Parasitic drain possible alternator while sleeping?

[Straycat_67]

Hi guys,

Bit of advice if I may.

Couple of weeks ago my X5 2011 (Non comfort access) decided to have a totally flat battery. Hadn't driven it for maybe 2-3 days, never had an issue before. Pressed the fob, nothing happened, tried the spare fob, same result. Got in the car via the emergency key, put the fob in and alarm started going off. Called breakdown services and they got the jump booster on it and we're up and running again. Few nights later noticed the start/stop light on hours after i'd locked the car, presume the car decided to wake up of it's own accord!
Within 36-48 hours the cars dead! So a huge drain somewhere.

* Battery is a 2 yr old AGM and according to a garage, emergency breakdown and auto electrician is fine, alternator also working as it should when running.

Long story short... called out a mobile auto electrician, he was not able to find the drain culprit, car was going to sleep leaving 0.07-0.08 reading on his multimeter. However, while testing with car not running he burnt out two set's of multimeter cables with 14 odd volts passing through the battery (car was off)! He seems to think it might be the alternator, so has disconnected under the bonnet and asked me to keep an eye out over the next 72 hours, then see if the drain has stopped. Been 36 hours and so far so good re opening the car, didn't want to start yet as want to leave it the full 72 hours.

Could the alternator be waking up at various times when car is off causing a huge drain? Has it happened to anyone else?

Lastly, if this is the problem, any ideas what a parts and labour cost would be to replace? It's difficult at the moment due to Coronavirus with respect the options for repairs can be done. Didn't want to take it to my main dealer as they want £118 just to do a diagnostics let alone the cost of a replacement alternator.

Sorry if I've not explained properly, not a total whizz when it comes to car tech stuff!

Appreciate if anyone can give any guidance, I've tried reading across all forums but nothing other than the usual stuff, no alternators waking up and draining.

[Wayfarer]

Hi
Definitely not an expert on this but would suggest the symptoms your car has is probably related to the Alternator diode block or voltage regulator, again not sure if they are available separately or if a replacement alternator is required, hopefully an expert will be along shortly to assist in more detail.

[X5Sport]

If the car was awake when he applied the multimeter leads then it’s not the volts to worry about, it’s the up to 70A DC flowing in whatever main power circuit he was trying. You need very heavy leads for that! These cars draw significant current when awake due to the computers all being up and running. Different options mean more or less current flow. This is why these cars start shutting services down without the engine running.

Trying to measure that current with small leads WILL burn them out. It’s why an auto-electrician should have been using a current clamp! You don’t connect a multimeter directly into the power circuit for a current check! 14V with the car off is wrong anyway, the battery will only show 12.8V at 100% charged and brand new.

Even with the car asleep, you have the alarm running so there will always be a small draw.

If the alternator fix doesn’t work, then the way to find the problem is unfortunately by pulling fuses until the draw disappears - but remember the alarm will draw something. If you have ConnectedDrive working, that is also awake all the time.

80mA is normal on these cars.

[Wayfarer]

Suspect that burning out two sets of leads will likley have damaged the meter, or certainly knocked its calibration Check the voltage across the battery terminals on a fully charged good condition agm battery with the engine not running it should be around 12.8 volts DC as below, if its reading 14v then the meter is poorly or out of cal.

A. State of Charge
1. Sealed or Flooded Lead Acid battery voltage
2. Gel battery voltage
3. AGM battery voltage
A. 1. 2. 3.
100% 12.70+ 12.85+ 12.80+
75% 12.40 12.65 12.60
50% 12.20 12.35 12.30
25% 12.00 12.00 12.00
0% 11.80 11.80 11.80


However if the battery doesn't loose any charge with the alternator disconnected, with everything else as normal. But discharges when alternator connected then it has to be the alternator, voltage reg or diode block, unless BMW have something else that switches on thats related to the charging circuit.
Good luck and hope you find the cause and it's an easy fix.

[Leslie]

I know 2 people who had alterators repaired on ford focus's only to have a similar issue where the battery was drained flat overnight afterwards so it could certainly be the alternator . I guess if it lasts 72 hrs and starts ok and you reconnect it and its flat next day you have the answer but as said you may only need to swap part of it out for a fix.

[Straycat_67]

48 hours since disconnecting to positive lead from under the bonnet which takes out the alternator, car unlocks fine with fobs, interior lights, hazards all working as they should, no dimming. So far so good, not willing to try and reconnect to start yet though, want to leave it another 36-48 hours. Taking into account the battery was going 100% flat within 36-48 hours with the under bonnet positive connected. Touch wood it's the alternator.

Like I may have said, unfortunately my mobile auto electrician gave me 2 contacts for alternator replacement but both are closed because of you know what, so will have to ring around Monday. Shout out's to anyone who might know of anyone that can supply and fit an alternator around my way? SK9 just south of Manchester here.

IF I do go the BMW main dealer route for supply and fit, can anyone give me any idea how much they are going to charge (I know it's going to be horrendous via them) but just want to get an idea.

Cheers everyone and stay safe!

[marti]

I'll just go off piste ...Does your vehicle have the IBS (intelligent battery sensor) , if so it is located to the negative lead on the battery, normally on the back of the clamp, unplug the connector...Ive just had this happen, so I unplugged it and no more drain...been unplugged for 2 weeks and all is well...a new one costs £250 ish .

[X5Sport]

Realoem will give you an indication of price in dollars. You’ll need the last 7 of your VIN (put in serial number box) to pull up the right car. There are two alternator versions dependant upon what options you have. 180A or 230A are fitted. If you have 4-zone climate then you need the higher power one.

On line they are up to £500 (that’s for a Valeo 230A). BMW will want more than that, and around here my Dealer charges £200/hr plus VAT.

Remanufactured units will be cheaper, but BMW won't offer you that!

[Straycat_67]

I'll just go off piste ...Does your vehicle have the IBS (intelligent battery sensor) , if so it is located to the negative lead on the battery, normally on the back of the clamp, unplug the connector...Ive just had this happen, so I unplugged it and no more drain...been unplugged for 2 weeks and all is well...a new one costs £250 ish .

But if i've disconnected the live terminal under the bonnet and I am no longer getting the drain could it still be the IBS. I presumed not...??? auto elec suggests it's most likely to be the alternator or starter motor coming on when supposed to be sleeping...??

[Straycat_67]

Realoem will give you an indication of price in dollars. You’ll need the last 7 of your VIN (put in serial number box) to pull up the right car. There are two alternator versions dependant upon what options you have. 180A or 230A are fitted. If you have 4-zone climate then you need the higher power one.

On line they are up to £500 (that’s for a Valeo 230A). BMW will want more than that, and around here my Dealer charges £200/hr plus VAT.

Remanufactured units will be cheaper, but BMW won't offer you that!

I'm seeing various prices online for a new alternator be it Bosch, Lucas etc... and they range from £300 - £500 GENERALLY!


Yet when I do some online supply/fit garages they come in anything from £195 - £417, huge range!
* Just realised most of these online quotes include a "repair only", so is it feasible that most alternators can be repairs while you wait?

[X5Sport]

Once the alternator is off the car, then changing the regulator pack is pretty straightforward. Not sure about a while-you-wait as it may take a while to get the alternator out, repaired and refitted. I think the OEM may be either Bosch or Valeo.

Newtis.info is the copy of the BMW Service instructions if you want to see how simple/tricky the job is. For the N57 engine the procedure is here ...

https://www.newtis.info/tisv2/a/en/e71- ... s/EBgCDOPy

On my X6, the alternator is top right under the air intakes so may be a quick job to remove/refit. You do need a special tool to lock the tensioner - which helpfully is at the bottom of the engine! Gotta love BMW design engineers.

[marti]

I'll just go off piste ...Does your vehicle have the IBS (intelligent battery sensor) , if so it is located to the negative lead on the battery, normally on the back of the clamp, unplug the connector...Ive just had this happen, so I unplugged it and no more drain...been unplugged for 2 weeks and all is well...a new one costs £250 ish .

But if i've disconnected the live terminal under the bonnet and I am no longer getting the drain could it still be the IBS. I presumed not...??? auto elec suggests it's most likely to be the alternator or starter motor coming on when supposed to be sleeping...??

Well put the live back on and disconnect the IBS....you have nothing to lose.

[Straycat_67]

I'll just go off piste ...Does your vehicle have the IBS (intelligent battery sensor) , if so it is located to the negative lead on the battery, normally on the back of the clamp, unplug the connector...Ive just had this happen, so I unplugged it and no more drain...been unplugged for 2 weeks and all is well...a new one costs £250 ish .

But if i've disconnected the live terminal under the bonnet and I am no longer getting the drain could it still be the IBS. I presumed not...??? auto elec suggests it's most likely to be the alternator or starter motor coming on when supposed to be sleeping...??

Well put the live back on and disconnect the IBS....you have nothing to lose.

Can I just confirm with you: By putting the live terminal back on under the bonnet, does this have a bearing on the IBS? ie. the front terminal controls not just the starter motor and alternator BUT ALSO the IBS? Auto electrician told me it just takes out the alternator and starter motor, but may be he was not familiar with IBS.. i don't know! Nothing to lose, well I don't have a trickle charger and ideally do not want to jump start it from dead for the 4th time in 10 days unnecessarily (concerned about screwing up the battery).

* Just to confirm, the car was going to sleep as it should, tested multiple times. It's just that it was waking up randomly though the night/day, but initially it does go to sleep. Does this rule out the IBS or not?

It's now 4 days with the front live terminal disconnected and so far so good with interior lights and other accessories not seeming dim or loss of power.

[X5Sport]

The IBS is part of the connections at the battery end......

https://www.newtis.info/tisv2/a/en/e71- ... y/1LyvW9MF

Note the comment about error codes. Have you had the fault code log read to see if anything is logged there? It should not be done with a generic code reader as they cannot always decode the BMW fault types correctly and send you on a wild goose chase.

[Straycat_67]

The IBS is part of the connections at the battery end......

https://www.newtis.info/tisv2/a/en/e71- ... y/1LyvW9MF

Note the comment about error codes. Have you had the fault code log read to see if anything is logged there? It should not be done with a generic code reader as they cannot always decode the BMW fault types correctly and send you on a wild goose chase.

Yes, I understand it's the blue connector at the negative battery terminal, my questions is, would it be a fault of the IBS as a source of high drain IF as I say my car is going to sleep as it should BUT waking up randomly when unattended.

No formal code reader has been used. Don't know anyone local other than main dealer and trying to avoid main dealer