[Watsey]

Originally Posted by Eddamoo

Ahh that may indicate your Battery is dead then. The batteries in our cars are 90-95AH. Just a 40% additional charge to a 95AH battery = 38AH. So your CTEK charger would have needed to take 7.6hours to charge it - probably even more as the 5A may not be continuous.

I would first try cleaning both the male and female terminals. I know our batteries are well protected in the boot, but resistance caused by a bad connection could cause issues.

It does look like I need to get to the battery directly and inspect a few things.

Today I made a return journey of around 50 miles each way, mostly motorway, and the battery SoC increased by 3% each way (finished at 43%). That seems to indicate there's a significant problem somewhere - alternator, IBS, terminals, or the battery itself.

[Watsey]

Update...

Strange goings-on with the battery and the data.

After my 100 mile round trip journey yesterday BimmerLink showed the SoC at 43%, which is obviously extremely low.

Today I did various checks :
Battery voltage at 'rest' (i.e. engine not running) was 13.6V.
Started the engine. Alternator output was 17.6V.
Voltage at the primary connections to the battery, engine running, was 17.5V (therefore the alternator output is reaching the battery).
Switched the engine off.
Disconnected the IBS, waited ~30 seconds, then reconnected.
Checked the SoC using BimmerLink. 52%.
Registered the battery again, using BimmerLink.
SoC then displayed as 72%.
Went for a 6 mile round trip drive, using manual mode to keep the revs between 1500-2000rpm so the alternator could work effectively.
SoC now shows as 79%.

Obviously I'll keep an eye on it but even though BimmerLink shows that I definitely registered the battery when it was first installed, perhaps the IBS didn't update correctly for some unknown reason.

[Eddamoo]

Ive never seen a 12V lead acid battery exceed 12.9V resting. My MayPole charger can only get them that high. 12.85V+ should equal 100% SOC.(https://sunonbattery.com/agm-battery-voltage-capacity/).

Im also surprised the alternator is pushing 17.6V! Most cars charge around 14.5V and thats what i typically see on the Onboard Display (you can see it when you unlock the service functions).

If you're seeing 17+ with both the multimeter and car, something doesnt seem to be right. Do you have any high voltage errors when doing an error scan?

You could potentially have a defective voltage regulator on the Alternator that is killing the battery.

[Watsey]

Originally Posted by Eddamoo

Ive never seen a 12V lead acid battery exceed 12.9V resting. My MayPole charger can only get them that high. 12.85V+ should equal 100% SOC.(https://sunonbattery.com/agm-battery-voltage-capacity/).

Im also surprised the alternator is pushing 17.6V! Most cars charge around 14.5V and thats what i typically see on the Onboard Display (you can see it when you unlock the service functions).

If you're seeing 17+ with both the multimeter and car, something doesnt seem to be right. Do you have any high voltage errors when doing an error scan?

You could potentially have a defective voltage regulator on the Alternator that is killing the battery.

Good point about the alternator - thanks. It's quite tucked away so I measured the voltage from the positive terminal and the chassis ground which is used if jump starting the car (or to charge the battery). Is that OK ?

No error codes when interrogating the ECUs with BimmerLink. Looks like more investigation is needed.

[TurboWeasel]

Strange voltages indeed. Especially 13.6V with the engine off.

Did you try it across the battery terminals with the positive cable removed? I know that will reset some adaptations.....but it should at least give a true reading of the battery itself.

I'm suspecting an iffy alternator as well. You could put your meter across it's output wire and the casing as the engine is grounded, which is a bit easier and quicker. You could also try it on the bodyshell ground point as well just to make sure there's no strange voltage drops through the engine's ground strap.

[Eddamoo]

Just popped out to my car to have a look at the voltages for a comparison. Resting was 12.2V at the battery (ECU, Dashboard and Boot light will have been on).

Car Running - they were within 0.1v between low and highish drain (lights, fans, bum warmers)

Measured at the Jump start terminal and earth: 15.31V
Measured at the Battery: 15.22V

Still higher than i expected. Last week the OBC definitely was showing 14.5V

[NanasBack]

Definitley something wrong there...

I don't think you should ever see 17+ volts anywhere.
14.7V is a normal max charging voltage.

Around 12.6V not charging is really good but more likely to be 12.3V or thereabouts.

Maybe check the meter you are using.
Is it reliable?

[danb1979]

Always thought that battery voltages should be c14.4v with engine running and c12.4v with engine off/car asleep

Either way, lower than those ball park figures, there's an issue somewhere unfortunately

[Watsey]

I had an interesting conversation with a respected BMW Indy this afternoon. They’ve worked on the car a few times in the past, are very knowledgeable, and did a good job.

I described the symptoms and what I’d found, i.e. multimeter readings and diagnostics.

In their experience :

• These cars are very sensitive in terms of battery selection. They’ve resolved a LOT of similar problems by removing a customer-fit battery and reinstating it with a genuine BMW unit even though ostensibly they are the same Ah etc. They suspect that the IBS reads the SoC data differently. It’s not clear whether the battery has an integrated BMS or something similar.
• The IBS itself, either the cabling or the programming, can be problematic / truculent.
• Alternator voltage regulators can fail, but in their opinion a 100K mile car is still ‘young’ and they don’t see a lot of alternator failures.
• A software update may be required but that would erase the remap. I’m not keen on that option.

Next steps are to get the car in to the Indy for a full investigation, using ISTA step-by-step diagnosis sequences.

[Watsey]

I did a couple more checks with my digital multimeter.

Our KIA Sorento, engine off, battery voltage was displayed as 13.4V

My F31, engine running, attaching to the alternator + terminal and the alternator body = 16.9V.

If 12V AGM batteries are meant to be around 12.4V then maybe the multimeter was over-reading by around 1V.

I tested some small appliance chargers :
18V output charger, multimeter reading was 20.8V (15% over-reading)
5V output charger, multimeter reading was 5.7V (14% over-reading)

Although it's not obvious that there's an internal battery I opened the multimeter case (just a couple of retaining screws) and, behold, there's a 9V battery. I expect it's at least 10 years old.

Replaced it with a super long life commercial grade 9V Duracell ProCell battery which is still giving 9.28V after 10 years (I use these batteries as the internal backup units for our interconnected mains-powered smoke alarms at home). The old internal 9V battery was giving 7.2V. Now the penny has dropped I expect these digital multimeters use an internal battery as a reference voltage and then calculate from there. Every day's a school day.

Checked the voltages again.

18V output charger, multimeter reading was 18.1V
5V output charger, multimeter reading was 5.1V
Sorento battery, engine off = 12.35V
BMW alternator = 15.3V
BMW battery (engine off) measured at the jump start terminals = 11.95V (not worried about that - there could easily be a 0.5V drop through the wiring).

It still doesn't solve the low SoC. Currently I'm suspecting an incompatibility between the Bosch battery and the IBS, or a problem with the IBS itself. Either way, I'm going to replace the battery with a genuine OEM unit. They are, surprisingly, no more than I recently paid for a new battery for the Sorento.

[danb1979]

Originally Posted by Watsey

I did a couple more checks with my digital multimeter.

Our KIA Sorento, engine off, battery voltage was displayed as 13.4V

My F31, engine running, attaching to the alternator + terminal and the alternator body = 16.9V.

If 12V AGM batteries are meant to be around 12.4V then maybe the multimeter was over-reading by around 1V.

I tested some small appliance chargers :
18V output charger, multimeter reading was 20.8V (15% over-reading)
5V output charger, multimeter reading was 5.7V (14% over-reading)

Although it's not obvious that there's an internal battery I opened the multimeter case (just a couple of retaining screws) and, behold, there's a 9V battery. I expect it's at least 10 years old.

Replaced it with a super long life commercial grade 9V Duracell ProCell battery which is still giving 9.28V after 10 years (I use these batteries as the internal backup units for our interconnected mains-powered smoke alarms at home). The old internal 9V battery was giving 7.2V. Now the penny has dropped I expect these digital multimeters use an internal battery as a reference voltage and then calculate from there. Every day's a school day.

Checked the voltages again.

18V output charger, multimeter reading was 18.1V
5V output charger, multimeter reading was 5.1V
Sorento battery, engine off = 12.35V
BMW alternator = 15.3V
BMW battery (engine off) measured at the jump start terminals = 11.95V (not worried about that - there could easily be a 0.5V drop through the wiring).

It still doesn't solve the low SoC. Currently I'm suspecting an incompatibility between the Bosch battery and the IBS, or a problem with the IBS itself. Either way, I'm going to replace the battery with a genuine OEM unit. They are, surprisingly, no more than I recently paid for a new battery for the Sorento.

Car electrics are not my forte

But how can moving from a non OEM battery to an OEM battery sort this; surely this would point more towards the IBS going duff?

My previous F01 had IBS issues; kept getting the 'battery draining whilst stationary' warning even after fitting a brand new Exide AGM battery, properly registered to the car etc and on trickle...

Replaced the IBS - never came back

[Watsey]

Originally Posted by danb1979

Car electrics are not my forte

But how can moving from a non OEM battery to an OEM battery sort this; surely this would point more towards the IBS going duff?

My previous F01 had IBS issues; kept getting the 'battery draining whilst stationary' warning even after fitting a brand new Exide AGM battery, properly registered to the car etc and on trickle...

Replaced the IBS - never came back

I was guided by A1 German Car Company (Stevenage) - really knowledgable guys, and they've worked on the car previously. As per my previous Post, they've seen "loads" of BMWs and Mercedes battery/charging/SoC problems cured by installing a genuine OEM battery.

Good point about the IBS though. Maybe I'll replace that first.

[NanasBack]

So the multimeter is no longer telling porkies.
That's good.

Another possibility concerning the battery.
Can you be sure it was fully charged when it was originally fitted?

You have checked it was registered so should still be pretty good for its age.
The car charging system never fully charges it and gradually reduces the charge over time, creating a falling soc.

I would suggest using your Ctek charger again once, to fully charge it over night, but connect it directly to the battery. Not the other side of the IBS where it tells you to.

See how it measures up over the next few days / weeks.
Might save the cost of a new battery so soon.

[Watsey]

Almost certain I fully charged the battery before installing it.

It’s being charged now, direct connection.

Once it’s done is it advisable to disconnect/reconnect the IBS to reset it, or just leave it altogether be but take a SoC reading using BimmerLink to see what SoC value the car is reporting ?

[NanasBack]

As far as I can make out, the IBS measures battery voltage, current and temperature, makes some calculations and then passes the data to the DME when the car is on.

It also measures battery volts, temperature and discharge current, every 14s when the car is off.

I don't know for sure, but I doubt disconnection / reconnection would achieve much other than possibly generate fault codes, particularly if it happened to be talking to the DME at the time..

It compares it's values of SoH and SoC with the DME.



It's a sensitive little fellow, looking at the list of Do Nots though.....
I would just monitor the values for a while.

[Allworth]

Time for a new battery

[Watsey]

After a full charge overnight (which took several hours) BimmerLink still only shows a SoC of 47%

Looks to me like the IBS is the #1 culprit.

AFAIK the IBS is only in the negative cable/connector at the battery. Correct ?

The part number is easy to find in realoem and AutoDoc (just an example) has several options showing, only one of which states that it needs to be coded.

https://www.autodoc.co.uk/spares-sea...rd=61219117877

[NanasBack]

Was the car driven before using Bimmerlink?

It needs some time to monitor the starting current, normal load, battery volts etc.

It won't know anything about what has been put into the battery overnight.
Does it start ok or does it struggle?

Battery on my car measured 50% SoH / SoC two years ago.
With the occasional overnight use of Ctek in the cold months, it still works fine.
(I hope I haven't jinxed in now).

[Watsey]

Originally Posted by NanasBack

Was the car driven before using Bimmerlink?

=> No

It needs some time to monitor the starting current, normal load, battery volts etc.

=>

It won't know anything about what has been put into the battery overnight.
Does it start ok or does it struggle?

=> Occasionally, but absolutely fine after a full charge. This is suggesting to me that the battery is not being adequately charged while the car is being driven.

Battery on my car measured 50% SoH / SoC two years ago.
With the occasional overnight use of Ctek in the cold months, it still works fine.

=> interesting to read, but alternator recharging seems to be very low in my car.

Thanks. Added my comments.

[Watsey]

Update :

There have been more instances where the engine wouldn’t start and I’ve had to use my jump-start pack. BimmerLink showed the battery SoC as low as 40%, and only 50% after a full charge using my CTEK.

I finally got round to ordering and replacing the IBS cable (£120 Autodoc) today. The SoC was displayed as 59% and with the new cable BimmerLink instantly shows the SoC as 99%. This,of course, is too high.

Presumably the data from the faulty IBS has interrupted the engine start cycle (as the car believes the battery doesn’t have sufficient charge, but also that the battery was being over-charged because the IBS has been reporting a low SoC. Hooefully the battery life hasn’t been degraded.

Replacing the cable was pretty easy as the chassis mounting point is located at the top/rear of the battery compartment - no need to remove the battery.

[Allworth]

Originally Posted by Watsey

Update :

There have been more instances where the engine wouldn’t start and I’ve had to use my jump-start pack. BimmerLink showed the battery SoC as low as 40%, and only 50% after a full charge using my CTEK.

I finally got round to ordering and replacing the IBS cable (£120 Autodoc) today. The SoC was displayed as 59% and with the new cable BimmerLink instantly shows the SoC as 99%. This,of course, is too high.

Presumably the data from the faulty IBS has interrupted the engine start cycle (as the car believes the battery doesn’t have sufficient charge, but also that the battery was being over-charged because the IBS has been reporting a low SoC. Hooefully the battery life hasn’t been degraded.

Replacing the cable was pretty easy as the chassis mounting point is located at the top/rear of the battery compartment - no need to remove the battery.

This is really an issue with new cars, when SoC is low it would cut off engine cranking completely after some point, whereas with the old cars it would crank until the battery is empty. What's bad is the cut off point is too soon on some cars with no prior warning

[Kendo67]

Originally Posted by Allworth

What's bad is the cut off point is too soon on some cars with no prior warning

The Li-Ion battery in the Porsche does that , below a pre-determined voltage the electronics within the battery deem it knackered and wont allow it to be charged , only proper solution is to have it taken to the dealer for replacement and registration.

Luckily the above is a cheap repair at a measly £1200 for the battery , fitting / coding and VAT take the replacement cost to just over £2k. Never saw that coming when i bought the Cayenne.

The selling point for the Li-Ion battery is that it is a "lightweight" battery , saving a whopping 5kg over a AGM battery , may make a difference in a GT3 RS on the "Ring" but not in a 2T SUV going to Morrisons for a pint of milk.

K