[jwq2]

yes, the charge current should go through the IBS sensor, not directly to battery negative terminal, otherwise the charge status as reported by the IBS will not be correct, causing an incorrect charge strategy for the alternator during normal use.

 

[jwq2]

An "easy" foolproof way is to just connect the negative charge lead to a chassis point......
example ( I drilled a hole, but you could also use the square hole with a nut/bolt and washer) :

2nd picture is using the nut on the negative clamp as in the earlier pic, next to vertical post (so NOT 2a / 3a in pic)

 

[jwq2]

Sorry, this statement confused me.
If the car is not running, but only being charged, the ibs system should not be affected.
The car is not running, so the alternator is not charging.
When you disconnect the charger and start the vehicle, THEN the ibs system should regulate the charge from the alternator.

Yes, but the IBS needs to keep track of the charge going into and out of the battery at all times to have an accurate SoC (State of Charge), and with the engine subsequently running control the intelligent alternator to charge the battery as required according to the SoC according to the IBS

This should include any charge put into the battery by (trickle) charger, otherwise the reported SoC would be too low

It would correct after some time, but for a couple of days SoC would be incorrect if you do not account for external charging

 

[jwq2]

Thanks! I think connecting it to the chassis is definitely the easier way to go. So connecting it to the chassis will also make the current go through the IBS sensor? I already tried to unscrew that nut in the 2nd pic and it will not move. I'm afraid if I force it I might break the sensor. Will I need to disconnect the entire negative terminal? Or can I just undo the nut that the connection is connected to right now (3A in the 2nd pic), take the comfort connect negative connection out, then just screw the nut back in?

All users in the car use chassis as ground, so yes, current goes through the IBS when using chassis as ground. This is similar to connecting via the jumpstart terminals under the hood......

Be carefull with the nuts on the negative terminal, see warnings in service doc. As said, using a connection to chassis is a lot safer :

 

[jwq2]

....... Once the motor starts, it assess charge of the battery and regulates the alternator.

No, it doesn't work like that, the IBS sensor measures current going into and out of battery and has a memory that keeps track of the SoC over time etc, see :

 

[jwq2]

Curious is it better that the ibs doesnt see the battery as fully charged and bypassing it is favorable for charging more like the old days then?

People have tried to bypass or remove it to improve charging, but that didn't work. It will generate an error, and go into a failsafe mode which results in actually charging less .....
Same as disconnecting the battery for a short time.

<snip>
When the IBS is powered up for the first time or is powered after a power disconnection, it enters a
“recalibration” phase, where the IBS must recognize the type of battery and its characteristics and state. In
this phase the tolerances on the state functions (SOC, SOF) are greater than in normal working condition.
When IBS is disconnected from the battery, the device loses its stored memory. When power is restored,
the IBS starts a relearn process. Until the relearn process is complete, accurate battery state information is
unavailable to other vehicle systems. The IBS relearn process requires one start and at least 4 hours of
quiescent time (vehicle off, electrical system asleep). Remember, the relearn process is restarted every
time power is reconnected to the IBS. This has a major effect on the stop/start feature.

 

[jwq2]

Appreciate the info. My question is morecabout curiosity if you have the ground on the trickle charger connected to the battery post connector do you end up charging the battery to full capacity but ibs doesnt see it so it continues to charge at the higher rate it would have been?

in both cases, going via the IBS or direct to battery terminal, you will fully charge the battery as charging is determined by the connected charger.
However, if you then subsequently use the car, if you've charged via the IBS the IBS is aware that the battery is now fully charged, and will control charging accordingly.
If you directly connected to battery negative post, the battery will be also fully charged, but IBS will be unaware of this, and assume charge is still as determined when car was last used (so probably low battery charge), so will probably start charging. The IBS will at some point "see" that battery and IBS SoC do not match, and start recallibration, in the meantime using safe "failsafe" values.....

 

[jwq2]

Interesting. Not sure which was is better.

I suspect going via IBS is better for your battery, as it prevents overcharging, even if for a short while.
Best would be updated software that maintains a higher battery charge level

We're not the only ones though, I see a lot of problems with IBS on other fora from BMW, Mercedes etc.etc.

 

[jwq2]

I have the CTEK MXS10 and the comfort connect with indicator/green,yellow,red lights/.The dealer made the connections exactly as stated in the manual. The charger works great.On the original EFB battery- around 5-6 hours for complete charging. I changed the battery with AGM, because of superstition and now the whole charging process is even shorter - around 3-4 hours. The strange thing is how the indicator is working.It is only green, after charging and on the next 1,2 days.After this, it is always yellow or red. This was with EFB and now with the AGM is the same. Both batteries are new and in excellent condition. So, the indicator I think is not very accurate on the real condition of the battery ,anyway.

Basically it's a relatively simple voltmeter, so don't expect too much

The led's are apparently activated at the following voltages:
Green: above 12,65V
Yellow: 12,4 – 12,65V
Red: below 12,4V

As the IBS will never fully charge the battery, it's normal the indicator will stabelise after couple of days at yellow/red

normal:

State of Charge	Sealed or Flooded Lead Acid battery voltage	AGM battery voltage
100%	12.70+	12.80+
75%	12.40	12.60
50%	12.20	12.30
25%	12.00	12.00

 

[jwq2]

@jwq2, what about the positive end of the Comfort Connect cable?. Where to connect it to the battery?. When I take off the black plastic cover on top of the positive post of the battery, there are several nuts there (below picture). What nut should I choose to put the positive end of the Comfort Connect cable?

I simply used the following, but basically any connection directly to battery plus is ok

 

[jwq2]

It was a long time since I installed, so I'm not sure. It was the standard eyelet that came with the charger though.....
You could always measure the boltsize on the battery