12v battery problems - again

[tchavei]

Sure, but.. I would not generally recommend this; you don't want to have a short or something so be careful. Use low amp (3A or 5A) fuses for dashcam etc, and use wires that are thick enough and well insulated (I used 20awg for the splitter and 16awg from the fuses; Blackvue dashcam wires are usually 24awg which seems rather thin..).

Anyways, on the passenger side fusebox, the top row is always on, and the bottom is on when the car is "on":

Since those slots are empty these are perfect to tap as those will not connect to any device in the car.

For a Blackvue dashcam, the top row (yellow) is for the yellow wire (always on, main power), and the bottom row (red) (on when car is on) is for the red wire (to trigger parking mode). (and black is ground of course). (and again, I don't generally recommend hardwiring a dashcam as of yet since it is unclear inhowfar that would drain the 12v battery; maybe it is ok if you can set a 48h time limit on parking mode and a 12.5V or higher voltage cutoff. I enjoy this though ).

To connect to a C-Tek or bm300 just connect the yellow (top row, always on) to the "red" connector/wire (+) since we want to see the battery power always (and the black (-) to the ground screw (see below)). (I think this is fine to hardwire as these devices use almost no electricity).

Make sure to use the top slot of the fuse-tap and leave the bottom one empty.
Also, the top of each fuse row is powered, so install the fuse tap with the wire going down, e.g.

Ah, the ground screw: you can remove the side panel on the passenger side from bottom to top with a plastic tool:

and connect the ground wire to the screw there with an M8 hex nut so you don't have to touch the screw that holds the dashboard:

Excellent reply! Already saved the pictures.

Speaking of... I'm in shock. I can see extra spare fuses in the side cover! How did Porsche offered those without charging for it as an option in the Web configurator? ?

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[Mbgt72]

I didn't take a picture of the harness, I but I made a similar setup to install the CTEK lithium 12v charger and the CTEK 12v Battery Sense bluetooth device which monitors the battery and sends reports to the ios app. I lengthened the wires so that I can access the battery tender plug while still having the frunk closed if I want.

 

[800v]

I didn't take a picture of the harness, I but I made a similar setup to install the CTEK lithium 12v charger and the CTEK 12v Battery Sense bluetooth device which monitors the battery and sends reports to the ios app. I lengthened the wires so that I can access the battery tender plug while still having the frunk closed if I want.

Very nice! I can't quite see how you attached the red wire though?

 

[Mbgt72]

Very nice! I can't quite see how you attached the red wire though?

If you mean the positive lead to the battery, it is the same way that the negative is connected (under the tension screw for the battery terminals).

The pos/neg cable shown at the battery is just to extend the harness that came with the CTEK maintainer & battery sense. I then used a knife disconnect to act as a splice & disconnect if needed.

 

[ciaranob]

Sure, but.. I would not generally recommend this; you don't want to have a short or something so be careful. Use low amp (3A or 5A) fuses for dashcam etc, and use wires that are thick enough and well insulated (I used 20awg for the splitter and 16awg from the fuses; Blackvue dashcam wires are usually 24awg which seems rather thin..).

Anyways, on the passenger side fusebox, the top row is always on, and the bottom is on when the car is "on":

Since those slots are empty these are perfect to tap as those will not connect to any device in the car.

For a Blackvue dashcam, the top row (yellow) is for the yellow wire (always on, main power), and the bottom row (red) (on when car is on) is for the red wire (to trigger parking mode). (and black is ground of course). (and again, I don't generally recommend hardwiring a dashcam as of yet since it is unclear inhowfar that would drain the 12v battery; maybe it is ok if you can set a 48h time limit on parking mode and a 12.5V or higher voltage cutoff. I enjoy this though ).

To connect to a C-Tek or bm300 just connect the yellow (top row, always on) to the "red" connector/wire (+) since we want to see the battery power always (and the black (-) to the ground screw (see below)). (I think this is fine to hardwire as these devices use almost no electricity).

Make sure to use the top slot of the fuse-tap and leave the bottom one empty.
Also, the top of each fuse row is powered, so install the fuse tap with the wire going down, e.g.

Ah, the ground screw: you can remove the side panel on the passenger side from bottom to top with a plastic tool:

and connect the ground wire to the screw there with an M8 hex nut so you don't have to touch the screw that holds the dashboard:

Excellent post - thx! I was actually only referring to my Ctek battery sense hook-up (as opposed to direct battery conection) - I have a FitCamX already installed and very happy with it so no plans to go to the fuse box for that.

BTW, in respect any direct connection to the battery for those that have disconnected the neg cable, is it always the case that you have to then reset various items in the PCM, TPMS etc or if it is done fast enough (i.e. adding the Ctek terminal connection) can the system handle that short disconnect and avoid all the resets?

 

[PDACPA]

Sure, but.. I would not generally recommend this; you don't want to have a short or something so be careful. Use low amp (3A or 5A) fuses for dashcam etc, and use wires that are thick enough and well insulated (I used 20awg for the splitter and 16awg from the fuses; Blackvue dashcam wires are usually 24awg which seems rather thin..).

Anyways, on the passenger side fusebox, the top row is always on, and the bottom is on when the car is "on":

Since those slots are empty these are perfect to tap as those will not connect to any device in the car.

For a Blackvue dashcam, the top row (yellow) is for the yellow wire (always on, main power), and the bottom row (red) (on when car is on) is for the red wire (to trigger parking mode). (and black is ground of course). (and again, I don't generally recommend hardwiring a dashcam as of yet since it is unclear inhowfar that would drain the 12v battery; maybe it is ok if you can set a 48h time limit on parking mode and a 12.5V or higher voltage cutoff. I enjoy this though ).

Just to add a comment on the dashcam. I have my Blackvue 900X 2CH hardwired as described. the 900x has the ability to monitor voltage and shuts off if the voltage drops. Limits can be set in the app (the 750 model needs a separate device). Been running mine for almost a year and half and no issues. You get a text alert from Blackvue when it disconnects and reconnects when the car is parked and locked. I speculate, the 12v gets recharged by the DC-DC using the HV battery and then the Blackvue turns back on in Parking mode.

 

[800v]

Just to add a comment on the dashcam. I have my Blackvue 900X 2CH hardwired as described. the 900x has the ability to monitor voltage and shuts off if the voltage drops. Limits can be set in the app (the 750 model needs a separate device). Been running mine for almost a year and half and no issues.

Nice -- that is good to hear. I guess that the dashcam voltage cutoff is high enough that once it triggers the 12V battery still have enough charge to last for a while. Can you check what the voltage cutoff is that you have set? Is there a maximum time set for parking mode as well?

 

[PDACPA]

Nice -- that is good to hear. I guess that the dashcam voltage cutoff is high enough that once it triggers the 12V battery still have enough charge to last for a while. Can you check what the voltage cutoff is that you have set? Is there a maximum time set for parking mode as well?

Screen shots from the app. I do not have any max time set for parking mode. Just goes into it when the car is shut off and then resumes when the car turns off. I will say I have been driving and hear it turn on and wonder why it was delayed. I think my SD card is too small or maybe heat. Have not dug into that yet.

 

[800v]

Thanks! but wow... a 12V cut off seems very low... I guess I would set it to 12.5V at least. On the other hand, I am just guessing and have not yet been able to measure exactly what the car drain is, and at what voltage exactly the recharge kicks in
Good to hear though it seems to work for you!

 

[simcity]

Thanks! but wow... a 12V cut off seems very low... I guess I would set it to 12.5V at least. On the other hand, I am just guessing and have not yet been able to measure exactly what the car drain is, and at what voltage exactly the recharge kicks in
Good to hear though it seems to work for you!

How accurate is the Bluetooth sensor? Perhaps double check it with a DMM if you can. Quite small voltage differences (less than 0.1v) on these batteries imply a large difference in the SoC especially in the flattest part of the discharge curve.

Be also interesting to know how much parasitic drain the sensor takes. I’m guessing it lies fairly much dormant but still awake enough to take readings and respond to Bluetooth wake up from the phone etc.

 

[tchavei]

The ctek sense has a 1mAh draw according to the spec sheet. That's barely anything (specially compared to a dual dashcam that will draw 300-600mAh in parking mode )

 

[PDACPA]

Thanks! but wow... a 12V cut off seems very low... I guess I would set it to 12.5V at least. On the other hand, I am just guessing and have not yet been able to measure exactly what the car drain is, and at what voltage exactly the recharge kicks in
Good to hear though it seems to work for you!

I basically left it at the factory settings which you see. I have not measured the drain, but have had zero issue with it. Every now and then it disconnects and reconnects on its own. Could be hitting a slight drop, but I am not sure.

 

[PDACPA]

How accurate is the Bluetooth sensor? Perhaps double check it with a DMM if you can. Quite small voltage differences (less than 0.1v) on these batteries imply a large difference in the SoC especially in the flattest part of the discharge curve.

Be also interesting to know how much parasitic drain the sensor takes. I’m guessing it lies fairly much dormant but still awake enough to take readings and respond to Bluetooth wake up from the phone etc.

So when it is in parking mode, I can see through my tint a tiny white dot which is the light on the camera. In the mornings you can see the circle where no morning dew is because of the light. It will pick up motion if you walk by. If it rains, the motion goes off. I dialed back the motion sensing as I was getting way too many alerts. So it is definitely on, but must be very minor drain. I do get the disconnect and then reconnect. I guess this is the 12v drop, it shuts off, the 12v gets recharged by the HV and then the camera comes back on.

 

[simcity]

So when it is in parking mode, I can see through my tint a tiny white dot which is the light on the camera. In the mornings you can see the circle where no morning dew is because of the light. It will pick up motion if you walk by. If it rains, the motion goes off. I dialed back the motion sensing as I was getting way too many alerts. So it is definitely on, but must be very minor drain. I do get the disconnect and then reconnect. I guess this is the 12v drop, it shuts off, the 12v gets recharged by the HV and then the camera comes back on.

Camera or CTEK Battery Sense thing? I was on about the latter.

 

[simcity]

Thanks! but wow... a 12V cut off seems very low... I guess I would set it to 12.5V at least. On the other hand, I am just guessing and have not yet been able to measure exactly what the car drain is, and at what voltage exactly the recharge kicks in
Good to hear though it seems to work for you!

Should kick in at 20% SoC (8 Ah remaining) according to the Audi self study guide for the e-tron GT. So that’s around 12.9 volts.

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