What is the normal circuit (battery) drain when locked?

[Assimilator1]

Wondering if anyone knows here what the normal circuit drain is for these? As in car locked, and after 5 minutes, or whenever it is the alarm fully goes to sleep/standby.

My M3's been garaged since December* , the newTIS site (before it got shut down ), stated that the battery should last 4 weeks (connected). Well my old battery wasn't even lasting 2 weeks, it was the original battery so I made (a possibly bad) assumption it was just shot.

I replaced the battery in August and reset the battery counter, whilst it does hold out better it's still significantly discharging, e.g in the past 2 1/2 weeks it's gone from 12.86v to 12.18v.
I checked the circuit drain (car locked, and observed for ~11 mins), after ~5mins it dropped from a few amps or so down to 0.72A and didn't drop lower than that, which seems rather high to me.
I recall an auto electrician (who we occasionally use at work, and I've known him for some years from a prior garage, I'm going to see if I can find his number) say that BMW's often draw about 0.5A after quite a long time for powering down, but I don't remember how long is needed. So going by him, it is an excessive drain, but have I waited long enough?

To check drain btw, I put my DMM inline of the battery and earth lead, pushed the boot latch in and locked the car with the remote (being a tech I've done the drain test a few times ).
But now that newTIS has been shut down I can't find out what the normal drain is supposed to be.

*If you're wondering why, it's because 1st I garaged it for the winter, then I decided in February that I am going to do the rod bearings and won't drive it until then. Whilst I was researching parts etc lockdown hit in March, and I was furloughed until August! Added to that slow replies from Mpower, then he had a spate of bad things happen to him and his family, and only somewhat later did I discover that deansbimmer also does the mix and measuring of shells that I was after, a further delay is that their is/was a backorder on ACL shells! Hopefully I'll get the shells next month and then I can get my car back on the road......except it'll be winter by then! Arrgghh

[DukeofAlexandria]

I don't know what the draw/normal drain is on these, but I've trouble shot E85's, E46's, and now my E93 so a couple things to consider...

- Most of the new vehicles won't see much more than a few milliamps of drain over a few weeks; maybe 50-100mA.
- Going from 12.86V to 12.18V in the span of 2 weeks isn't unheard of, but that might be the bottom of the threshold and I would expect the battery to start without issue if it's not deep discharged over months.
- Do you have any accessories installed? Chargers, Dash Cam with battery backups, GPS monitoring system, car theft system, etc. and were they installed correctly?
- Have you tested the alternator to see if it's charging the battery? Should see a spike in volts up to above 14 - usually in the ~13.9V-14.4V range.
- Have you went down the fuse box and done a draw down test on all 'hot off' vs 'hot on ignition' fuses to see if you have a parasitic drain?
- How cold is it there or have you had a huge cold snap in the last 2 weeks? Might expect to see that delta if it got REALLY cold in a short time due to increased resistance.

Start with these and get back to us, thanks!

-Duke

[Assimilator1]

50-100mA? Hmm, I'd have to disagree there, I wouldn't have thought their would be many modern cars that go below 200mA, but then theirs so much variation! . A friend of mine I spoke to today (who was an AA recovery guy and who also was a real mechanic) reckoned about 400mA for BMs is normal, either way mine's well over that! Oh and he reckoned it could take as long as 20mins to fully power down, which rings a bell with the electrician's figure I wasn't sure of (didn't get to ring him today).

2.It probably would have started (I didn't try, I just took it off to charge it), it certainly started before at a slightly lower charge. But I think at that charge level it wouldn't have lasted another 2 weeks.
3.None of those except the factory GPS and alarm.
4.Yep in that range. Last time I had it running the charging all checked out ok (even when it was charging a depleted battery).
5.Not sure on your terminology there, but I haven't pulled fuses yet to see which circuit is responsible for the high idle drain (assuming I don't just need to wait longer). I'm furloughed atm and can't get to my toolbox as work is closed (going back the 30th), but that will be my next step if the drain remains beyond 20mins.
6.I reckon the temps have been from about 5-15C, mostly 10-15C, it's been really quite mild so far. (I'm in the UK JFYI).

Thanks for your reply , I don't suppose you want to do a drain test on your M3 so we have a comparison?

Cheers
Mark

[edit] Forgot to say, if it turns out the drain remains beyond 20 mins, the 1st circuit I will isolate (if I can) is the mirror heaters. Both mirror heaters are dead, and I narrowed it down to the control modules in the mirrors themselves being faulty (my car has memory seats, which means the mirror electrics are different), the mirror motors work fine, just the heating circuits are dead. I would have thought the units would be completely switched off when the ignition is off anyway, but I'm beginning to wonder now.......

[BPMSport]

Does your start button stay illuminated 10 minutes after locking the car?

[Assimilator1]

Good question, I don't know offhand, I'll have to check.
What are you thinking?

[ES BMW]

Usually a start button still lit 10-15 minutes after you lock your car points to a component that isn't going to sleep like it should. Had that happen to me until I replaced the EDC module. There were also codes thrown that pointed to it malfunctioning.

[Assimilator1]

EDC = Electronic Damper Control right?
In which case, my car doesn't have that

Last time I hooked up the snap-on diag machine (and took a photo), the only codes were relating to the mirror heaters, and coolant and intake air temp sensors. The latter 2 cleared and hadn't returned a few days or so later (I will check for those 2 again before, or just after it goes back on the road again).

[Assimilator1]

I got this PM from MilehighM3 which sheds some more light on it (he ok'd me posting it btw).

Originally Posted by MilehighM3

I read your thread and would like to comment, .

I've been a BMW master tech for a bit over 20 years and still currently service daily, if that qualifies anything below.

One thing to remember on the draw test is not to interrupt the power supply when connecting your meter.

The max draw on the car is mostly achieved at the 16 minute mark, whether the car is locked or unlocked. It occasionally wakes up to check assist connectivity/messages like it did when the car was under warranty, but those spikes are very brief and up to around 100-400mA. The max draw while the car is asleep is ~30-50mA or .030-.050A. The car powers down everything and will achieve that power level. That being said, if the car spikes above above 100mA, you should see a check control message saying increased battery drain/discharge.

If you have a functional version of ISTA, it will tell you what the draw has been in the last 32 drive cycles and if you're lucky, what's causing the draw.

Some common things are door handles if you have comfort access, RDC control modules on roughly 10 and newer cars, accessories wired in etc.

I hope this helps. Keep the thread updated with your findings.

Cheers
Bryan

So it seems interrupting the power prior to a drain test can cause problems, (I haven't found out what yet), which makes it trickier to do (this weekend) seeing as I can't access my tools until Monday.
And the current draw is indeed quite low after 16 minutes.

[bvrider1]

Some good info in this thread. Subscribing...

[Assimilator1]

So I re-tested the circuit drain last weekend, although I again disconnected the battery (I didn't have time to disconnect the earth lead from the body, which although it is bolted inside the car, it's behind a trim panel, and I had to go out!). Anyway, the drain did indeed drop off at about 16 mins, it went from ~0.7A to ~0.5A, so lower but still excessive it seems.
Oh and the start button was not illuminated at the end of that (I didn't see when it went off though).

I'll do the test again this weekend, this time disconnecting the earth from the body after I've connected up my DMM.

[C-los]

The reason for not interrupting the power supply (i.e. disconnect the battery to install an amp meter) is sometimes a module may hard reset (forced off), and will not cause the parasitic drain you are looking for until you turn it all back on, drive and park again to allow the car to attempt to go back to sleep

[Assimilator1]

Good to know, thanks .

So I can't drive it atm, but I did have to take it out the garage and charge the battery today, so I left it running for 1/2 hr.
After that I opened the boot, pushed the latched in and locked the car. I hooked up my DMM to the negative terminal and a body earth point, then disconnected the main earth and waited ~20 mins.
It went from 0.7A to 0.47A (after ~16mins) but no lower, so I do have any excessive drain, damn!
Next I'm going to have to isolate circuits.

I'm going to start with the mirrors (if I can) as the heaters don't work due to faulty modules, then try other circuits.
Bearing in mind my M3 doesn't have EDC, does anyone know any other common causes of excessive battery drain?

[Helmsman]

Haven't read about anything other than the EDC module. Half amp is pretty substancial, no codes? What about starting to pull fuses?

[Assimilator1]

Codes as per my post on 26/11, possibly it's down to the faulty mirror modules, but I would have thought they'd have their power cut off by the BCM (IIRC) when the ignition is switched off.
Not got around to pulling fuses yet, that'll be the next stage, when I have time and if it isn't raining. Tempted to leave the whole thing until I bring the car into the workshop for the rod bearings, but that's likely still several weeks away and in the meantime I have to keep charging the battery every 2 weeks which is a PITA!
If I could isolate the responsible circuit though at least I wouldn't have to do that!

[Helmsman]

Originally Posted by Assimilator1

Codes as per my post on 26/11, possibly it's down to the faulty mirror modules, but I would have thought they'd have their power cut off by the BCM (IIRC) when the ignition is switched off.
Not got around to pulling fuses yet, that'll be the next stage, when I have time and if it isn't raining. Tempted to leave the whole thing until I bring the car into the workshop for the rod bearings, but that's likely still several weeks away and in the meantime I have to keep charging the battery every 2 weeks which is a PITA!
If I could isolate the responsible circuit though at least I wouldn't have to do that!

Hmm.. at least its possible to power up the mirrows after ignition is off (getting them in by holding down remote lock, assuming coded that way). I'd continue the mirror chase mate!

Ps. Also, pulling fuses surely can't be a massive project, even believe you have the chart hidden in the box - do it!

[Assimilator1]

Do you know how many fuses these cars have (and many modern cars)??

Mine aren't self folding mirrors, if that makes any difference?
I'll still try the mirror fuses 1st anyway. Will see if I can do it this weekend, weather allowing!

PS Just ordered bearings and bolts from deansbimmer! Hmm, I need to sort out the other bits.....

[Helmsman]

Originally Posted by Assimilator1

Do you know how many fuses these cars have (and many modern cars)??

Mine aren't self folding mirrors, if that makes any difference?
I'll still try the mirror fuses 1st anyway. Will see if I can do it this weekend, weather allowing!

PS Just ordered bearings and bolts from deansbimmer! Hmm, I need to sort out the other bits.....

Mine where'nt self folding either before I coded them (Carly), but have a buttom for manual folding. Maybe that isn't standard? If not, I wouldn't be surpriced if all are using the same mirror with built in servo.

It is a lot of fuses mate, will keep you busy for a weekend..!

[BP709]

When the vehicle is totally in "sleep" mode you should have less than 50-80ma. It's been that way since the E65 came out and everything since then has on board "energy diagnosis"Above that it will trigger an increased battery discharge warning. Most modern BMW's will be far less than that. I just worked on a F02 750i that had a large draw of 4.5amps due to a auxiliary water pump leaking coolant through its connector and shorting out. Once disconnected the draw dropped to below 20ma. Few months ago had a brand new 2020 M8 Competition that an aftermarket shop wired in a k40 to the main battery cable causing a 1.5amp draw. Disconnected it was also below 20ma.

[Matthew III]

sorry to ask but does the drainage get affected more so if the car is unlocked vs locked? I leave my car unlocked in the garage and drive it about every 2 weeks. should I be locking the car to reduce the battery drainage?

[BP709]

Originally Posted by Matthew III

sorry to ask but does the drainage get affected more so if the car is unlocked vs locked? I leave my car unlocked in the garage and drive it about every 2 weeks. should I be locking the car to reduce the battery drainage?

Originally Posted by Matthew III

sorry to ask but does the drainage get affected more so if the car is unlocked vs locked? I leave my car unlocked in the garage and drive it about every 2 weeks. should I be locking the car to reduce the battery drainage?

Doesn't matter. Usually between 30 min to an hour depending on the car it should be in "sleep" mode.

[jvictormp]

Have you ever thought it's normal that the battery voltage drops to 12V after a little time?

When engine's on, voltage should be at least 13.5V. After you turn off the engine, that voltage decreases fast and gradually slowing until it stops in 12V.

EDIT: Sorry, rest voltage actually is 12.6V

[exVtekGuy]

Originally Posted by Matthew III

sorry to ask but does the drainage get affected more so if the car is unlocked vs locked? I leave my car unlocked in the garage and drive it about every 2 weeks. should I be locking the car to reduce the battery drainage?

i don't know about sleep mode but i always lock my car. This will ensure that everything possible is off and also would catch any door or trunk that might be slightly open accidentally. i drive sporadically and charger up with trickle charger once every other month and this seems to keep the battery working ok.