[BavarianFanatic]

Originally Posted by Pyewacket69

I'm the first one to admit I'm not an electrical engineer, but as I understand the text below...

"The IBS is a mechatronic component for monitoring the battery condition. The IBS is secured and connected to the negative terminal of the battery. The power supply for the IBS is fed across a separate cable. For data transmission, the IBS is connected to the DME (Digital Engine Electronics) or DDE (Digital Diesel Electronics) via the BSD (bit-serial data interface).

The software in the PC-board of the IBS calculates State of Charge and State of Health of the battery and sends the information to the DME via the Bit Serial Data link. Off-load current measurement: When the vehicle is not in use, the IBS continuously monitors the data relevant to the battery indicators. The IBS is programmed to wake up every 14 seconds so that it can update the measured values with new measurements. The measuring time is approx. 50 milliseconds (ms). The measured data are entered in the IBS memory for monitoring the offload current. When the engine is restarted, the DME / DDE reads off the off-load current curve. In the event of a deviation from the definedoff-load current curve, an entry will be made in the DME / DDE fault memory."

...

As I read this, I get the impression that the IBS is monitoring the battery constantly, even in a ignition "off" situation.

Am I missing something?

It is monitoring while the car is off, but, it is measuring the "off load current" which is the current flowing THROUGH the sensor. When you connect directly to the battery terminals you are bypassing the sensor which means it will not see the charging current. When you charge via the underhood charge points the current does pass through the IBS so it is able to measure the charging current.

Again, if all you're doing is a maintenance charge with a tender, then it likely won't cause enough of an issue to notice. But, a deeper charge definitely will, especially if done repeatedly.

[Pyewacket69]

Originally Posted by BavarianFanatic

It is monitoring while the car is off, but, it is measuring the "off load current" which is the current flowing THROUGH the sensor. When you connect directly to the battery terminals you are bypassing the sensor which means it will not see the charging current. When you charge via the underhood charge points the current does pass through the IBS so it is able to measure the charging current.

Again, if all you're doing is a maintenance charge with a tender, then it likely won't cause enough of an issue to notice. But, a deeper charge definitely will, especially if done repeatedly.

I get your explanation, and I see your point.

Thanks!

[Pyewacket69]

Not to belabor the issue, but I also found this more detailed explanation:

-----

IBS MEASURING/EVALUATION FUNCTION
The measuring/evaluation function of the IBS electronics, continuously measures the following values under all vehicle operating conditions:

Voltage (6V to 16.5V)
Current (200A to +200A)
Closed Circuit Current (0A to 10A)
Starting Current (0A to 1000A)
Temperature (-40C to 105C)
When the vehicle is stationary, the IBS is programmed to wake up every 14 sec. and makes the required measurements within approx. 50 ms in order to save power. The measured values from the IBS are provided to the DME by way of the Binary Serial Data Interface (BSD) to calculate the State of Charge and State of Health for the battery.

State of Charge (SoC) is a calculated condition showing the current charge of the battery. SoC is used during key ?OFF? periods to insure the battery maintains a sufficient charge to start the engine at least one more time.
State of Health (SoH) tracks the history of the battery. Charge/dis-charge cycles and times are monitored. SoH helps the DME determine the proper charging rates and anticipated battery life. Internal resistance of the battery is calculated by the IBS from the current and voltage dip during engine start. The values are forwarded to the DME to calculate the SoH of the battery.

Software contained in the microprocessor of the IBS utilizes the measured values to calculate the State of Charge (SoC) of the battery during vehicle sleep mode and compares this information with that received from the DME/ECM pertaining to the battery SoC/SoH, during the period of time between engine ?OFF? and deactivation of the DME main relay.

The current SoC/battery data is stored in the IBS every 2 hours over a 6 hour time frame, providing 3-2 hour snapshots of battery SoC information. The stored information/snap-shot data is overwritten every 6 hours. Whenever KL15 is activated the IBS updates the DME with the current closed circuit histogram/battery status information, by way of the BSD. Upon obtaining updated information the DME evaluates the new data and if a closed-circuit current draw is identified a fault will be stored in the fault memory of the DME.

-----

Given this detail, isn't current draw only one of several measurements being made every few seconds?

At rest, with the ignition off, isn't he current draw going to be at its lowest?

[BTT 335i]

The best what you can do is go to your dealer and buy the original charger for your car, check the link
http://www.shopbmwusa.com/PRODUCT/16...nterId=4080801

[BavarianFanatic]

Originally Posted by Pyewacket69

Not to belabor the issue, but I also found this more detailed explanation:

-----

IBS MEASURING/EVALUATION FUNCTION
The measuring/evaluation function of the IBS electronics, continuously measures the following values under all vehicle operating conditions:

Voltage (6V to 16.5V)
Current (200A to +200A)
Closed Circuit Current (0A to 10A)
Starting Current (0A to 1000A)
Temperature (-40C to 105C)
When the vehicle is stationary, the IBS is programmed to wake up every 14 sec. and makes the required measurements within approx. 50 ms in order to save power. The measured values from the IBS are provided to the DME by way of the Binary Serial Data Interface (BSD) to calculate the State of Charge and State of Health for the battery.

State of Charge (SoC) is a calculated condition showing the current charge of the battery. SoC is used during key ?OFF? periods to insure the battery maintains a sufficient charge to start the engine at least one more time.
State of Health (SoH) tracks the history of the battery. Charge/dis-charge cycles and times are monitored. SoH helps the DME determine the proper charging rates and anticipated battery life. Internal resistance of the battery is calculated by the IBS from the current and voltage dip during engine start. The values are forwarded to the DME to calculate the SoH of the battery.

Software contained in the microprocessor of the IBS utilizes the measured values to calculate the State of Charge (SoC) of the battery during vehicle sleep mode and compares this information with that received from the DME/ECM pertaining to the battery SoC/SoH, during the period of time between engine ?OFF? and deactivation of the DME main relay.

The current SoC/battery data is stored in the IBS every 2 hours over a 6 hour time frame, providing 3-2 hour snapshots of battery SoC information. The stored information/snap-shot data is overwritten every 6 hours. Whenever KL15 is activated the IBS updates the DME with the current closed circuit histogram/battery status information, by way of the BSD. Upon obtaining updated information the DME evaluates the new data and if a closed-circuit current draw is identified a fault will be stored in the fault memory of the DME.

-----

Given this detail, isn't current draw only one of several measurements being made every few seconds?

At rest, with the ignition off, isn't he current draw going to be at its lowest?

Remember, we're specifically talking about charging the battery with an external charger. If you're not using the underhood posts the IBS will not recognize that you charged it and will therefore have an inaccurate SOC reading.

And to answer your questions, the IBS measures charge voltage and current. The SOC and SOH are simply calculated from these values. The current draw should be very low when the car is off. One of the primary functions of the IBS is to identify times when the current draw was more than expected so it can store a fault code or display a warning. There are several systems on the car that are energized on a regular basis to assess a multitude of different things (such as, has the car been tagged as stolen). Occasionally something happens that prevents one of these systems from sleeping which results in excessive discharging.

[DHS]

Originally Posted by Billfitz

+1. The point of a trickle charger is that even when off the car is using current, and if left unused and/or in cold conditions for extended periods the battery will discharge. A trickle charger will supply enough current so that doesn't happen.

If you use a trickle charger you will eventually overcharge the battery and ruin it.

[Billfitz]

Originally Posted by DHS

If you use a trickle charger you will eventually overcharge the battery and ruin it.

Myth. From the BMW charger link above: The device's on-board microchip monitors and regulate the charge- virtually eliminating sulfation. It can even help extend the life of your battery. That technology isn't unique to the BMW charger by any means. Older chargers that don't use microchip regulation are nonetheless still regulated.

The best what you can do is go to your dealer and buy the original charger for your car, check the link

The only thing which makes the BMW charger different from any other charger with similar specs is the BMW logo.

[DHS]

Originally Posted by Billfitz

Myth. From the BMW charger link above: The device's on-board microchip monitors and regulate the charge- virtually eliminating sulfation. It can even help extend the life of your battery. That technology isn't unique to the BMW charger by any means. Older chargers that don't use microchip regulation are nonetheless still regulated.
The only thing which makes the BMW charger different from any other charger with similar specs is the BMW logo.

You need to learn the difference between battery maintainer and trickle charger. There us a huge difference.

[Billfitz]

Originally Posted by DHS

You need to learn the difference between battery maintainer and trickle charger. There us a huge difference.

About the same difference as there is between Coke and Pepsi. Quite a few products use both names. For instance:
http://www.blackanddecker.com/produc...e-charger/bm3b
Technically speaking a true trickle charger can have a lower ampere rating, as it's only designed to provide enough current to account for the natural discharge rate of a battery with no load. Today that would apply mainly to a battery left sitting on a bench, or one in a tractor or boat that has no load on the battery when not in use. Modern cars never have no load on the battery, there's always something running that will drain a battery at a faster rate than the battery's own normal discharge over time. With a true trickle charger automatic shut-off isn't necessary, as the low current delivery is always offset by the inherent discharging of the battery. Such devices are very rare today, as electronic regulation is very inexpensive and therefore found in virtually all chargers whatever their current capacity.

[bobalston2]

Billfitz
Your post was very helpful about permanently connecting a charger to the BMW posts under the hood.
I never heard of "split loom" but guess I will need some.

I read somewhere that I needed to add a 6 mm bolt to the negative post to connect my CTEK 3300 charger "circle" connector.

But what do I need to connect the positive connector? I only found one picture of one inside the red plastic and it looks like I will need a nut of unknown size.
Do you know the size?

I think I will also need this extension cable to extend to the front grill.
https://www.fcpeuro.com/products/cte...IaAleVEALw_wcB


This is my wife's new care so I must take great care not to f--- it up.

Thanks

[Billfitz]

My cable is pretty much the same as the one you linked. The end that connects to my charger runs through the lower grille, held in place with a plastic zip tie. I cut off the connector on the other end. I spliced additional wire to that end of the cable to reach the positive and negative charging posts. I put 'U' connectors at the end of that wire. I created those from a pair of ring connectors, like these:


I loosened the charging posts, slid the U connectors under the posts, then tightened the posts again. You need a T-50Torx bit to loosen the posts.


I put an in-line fuse in the positive wire, close to the post. I secured the charger wiring to existing wiring under the hood with plastic wire loom, like this:
https://www.lowes.com/pd/Gardner-Ben...B&gclsrc=aw.ds
You can see the loom in the negative terminal picture.
Disconnect the battery negative terminal when attaching the leads to the posts. After re-connecting the only thing you may have to do is to reset the clock.

[bimmer456]

I use the BMW branded charger on my non BMW car with flooded cell type battery and it works fine. It is an OEM so not made by BMW that makes other battery maintainers under the Deltran brand in the US. Likely in Germany they have a Bosch maintainer they sell at the dealership.

[Musashi]

Originally Posted by BavarianFanatic

It is monitoring while the car is off, but, it is measuring the "off load current" which is the current flowing THROUGH the sensor. When you connect directly to the battery terminals you are bypassing the sensor which means it will not see the charging current. When you charge via the underhood charge points the current does pass through the IBS so it is able to measure the charging current.

Again, if all you're doing is a maintenance charge with a tender, then it likely won't cause enough of an issue to notice. But, a deeper charge definitely will, especially if done repeatedly.

we have been charging our cars, 14 combined years, 250,000 kms, via direct connection to the battery. As BMW owners I know. Although I understand quite a few things about batteries, SOC etc, not about the IBS. The catch to what I wrote, is that my city's two BMW dealerships installed all these chargers DIRECTLY to the battery. For us and every single BMW owners that I know. Therefore, either two dealerships have no clue as to what they are doing, or the IBS considerations are irrelevant should it measure actual SOC.

Keep in mind that we live in Canada, brutal cold for months, the batteries are nearly completely drained every 5 days of short commuting, and I recall charging the car at -45C for many many many days. no issues. I will buy a new charger, the CTEK, and I will connect it to the front- no issues there. It is very interesting the BMW service centres install them to the battery. Yet, also seen them hood-plugged in showrooms, quite the variety.

[Billfitz]

Since these chargers are self regulating there's no harm in connecting them to the battery directly. There's no benefit either.

[HighlandPete]

Originally Posted by Musashi

we have been charging our cars, 14 combined years, 250,000 kms, via direct connection to the battery. As BMW owners I know. Although I understand quite a few things about batteries, SOC etc, not about the IBS. The catch to what I wrote, is that my city's two BMW dealerships installed all these chargers DIRECTLY to the battery. For us and every single BMW owners that I know. Therefore, either two dealerships have no clue as to what they are doing, or the IBS considerations are irrelevant should it measure actual SOC.

Either the dealerships know something which works, contrary to what BMW recommend, or they are going against the typical BMW directive and are ignoring the consequences to battery life.

If the battery is to be charged while it is still installed, it must be charged using the jump start terminal points. Only then can you be sure that charging is correctly recognised by the vehicle electronics on vehicles with an intelligent battery sensor (IBS). If the battery is charged directly at the battery terminals, this could lead to a misinterpretation of the battery condition and even unwanted Check Control messages or fault entries. The cigarette lighter gets his voltage supply by the front power distribution box via the switched terminal 30B. After terminal 30B off, the relay de-energises. This means that a trickle charger connected at the cigarette lighter would be disconnected from the battery. Only charge the battery via the jump start terminal point.

[BavarianFanatic]

Originally Posted by Musashi

we have been charging our cars, 14 combined years, 250,000 kms, via direct connection to the battery. As BMW owners I know. Although I understand quite a few things about batteries, SOC etc, not about the IBS. The catch to what I wrote, is that my city's two BMW dealerships installed all these chargers DIRECTLY to the battery. For us and every single BMW owners that I know. Therefore, either two dealerships have no clue as to what they are doing, or the IBS considerations are irrelevant should it measure actual SOC.

Keep in mind that we live in Canada, brutal cold for months, the batteries are nearly completely drained every 5 days of short commuting, and I recall charging the car at -45C for many many many days. no issues. I will buy a new charger, the CTEK, and I will connect it to the front- no issues there. It is very interesting the BMW service centres install them to the battery. Yet, also seen them hood-plugged in showrooms, quite the variety.

The dealers are just taking the easy route. The thing to remember with contemporary BMWs is that they don't continuously charge the battery like they did in the old days. They charge when, and how much, the computer thinks they need to charge. The charging profile changes with the passing of time, based on the assumption that the battery's ability to accept a charge diminishes over time. This is precisely why a new battery needs to be "registered" in the car.

Functionally, there's no issue with charging the battery directly. But it will inevitably alter the car's charging profile over time and, in the end, potentially result in an undercharged state because it has no way of knowing the battery attained it's current level of charge via an external source.

[pshovest]

Originally Posted by Musashi

...........my city's two BMW dealerships installed all these chargers DIRECTLY to the battery...............

Please post photos of this installation showing both charger connection points. It is possible to install charger at battery and not bypass the IBS functionality.

[Musashi]

Originally Posted by pshovest

Please post photos of this installation showing both charger connection points. It is possible to install charger at battery and not bypass the IBS functionality.

As requested. Does not seem to pass the IBS. Which explains why, if charged at the front, it is green very fast, and, at the rear, takes twice as long. The IBS I think declares it charged at 50-75%. At the battery it charges it to the top.

[pshovest]

Great photos and it's good to see that the dealer did install it correctly.

The trick is to make the (-) connection to the chassis, not the battery terminal.

In your photo you can see the copper strip at the (-) terminal. This is a resistor the IBS/DME uses to measure voltage drop. Voltage drop across a known resistance allows DME to calculate the current that enters or leaves the battery. It integrates these current readings over time and can tell how many amp-hours have charged or discharged the battery and the resulting change in the battery's SOC. By knowing how much the battery's SOC has changed the DME can regulate the alternators output to maintain or raise the SOC.

If you hookup directly to battery you bypass the IBS monitoring, raise the battery's SOC and run the risk of the alternator over charging the battery until the next sleep cycle determines the battery's SOC.

There should be no difference between charging in the trunk or via underhood terminals. Both put charge directly into the battery (via the IBS) and there is no mechanism for the IBS to limit charging in this manner. Not sure why you see a difference in the charge lights. Sounds like your charger shuts off quicker (goes to green) using underhood terminals. Voltage drop from long cables or bad connection(s) underhood may be a factor.

[bimmer456]

Originally Posted by BavarianFanatic

The dealers are just taking the easy route. The thing to remember with contemporary BMWs is that they don't continuously charge the battery like they did in the old days. They charge when, and how much, the computer thinks they need to charge. The charging profile changes with the passing of time, based on the assumption that the battery's ability to accept a charge diminishes over time. This is precisely why a new battery needs to be "registered" in the car.

Functionally, there's no issue with charging the battery directly. But it will inevitably alter the car's charging profile over time and, in the end, potentially result in an undercharged state because it has no way of knowing the battery attained it's current level of charge via an external source.

I think the system should be able to detect the state of charge without knowing the age of the battery just by monitoring it and whether it can accept additional charge. My battery maintainer does this without knowing the age of the battery. Though I did see a new type of maintainer at the dealerships now that does this.