Will open tailgate flatten my new battery?

[hiker]

Hi there - my 2015 D4 was in the shed for 3 days / 2 nights with tailgate upper & lower open prepping for drawers etc. New Delkor battery installed Jan21 by (reputable) auto elec - all good.

When I started the car to move it the dreaded "LOW BATTERY - START ENGINE" came up. Car started OK

Looking for input, please

Can the Body Control Module be 'tricked' into thinking the tailgate is closed? ( I have a GAP IID)

and / or should I just plug in a trickle charger to keep the battery topped up?

many thanks in advance!

cheers

[drivesafe]

Hi hiker, regardless of what caused the battery drain, put your charger on and get the battery back to a decent charged state.

Prior to working in your shed, how much doing have you done over the last few months?

[Macadamia]

most of the ECUs only properly go to sleep when the car is locked so it is well known the car uses more electricity when unlocked. Not sure if 3 days is enough to draw down the battery enough for a warning but would definitely be a contributing factor. If you'd be working in the car for a while, opening and closing doors, lights turning on, throw in a few short drives or just starting and stopping the car to move it - that seems pretty standard.

If I'm working on my car for a while I'll plug in an external battery charger. Grab yourself a bluetooth battery monitor and a charger to keep an eye on it.

[hiker]

Hi hiker, regardless of what caused the battery drain, put your charger on and get the battery back to a decent charged state.

Prior to working in your shed, how much doing have you done over the last few months?

Thanks for responding - car has done local trips, within 100kms

Interesting, though, after a 2 hour scenic drive yesterday, there are no wanings this morning.

have purchased a CTEK MXS10 just now to trickle charge etc.

[hiker]

most of the ECUs only properly go to sleep when the car is locked so it is well known the car uses more electricity when unlocked. Not sure if 3 days is enough to draw down the battery enough for a warning but would definitely be a contributing factor. If you'd be working in the car for a while, opening and closing doors, lights turning on, throw in a few short drives or just starting and stopping the car to move it - that seems pretty standard.

If I'm working on my car for a while I'll plug in an external battery charger. Grab yourself a bluetooth battery monitor and a charger to keep an eye on it.

Thanks! have just purchased a new CTEK MXS10 and bluetooth reader.

Cheers!

[josh.huber]

Did you open doors while doing it.. The bloody doors on these things wake up the car. 30amps mine pulls when you open a door. The charger is a good choice. With all the rain in NSW at the moment. I'm plugged in every 5 days for maintenance.. I've got a panel on the roof and a fridge in the back. My charger has Anderson plug on it so I can plug in mid week easily to maintenance charge.

More importantly where is the drawer photos

[Eric SDV6SE]

most of the ECUs only properly go to sleep when the car is locked so it is well known the car uses more electricity when unlocked. Not sure if 3 days is enough to draw down the battery enough for a warning but would definitely be a contributing factor. If you'd be working in the car for a while, opening and closing doors, lights turning on, throw in a few short drives or just starting and stopping the car to move it - that seems pretty standard.

If I'm working on my car for a while I'll plug in an external battery charger. Grab yourself a bluetooth battery monitor and a charger to keep an eye on it.

Imho 3 days (maybe even 1) is enough to drain / drop enough voltage to bring up that code.

Ive changed all interior lights to led, (save the one bulb in the drivers door puddle lamp, as otherwise the BCM has a hissy fit) to reduce parasitic current draw a bit, but waking up the ECUs is defintely a big draw on the system. I connect a charger if its a job over a day or so to keep the battery topped up.

[DiscoJeffster]

Imho 3 days (maybe even 1) is enough to drain / drop enough voltage to bring up that code.

Ive changed all interior lights to led, (save the one bulb in the drivers door puddle lamp, as otherwise the BCM has a hissy fit) to reduce parasitic current draw a bit, but waking up the ECUs is defintely a big draw on the system. I connect a charger if its a job over a day or so to keep the battery topped up.

I just ignore the silly BCM error for the door lights. Doesn’t hurt anything. It’s much like my never ending error about “lost communication with the EPB module” yet everything works fine

[Macadamia]

Imho 3 days (maybe even 1) is enough to drain / drop enough voltage to bring up that code.

Ive changed all interior lights to led, (save the one bulb in the drivers door puddle lamp, as otherwise the BCM has a hissy fit) to reduce parasitic current draw a bit, but waking up the ECUs is defintely a big draw on the system. I connect a charger if its a job over a day or so to keep the battery topped up.

??? I've changed all my interior lights to LED, including all the puddle lights, the glove box light, footwells, etc and I don't get any BCM error?

[drivesafe]

Hi again Hiker, you may want to carry out this battery maintenance procedure, to get your cranking battery back to a good health state.

https://www.aulro.com/afvb/the-verandah/246755-line-auto-electrical-info-8.html

[101RRS]

I might have this wrong but I understood that opening a door or the tailgate will wake the car up but when it goes back to sleep it will not wake up again if there is a door or tailgate open. Hence - if working on a car for an extended period or camping, rather than opening and closing doors all the time - leave a door open/ajar and the car will not wake up.

Hence if the tailgate was open the battery should not drain down unless something like an internal light or something else is left on.

Garry

[Eric SDV6SE]

??? I've changed all my interior lights to LED, including all the puddle lights, the glove box light, footwells, etc and I don't get any BCM error?

Hmm, i did the same, then had the issue that the drivers door puddle light would not come on. Globe cross checked all ok. Check DTC's and the BCM indicated open circuit wrror (i.w blown globe). Tried anorher led, same issue. Put filament globe back in, no issues.

[josh.huber]

I might have this wrong but I understood that opening a door or the tailgate will wake the car up but when it goes back to sleep it will not wake up again if there is a door or tailgate open. Hence - if working on a car for an extended period or camping, rather than opening and closing doors all the time - leave a door open/ajar and the car will not wake up.

Hence if the tailgate was open the battery should not drain down unless something like an internal light or something else is left on.

Garry

I checked once. And from memory opening another door woke it up. I always have the doors open that I need. With the panel I don't stress too much these days. Not that I use it enough either

[hiker]

Over the course of 3 days, the rear top and bottom were open continuously, with occasional opening of drivers door (didn't keep track).

I'm interested in the theory that having the back open will wake the system, but turn off after a short interval. Do not have any active interior lights, headlamps set to 'O' - no radio etc

In the past with several LRs and RRs I naturally thought that once the Info-screen turns off, dash off etc, then the car was effectively in sleep mode - and of course, when a door (any door) is opened, the dash etc comes to life, there's several comforting clicks and the car is awake.

The idea that the car has to be closed and locked to put it to sleep stretches my (limited) knowledge!

If we can't leave the back open then I'll be looking to purchase a solar blanket for camping trips

BTW - rear drawers are still a work in progress!

[drivesafe]

Hi again hiker, it as quite a common problem, if you open doors on you disco a few times between uses and you can end up with a flat cranking battery.

I have lost count of the number of times customers have phoned me after returning from a weekend away and have had to jump start their disco to get home.

In many cases, they were able to jump start from the auxiliary battery.

This bit of info immediately points to the probable cause for the low cranking battery.

The first question I ask them is, did they have children with them, and in the vast majority of cases, ( not all ) they did.

The next question I ask is, how often did the children go to the fridge?

Now days, with the Covid Lockdowns, I also ask them how much driving did they do before going on their weekend away.

Same question for you hiker, how much driving had you done over the months before you started working on your disco?

If you have not been driving much and/or were doing lots of short drives, then your cranking battery was probable down on charge before you even started your work.

A little extra related info about locking your disco.

After a number of installs, when customers have started their disco and as they drove off, they noticed the Yellow Triangle with the exclamation symbol, was lite up.

The first time this happened to me was in my own D4 and I near had a coronary attack.

In this situation, it is just something that is brought about by a low cranking battery.

If this happens, and back to locking your disco. If this symbol lights up after you have been doing some work on your disco, just pull over, get out of the Disco, and lock your disco.

Immediately after locking your disco, have a look at your dash, and you will see the Park Brake Light will still be on.


This is a very clever action, and it indicates that your on-board computers are still going through their Shut-Down process and once they have finished the Park Brake Light will go out.

If you had had the Yellow Triangle symbol light up, after the Park Brake Light will goes out, you can then restart the motor and the symbol will no longer come on.