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12v battery issues with aftermarket subwoofer amp. Not covered under warranty PSA.

MrChoi

Member
Apr 29, 2019
61
13
California
Anyone with an aftermarket subwoofer and amp have any issues with their 12v battery? I got a warning message about the 12v battery and that service is required. I took it to the service center and later told me that the battery is not covered under warranty due to the aftermarket subwoofer. They first told me that the battery was being over charged (bullshit meter activated) and then added that the vehicle is detecting excessive energy draw. Excessive energy draw makes sense since an external source is taking away energy but what doesn't make sense is the failure of the 12v battery when the DC to DC converter should be supplying constant power just like an alternator in an ICE car.

Anyways, anyone have an issue with this? Also, don't add any aftermarket anything unless you want your warranty to expire.
 
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Reactions: C141medic

MrChoi

Member
Apr 29, 2019
61
13
California
Oh, I just remembered. Don't directly tap your 12v power/energy under the seat where the DC to DC converter is located. It caused an error and disable my vehicle. I removed the amp while waiting for the tow and it was towed to the service center where it started up without a problem. They replaced the "drive left control module" but the problem came right back once I reconnected the amp. So knowing that, I went straight to the 12v battery in the front and didn't have a problem until last week.

Curious to see if there is a fix around this.
 

SomeJoe7777

Marginally-Known Member
Mar 28, 2015
2,174
5,601
Houston, TX
=They first told me that the battery was being over charged (bullshit meter activated) and then added that the vehicle is detecting excessive energy draw. Excessive energy draw makes sense since an external source is taking away energy but what doesn't make sense is the failure of the 12v battery when the DC to DC converter should be supplying constant power just like an alternator in an ICE car.

This explanation is correct.

The Model 3 has a power controller that carefully audits the total energy drawn out of the 12V battery by accessories, and total energy that is put into the 12V battery by the DC-DC converter. If, over time, those total energy values begin to diverge and do not match each other, the system thinks something is wrong with the 12V battery.

The issue is that you have hooked the amplifier to the battery directly, so the energy that goes out of the 12V battery to the amplifier is not audited. This causes the power controller to think that the total energy that has come out of your 12V battery is a lot less than what's being put in, which is a sign that the 12V battery is bad (won't take a charge).

You must connect the amplifier to a 12V source in the car that is on the audited side of the power controller, not directly to the 12V battery.

Aftermarket dashcams that record while parked have this same problem. The recommended solution is to use a backup battery to power the dashcam which can charge off an audited source rather than hook the dashcam directly to the 12V battery. BlackVue makes an accessory called the PowerMagic Ultra Battery specifically for this purpose.
 

MP3Mike

Well-Known Member
Feb 1, 2016
15,324
33,239
Oregon
Excessive energy draw makes sense since an external source is taking away energy but what doesn't make sense is the failure of the 12v battery when the DC to DC converter should be supplying constant power just like an alternator in an ICE car.

Sure when driving, but the DC-DC converter isn't on all the time. My guess is that your amp has a significant enough vampire drain to run the battery down, which triggers the DC-DC to turn on and charge it, too often. You can cycle these small batteries fairly quickly and wear them out.
 

smagicmans

Member
Mar 26, 2019
51
60
california
Oh, I just remembered. Don't directly tap your 12v power/energy under the seat where the DC to DC converter is located. It caused an error and disable my vehicle. I removed the amp while waiting for the tow and it was towed to the service center where it started up without a problem. They replaced the "drive left control module" but the problem came right back once I reconnected the amp. So knowing that, I went straight to the 12v battery in the front and didn't have a problem until last week.

Curious to see if there is a fix around this.
I think adding a relay to the sub amp and using DC to DC power will fix error.This is mentioned in this thread or this one.
 

MrChoi

Member
Apr 29, 2019
61
13
California
This explanation is correct.

The Model 3 has a power controller that carefully audits the total energy drawn out of the 12V battery by accessories, and total energy that is put into the 12V battery by the DC-DC converter. If, over time, those total energy values begin to diverge and do not match each other, the system thinks something is wrong with the 12V battery.

The issue is that you have hooked the amplifier to the battery directly, so the energy that goes out of the 12V battery to the amplifier is not audited. This causes the power controller to think that the total energy that has come out of your 12V battery is a lot less than what's being put in, which is a sign that the 12V battery is bad (won't take a charge).

You must connect the amplifier to a 12V source in the car that is on the audited side of the power controller, not directly to the 12V battery.

Aftermarket dashcams that record while parked have this same problem. The recommended solution is to use a backup battery to power the dashcam which can charge off an audited source rather than hook the dashcam directly to the 12V battery. BlackVue makes an accessory called the PowerMagic Ultra Battery specifically for this purpose.

Do you know where I should connect the amp?

Thanks.
 

SomeJoe7777

Marginally-Known Member
Mar 28, 2015
2,174
5,601
Houston, TX
Do you know where I should connect the amp?

Thanks.

I don't know precisely. However, your target is a 12V wire that's switched (i.e. that has power only when the car is running). Those wires are guaranteed to be on the audited side of the power controller.

My BlackVue dashcam has the PowerMagic Ultra battery, and the installer hooked it into a switched 12V power wire that was down in the passenger footwell, along the outboard body panel, but I do not know which particular wire was used.
 

dhrivnak

Active Member
Jan 8, 2011
4,411
3,572
NE Tennessee
I have occasionally towed my trailer with my Model 3. The Aliner trailer has a 12V refrigerator on board that takes a good 5 amps to run. I have taken two 200 mile trips with no issue. I have the 12V connected straight to the battery. So I would not think an amp would pull more than my refrigerator. Now that said I am very surprised one would want an amp as I consider the factory stereo to be AWESOME. Any more power and I would soon need hearing aids.
 

MP3Mike

Well-Known Member
Feb 1, 2016
15,324
33,239
Oregon
I have occasionally towed my trailer with my Model 3. The Aliner trailer has a 12V refrigerator on board that takes a good 5 amps to run. I have taken two 200 mile trips with no issue. I have the 12V connected straight to the battery.

Do you have the trailer connected and the refrigerator running while you are parked and the car is turned off?
 

smatthew

Active Member
Jun 9, 2018
1,233
2,039
CA Bay Area
Sure when driving, but the DC-DC converter isn't on all the time. My guess is that your amp has a significant enough vampire drain to run the battery down, which triggers the DC-DC to turn on and charge it, too often. You can cycle these small batteries fairly quickly and wear them out.
If the car is awake and the high voltage contactors have engaged, the PCS (DC-DC converter) is active. The battery is only 33Ah. Meaning, you're lucky if you can pull 200watt-hours out of it without damaging it. Tesla ever mentions in their theory of operations that a 500ma drain (6 watts) will drain the battery rapidly. "While 500 mA is the minimum threshold to sleep, it is high enough to drain the 12 V battery to the point where it requires support relatively quickly"
 
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