10:00am 12.37v
3:30pm 12.36v
10:30pm 12.34v
Sun Nov 25
9:30am 12.32v
10:30pm 12.31v
Mon Nov 26 (Today)
9:45am 12.29v



So initially the first day the drop was kind of rapid. I assume it was because I charged it up on the tender and it was just returning to its natural state. Over the next 4 days, the voltage continually almost exactly .04v/day.

This doesn't seem normal although when I went to go start the car, it started right up today after sitting for 5 days. However, if I were to use the radio I'm convinced it would've died in an hour or two.


There was no parasitic draw that I tested both at the battery ground end, and at all the fuses. I did not use the car and I tried to refrain from opening the doors or doing anything with it at all over this test period. And the battery still drained.

That really leaves me with 1 option?? There's a parasitic draw that's sporadic and not continual which means, it is showing draining .04v over the course of 24 hours. I don't know what this translate to in amps but there might be a circuit that is coming on and off over the course of the day.

Other than setting up a camera and monitoring my voltmeter over a few hours, which might kill my voltmeter battery... the other option is to start pulling fuses and monitoring the drop every day but the first 24 hours after a charge isn't very accurate in judging voltage.

Might start by pulling all the fuses in the driver's side panel and start eliminating circuits. If that doesn't change anything at least I can rule out everything on that fuse box including the stereo. If it reduces or gets rid of the draw, then I can start eliminating 1/2 of the fuses at a time until I get to the right one.


Can anyone think of a particular circuit that would be susceptible to sporadically turning on? Fuses like the ignition, fog lights, etc. I don't think turn on randomly. But maybe the stereo? There must be something turning on when I cannot see it because there's no other explanation for this draw when my car hasn't been touched or driven.

Last edited by ridiqls; 11-26-2018 at 12:53 PM.
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Old 11-26-2018, 07:53 PM
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Re: Possible parasitic draw problem diagnosis (Stereo?)

There is always a continuous draw from the “PCM BAT” fuse to maintain the volatile memory in the PCM. Ditto with the stock audio head unit, to maintain the station memory and the audio security system. I realize you no longer have the stock Bose unit, but who knows how the previous owner hacked the audio system install/wiring.

An 0.04 volt drop per day doesn’t seem excessive.... that's 25 days for a 1 volt drop.

Note that there are minor differences in the fuses between 94 an 95 models. The most significant is the relocation of the “PCM BAT” fuse from the end of dash panel (94) to the under hood box (95).
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Old 11-30-2018, 11:15 PM
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Re: Possible parasitic draw problem diagnosis (Stereo?)

So I have been monitoring the battery for a while now, car has been sitting since Thanksgiving. I pulled all the fuses on the driver's side panel to see if it makes a difference. I reduced the draw to about .02 volts a day, but after you mentioned the PCM bat, that might be the difference. I put all the fuses back EXCEPT the radio fuse and back to about .04V a day in battery voltage drop.

I guess I don't have a parasitic draw problem, but the next thing I will check is how much power the radio is when active. I might buy this https://www.harborfreight.com/30-amp...ter-67724.html

30A should do it, the radio fuse is only 15A. My multimeter only goes to 10A so for $10 a good way to test all the fuses while they are running without blowing up the multimeter.


Anyway, I think so far so good. The car did start right up when I started it up today.
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Old 12-03-2018, 04:07 PM
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Re: Possible parasitic draw problem diagnosis (Stereo?)

ridiqls, was the pink wire in the harness (system power control C1-pin 8) hooked up to the new head unit or disconnected. If connected to the power control of the new head unit, it is putting +12v on the wire and it will pick the BOSE Relay. That relay provides power to the rear amp via fuse 4 (25 amp) in the IP panel. Check fuse #4 with stereo on to verify if amp is turning on. I'm sort of guessing it is, as normally any amp that is not powered on usually does not supply good sounding (if any) output.. If fuse 4 is drawing current add that draw to fuse 17 (12 v ign to radiio) and fuse 8 (12 v batt to radio) . Remember 8 may have draw without radio on as it feeds other circuits, just look at 8 w/radio off and then on, calculate difference. Ref post #4 for link to wiring.
I myself use meters like this, they are more versatile. I have a couple of different ranges, but you need a pair of alligator clips to use them.
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