0.75A Battery Drain - Fuse 33 (10A) Cigarette Lighter

[persiandude]

I decided to wire a dual USB charger into by car while I have my interior taken off.

I have been getting a 5.2mV (~0.75A) drain on Fuse 33 (10A Cigarette Lighter) which drains the battery over the course of a few days.

- Wired the power of the charger to the Violet/White radio wire
- Wired the ground of the charger to the cigarette lighter ground
- The charger works when the car is on - blue light on the charger
- The charger doesn’t work when the car is off
- I have a new battery

Is this a normal draw with an accessory added?

F3901225-37BC-4DC1-A06A-5B7C017FFF60.jpg
3B7D33ED-3FAB-4CF7-9C22-8BE479ED75C0.jpg

[NeilM]

That's a function of the accessory you added. Most USB chargers always draw some power, and yours draws more than most.

Rewire it to a switched source.

Neil

[adamnur]

I used the glovebox flashlight power as it's switched with ignition, should be plenty for your usb charger.

[persiandude]

great thanks! I will rewire it and test

[persiandude]

I connected to the flashlight in the glovebox and still have a draw - the double usb socket that I’ve wired into it has an inline fuse. Could that be the source of the power drain?

Double USB is basic, 5v 1A and 5v 2.1A

[Ateyourv8]

You actually have more than just the cigarette lighter on that fuse. Heres a diagram of everything that fuse is for. Hope it helps!
lighter.JPG

[persiandude]

I started with the trunk light and opened the trunk after a few minutes of being closed with the battery connected. The bulb was so hot, so I disconnected the bulb and test the mV reading at the fuse.

With the bulb in: 5.1mV
With the bulb out: 11.91V (not mV) —- not sure why it would be so high. Any thoughts?

I’m using this method
https://youtu.be/lRcj1fQcWwU

[AJLM34A]

Red/white wires are B+. The wire diagram in post #6 shows the charge socket is red/white.

Violet/white wires are switched ignition.

Since your interior out, you can easily use the phone power connector that is located around the parking brake/armrest base. It can be pulled back in front of the shifter.

[persiandude]

Left the battery connected overnight to see if the trunk bulb was the cause of the battery drain. Battery was nearly dead - no start but dash lights would still come on.

[M52 POWER!]

I don't care what that video says you need to be looking at mA of your battery in series with your DMM. Pull fuses/disconnect things in the car until the idle current plummets. You should be at 15mA on an E36, not 750mA.

[shogun]

E36 has 30mA, not 15
Maximum closed current by vehicle: E31 50mA, E32 50mA, E34 40mA, E36 30mA, E38 50mA, E39 40mA, E46 40mA, E52 50mA, E53 40mA, Z3 30mA

Performing Closed Current Draw Test
• Select proper measuring device (DISplus, MoDic or DVOM)
-Remember amperage draw in excess of 10A will damage DVOM.
-Use inductive amp probe of DISplus when amperage draw is high.
-When using DISplus inductive probe, clamp on negative battery cable with arrow pointing away from battery. Switch off all consumers. (It is not necessary to disconnect B- from body when using inductive probe)
• Connect (-) test lead to negative battery terminal and (+) test lead to a known good ground.
• Ensure all systems are OFF !
• Be sure DVOM is on and set in proper mode.
• Disconnect battery ground lead from body.
• Observe meter reading, wait 16 minutes for vehicle to enter sleep mode.
• Identify faulty circuit by disconnecting fuses, relays, control modules or connectors, observing meter readings.
• Defective circuit is found when current is below maximum closed current for vehicle being tested.

use this link for more details http://www.e38.org/battery.pdf

[persiandude]

I don't care what that video says you need to be looking at mA of your battery in series with your DMM. Pull fuses/disconnect things in the car until the idle current plummets. You should be at 15mA on an E36, not 750mA.

Thanks gonna work on that Thursday

E36 has 30mA, not 15
Maximum closed current by vehicle: E31 50mA, E32 50mA, E34 40mA, E36 30mA, E38 50mA, E39 40mA, E46 40mA, E52 50mA, E53 40mA, Z3 30mA

Performing Closed Current Draw Test
• Select proper measuring device (DISplus, MoDic or DVOM)
-Remember amperage draw in excess of 10A will damage DVOM.
-Use inductive amp probe of DISplus when amperage draw is high.
-When using DISplus inductive probe, clamp on negative battery cable with arrow pointing away from battery. Switch off all consumers. (It is not necessary to disconnect B- from body when using inductive probe)
• Connect (-) test lead to negative battery terminal and (+) test lead to a known good ground.
• Ensure all systems are OFF !
• Be sure DVOM is on and set in proper mode.
• Disconnect battery ground lead from body.
• Observe meter reading, wait 16 minutes for vehicle to enter sleep mode.
• Identify faulty circuit by disconnecting fuses, relays, control modules or connectors, observing meter readings.
• Defective circuit is found when current is below maximum closed current for vehicle being tested.

use this link for more details http://www.e38.org/battery.pdf

Great info - much appreciated

[M52 POWER!]

E36 has 30mA, not 15
Maximum closed current by vehicle: E31 50mA, E32 50mA, E34 40mA, E36 30mA, E38 50mA, E39 40mA, E46 40mA, E52 50mA, E53 40mA, Z3 30mA

You're quoting the maximum, my number was typical, usual, expected. In fact I literally last week measured it on my car as I was doing some wiring and saved the picture....

[M3C]

Subscribed.

[persiandude]

Here is my set up to test the draw. However the reading is zero, none of the lights are on when it’s set like this etc... I reconnected the negative terminal and I took a video inside the trunk after closing it - the trunk light remained on with the trunk lid closed. 2 questions:

1. Is my setup incorrect for testing amp draw?
2. Is there a DIY for the trunk light switch? I searched but couldn’t really find one.
36459621-5E6D-4151-A905-1BBA2FBE7588.jpg

[AlpineM345]

Here is my set up to test the draw. However the reading is zero, none of the lights are on when it’s set like this etc... I reconnected the negative terminal and I took a video inside the trunk after closing it - the trunk light remained on with the trunk lid closed. 2 questions:

1. Is my setup incorrect for testing amp draw?
2. Is there a DIY for the trunk light switch? I searched but couldn’t really find one.
36459621-5E6D-4151-A905-1BBA2FBE7588.jpg

Your wiring looks fine for measuring the amp draw. It's hard to see but it looks like your red connector on the meter needs to be plugged in the right side. mA is on the right side and A is on the left side.

[M52 POWER!]

On your DMM you have it set to AC amps (the ~ line gives it away), which will show 0A on a DC circuit. Not familiar with that meter, but you likely need to press the function button to change it to DC amps.

AC left, DC right.
amps.JPG

Edit: one more thing, make sure you don't pull any loads that are > 10A or it'll immediately pop the fuse in the meter. Loads like door locks, windows, headlights, AC fan etc need to be avoided.

[marvinstockman]

M52, I never question a man who uses a Fluke!