[mingqing007]

My F30 320d is 1.5 years old and recently I've notived that the battery voltage is always around 12.3+V.

One is measured by a multimeter before my vacation and the other one is measured by Battery-Guard the nextday after 500km drive home.

BTW, I rarely drive in ECO mode and always turn Auto-Start-Stop off. I've also measured a few times in between, always around 12.3+V. Also, when measuring the voltage using Battery Guard APP, I do that before start-up and without unlocking the car.

The third graph is from the Internet for references. What is the case with you guys, is my battery voltage normal?

[Mr Podman]

You're fine.

You run in eco mode so you can save gas but have your starter motor suck your battery and wear itself out at every traffic stop.

For your own curiosity, measure battery voltage while the car is running. If you see readings around 14 volts it means your charging system is working properly.

[mingqing007]

Originally Posted by Mr Podman

You're fine.

You run in eco mode so you can save gas but have your starter motor suck your battery and wear itself out at every traffic stop.

For your own curiosity, measure battery voltage while the car is running. If you see readings around 14 volts it means your charging system is working properly.

Actually I don't turn on ECO mode that often and I've coded Auto-Start-Stop off (remember last setting).

[Sigtran]

Having similar issue, 12.2V after few hours from turning car off, car is just 2 years old. Doing regular daily commute of totally ~1-1.5hr of suburban/urban driving to work and back. Always comfort mode, start-stop deactivated.

No any issues so far, but wondering when temps go into -10C or lower in month or two, will the car start with such low SoC.

During drive, voltage is between 14.7 and 14.9V, so alternator seems to be working OK, however not sure with how much current is it charging... And if all working correctly, why so low battery voltage and SoC?

[Wgosma]

You can use the 'hidden menu' in the cars OBC/instrument cluster to look at battery/charging system values, no need for multi meter. Search on YouTube for F30/F-Series hidden menu, see link. . Unlock and you can scroll thru and read system voltage, coolant temp and various parameters. Very convenient tool.

[HighlandPete]

Interesting topic, I assume we all know that the SoC with BMW's energy management and intelligent alternator control, is not targeted at 100%, even after a long run. Typically we run in the 70 - 80% range, allowance for 'over-run' regeneration. Not much over-run harvesting, SoC stays at a lower state. In fact we may drop out of that level, if using too many ancillaries and energy demands are not replenished within the alternator control. Then we go to a conventional charging phase, to get back to the 70 - 80% state.

If we run with a voltmeter active, we may notice the 14.4V steady state increases to 14.7V on the over-run, this is a sign we are in the 70 - 80% SoC range (or above) and the battery is charging in the over-run state.

If we charge the battery, SoC soon reduces, no alternator charging as such, (balance of battery use and alternator support) to allow battery capacity for the over-run charging.

I'm monitoring my battery at the present time, and seeing how the SoC is influenced by daily and less frequent use.

I've done this before, and typically the voltage settles to ~12.3 - 12.4 Volts, when in the sleep mode after use. Same last winter, mid summer and at the present time.

I charged my battery last Tuesday and then used my car every day, 25 - 30 miles, including a couple of starts along the way. Sunday after use, the battery was reading 12.4 Volts in sleep mode.

I've also been driving slightly different to get maximum energy harvesting on the over-run. To see if this will keep the SoC in a higher state. Even after two long runs, (both over 60 miles) the battery wasn't "charged up", still reading similar voltage to what I typically see.

That's energy management for you!

[rparnel1]

I generally dont drive mine on the weekend as its a work car. I put it on a battery tender on Friday and it usually takes about 12 to 24 hours for it to cycle to float. Makes me think that the charging system never really brings battery to 100%.

[HighlandPete]

Originally Posted by rparnel1

I generally dont drive mine on the weekend as its a work car. I put it on a battery tender on Friday and it usually takes about 12 to 24 hours for it to cycle to float. Makes me think that the charging system never really brings battery to 100%.

Even if you start out with 100% SoC, charge will almost certainly go down with driving, as the alternator won't be charging except on the over-run, therefore won't keep the battery full. Unless you have miles of over-run driving.

Intelligent alternator control (IGR), isn't designed to keep a battery at 100%. The following from BMW data:

Energy recuperation
Fuel consumption is reduced by way of energy recuperation in favourable vehicle operating modes (overrun phases) based on a request to increase the alternator voltage (target values). This energy recovered without the use of fuel is stored in a "receptive battery". The charge status of the battery must be within certain levels that permit charging. A fully charged battery (100 % charged) cannot accept energy and is therefore avoided as part of the intelligent alternator control strategy.

The "within certain levels...".

In contrast to conventional charge control, the intelligent battery control avoids a 100% charge. The charge level of the battery reaches about 70 - 80% of the maximum possible charge.

The intelligent alternator control is suppressed cyclically in order to allow 100% battery charge to maintain the full capacity of the battery over time (regeneration).

[Sigtran]

Issue is that battery is not kept at 70-80%, but 12.3V is ~50% SoC... And sometimes is just 12.2AV. All that now at +20C outside temp. In month or two it shall be -10C, sometimes even -15C in the morning, will the car start if such low SoC is kept by "inteligent battery management"?

"The intelligent alternator control is suppressed cyclically in order to allow 100% battery charge to maintain the full capacity of the battery over time (regeneration)."???

I have never seen above 12.4V (after night sleep) even after 800km day trip. Does anyone ever get more?

By contast, my wife car (not BMW), is typically at ~12.7V (similar age battery, also AGM - healthy 100%, measured full rated CCA, similar internalR). My daily trip to work is at least 1hr (~35km round trip through rush hours), and of my wife is even less.

BTW this battery tester is fully aware battery is AGM type (selected on battery test start) and not a regular type.

[zeikei]

Here in the north it is common to get your car coded to disable the brake energy regeneration stuff so that battery would be charged to 100% but I am not sure if it truly works like that. In any case during winter I would rather have my battery in top shape than save a drop of fuel. Mine has been coded like that so I will check my voltages.

[Sigtran]

Originally Posted by zeikei

Here in the north it is common to get your car coded to disable the brake energy regeneration stuff so that battery would be charged to 100% but I am not sure if it truly works like that

I am not aware it is possible to use coding to disable BMW's Brake Energy Regeneration system and to force system to charge battery up to 100%... I've "googled" about this topic and there is no info to be found to support such idea, at least not for BMW brand.

[HighlandPete]

Originally Posted by Sigtran

Issue is that battery is not kept at 70-80%, but 12.3V is ~50% SoC... And sometimes is just 12.2AV. All that now at +20C outside temp. In month or two it shall be -10C, sometimes even -15C in the morning, will the car start if such low SoC is kept by "inteligent battery management"?

"The intelligent alternator control is suppressed cyclically in order to allow 100% battery charge to maintain the full capacity of the battery over time (regeneration)."???

I have never seen above 12.4V (after night sleep) even after 800km day trip. Does anyone ever get more?.

Even after a charge, my battery typically settles at 12.3 to 12.4V (sleep mode), after driving around a few days of local use, (24 - 30 miles in a day). When I connect to a CTEK charger, the bulk phase usually completes quite quickly, sometimes within 30 minutes. CTEK state the bulk (step 3) charges to approximately 80% SoC, which would seem quite quick for the voltage I start with.

Your "???" for the intelligent alternator control comment. Are you questioning the battery must leave charging capacity, as part of the system design? Or are you reading the battery will be cyclically charged to 100%, (within the energy management), to extend the battery life?

I'm also interested in what other users find if checking the sleeping voltage. I take my readings from the front jump start terminals. Driving profile may make a difference, particularly if a user does an lot of over-runs, which keep topping up the SoC.

[zeikei]

Originally Posted by Sigtran

I am not aware it is possible to use coding to disable BMW's Brake Energy Regeneration system and to force system to charge battery up to 100%... I've "googled" about this topic and there is no info to be found to support such idea, at least not for BMW brand.

I can try to find out what gets coded, I did not do it myself. In any case it is very common over here, especially for cars like mine which have an independent fuel operated heater (Webasto) as that uses battery when it operates.

I can see from my dash that it no longer goes to the blue charge area during engine braking, or in any situation for that matter. Whether it charges the battery to 100% I guess I can just hope it does

[Sigtran]

I still think battery management system on F30 is not so well designed...

This morning, before starting a car after not being driven for 5 days (I was on business trip), battery voltage was only 11.96V (outside temp ~+10C). Just two years old OEM battery. No chance battery is bad, actually it has decent (low) internal resistance of 4mOhm and good CCA, it just isn't charged. No any faults reported by car also.

It doesn't make sense that while doing enough driving, BMW recommend external charging - this really is not a premium experience! I owned AUDI for 5 years, doing same daily trips as now with F30 and never charged battery - and it was always well charged (typically between 12.4-12.5V), so not pushed to 100% charge but always kept above 50% charge level by its battery management system. F30 on other hand seems to keep below 12.3V, which is IMHO a bit to low to guarantee reliability when for example car is not being driven for a week or so and night temperature drops to -10C or lower... What is the point having 95Ah battery that is typically restrained to 25-30% charge level just to save some milliliter of fuel while risking reliability?

[bimmer456]

Have you had the system checked to see if it's working properly? My 2016 is still on the original battery which is pretty good considering other conventional charging system cars I've owned and daily driven and the battery was dead after 2 years. I live in SoCal so it never drops much below 40 degrees F. I have a battery tender but haven't used it consistently.

[Sigtran]

Originally Posted by bimmer456

Have you had the system checked to see if it's working properly?

Once, almost a year ago, I left it in garage for about 3 weeks, and afterwards car started but displayed warring something like battery low, please drive or do not turn off the engine... Later, I never saw such message again, but also never happened being parked for more then 4-5 days.

Anyhow, on BMW car diagnostic (Carly) it does not throw any errors. If I ask dealer he would ask me if I had problems starting the car, and I didn't have any problems (yet), and then he would put car on diagnostic, all would probably be ok.

To me it just look that SW is setup to charge battery as minimally as needed while saving as much fuel as possible.
And stupidly, as I know, there is no any option that behavior can be adjusted in any way.

[bimmer456]

Originally Posted by Sigtran

Once, almost a year ago, I left it in garage for about 3 weeks, and afterwards car started but displayed warring something like battery low, please drive or do not turn off the engine... Later, I never saw such message again, but also never happened being parked for more then 4-5 days.

Anyhow, on BMW car diagnostic (Carly) it does not throw any errors. If I ask dealer he would ask me if I had problems starting the car, and I didn't have any problems (yet), and then he would put car on diagnostic, all would probably be ok.

To me it just look that SW is setup to charge battery as minimally as needed while saving as much fuel as possible.
And stupidly, as I know, there is no any option that behavior can be adjusted in any way.

I don't use a volt meter just gauge if it seems to be starting fine and maybe put it on the maintainer from time to time. It usually doesn't take long to go to float charge.

[Sigtran]

Originally Posted by bimmer456

I don't use a volt meter just gauge if it seems to be starting fine and maybe put it on the maintainer from time to time. It usually doesn't take long to go to float charge.

It doesn't seem like a premium experience that premium brand owner have to put his car on external charge/maintainer every once in a while... Not written with small letters in car manual either.

IMHO, BMW should have given some choice of limited adjustment possibility through some hidden menus to adjust between "more fuel saving" or "more battery charge", within allowed safe limits of course.

[bimmer456]

Originally Posted by Sigtran

It doesn't seem like a premium experience that premium brand owner have to put his car on external charge/maintainer every once in a while... Not written with small letters in car manual either.

IMHO, BMW should have given some choice of limited adjustment possibility through some hidden menus to adjust between "more fuel saving" or "more battery charge", within allowed safe limits of course.

I just decided to get a maintainer but it probably would be fine if I never used it but if you're parking for a few weeks without driving I would use it.

[Wires]

Originally Posted by Sigtran

Once, almost a year ago, I left it in garage for about 3 weeks, and afterwards car started but displayed warring something like battery low, please drive or do not turn off the engine... Later, I never saw such message again, but also never happened being parked for more then 4-5 days.

Anyhow, on BMW car diagnostic (Carly) it does not throw any errors. If I ask dealer he would ask me if I had problems starting the car, and I didn't have any problems (yet), and then he would put car on diagnostic, all would probably be ok.

To me it just look that SW is setup to charge battery as minimally as needed while saving as much fuel as possible.
And stupidly, as I know, there is no any option that behavior can be adjusted in any way.

No disagreements with what you are saying. I left our car for 10 days on a business/vacation trip, and when I came back, the weather was -30C. Until I plugged in the trickle charger and let it run for the weekend to get it back to 100%, the car never recovered. First drive to work (20 minutes) I got the "don't turn off your car" warning. Drove another 30 minutes to our second work place, same warning.

I get the conservation of fuel, but if the battery is hitting a level that prompts the car to tell you that you're screwed, why isn't it charging more? Only thoughts is the alternator at low RPM's isn't putting out enough juice to do the job on a depleted battery.

[HighlandPete]

Originally Posted by Wires

No disagreements with what you are saying. I left our car for 10 days on a business/vacation trip, and when I came back, the weather was -30C. Until I plugged in the trickle charger and let it run for the weekend to get it back to 100%, the car never recovered. First drive to work (20 minutes) I got the "don't turn off your car" warning. Drove another 30 minutes to our second work place, same warning.

I get the conservation of fuel, but if the battery is hitting a level that prompts the car to tell you that you're screwed, why isn't it charging more? Only thoughts is the alternator at low RPM's isn't putting out enough juice to do the job on a depleted battery.

Has to be the use (or lack of) and the temperature.

My understanding, the intelligent alternator control changes to conventional charging mode at a defined low SOC, and/or when the temperature is too low.

Some of our driving profiles mean, even when conventionally charging, the battery doesn't recover the SOC by very much, if at all, without plugging in a battery maintainer.

BMW's "certain level" for conventional charging to take over, isn't specified in any material I've access to. Say it is 60% SOC, that may well be too low for many users with more 'challenging' driving profiles.

Plus we must consider the electrical consumers we choose to use, can limit the alternator's ability to add charge to the battery. Alternator can be at full capacity (for the revs) and still make no real headway in charging the battery.

Then this is really no different than years ago, when winter energy demands could limit battery charging on our vehicles. I recall vehicles with ammeters, switch everything on and the gauge would swing to the negative side. You'd have to switch off consumers, to get some positive charge to the battery.

[Wires]

My case was most likely the cold temperature. You just cannot charge a cold battery as fast, but at the same token, I've never seen this with any other vehicle. Is it because it didn't happen, or just the vehicle didn't toss the ominous "you are going to be stranded soon!" message. Could be the latter, with BMW being more proactive with warning you.