Pros, Cons to Removing IBS

[Mguy]

Ok dumb question which hopefully has a dumbed down answer. If the two batteries are connected in parallel why doesn’t the IBS “see them” as one slightly larger battery?

It ain't a dumb question at all. Unique among all devices in your alternator equipped JL, the IBS does not see the main and aux batteries in parallel because it's not wired to do so. It's shunt (measures current) is in series with only the main negative, it's thermistor (what else could it be) touches only the main. Voltage is a different story, and a big part of the reason "we" do the aux negative/F42 disconnect. Sorry if I didn't give the answer with the right dumbed down effect. Perhaps there's a good diagram out there.

Thanks for your compliments on that other thread, much appreciated. I'm not going back there. @mbrose1994 has started an interesting experiment, I'll be back here in a day or two.

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[THAW]

Ok dumb question which hopefully has a dumbed down answer. If the two batteries are connected in parallel why doesn’t the IBS “see them” as one slightly larger battery?

@Mguy is correct, and beat me to it, but...

The most "dumbed down" answer I can give is It has to do with where/how the IBS is attached (between a negative battery terminal and all electrical connections to it).

Technically, the IBS could be wired/positioned to monitor a composite of 2 parallel batteries (but definitely is not in the JL).

 

[Terrymo]

It ain't a dumb question at all. Unique among all devices in your alternator equipped JL, the IBS does not see the main and aux batteries in parallel because it's not wired to do so. It's shunt (measures current) is in series with only the main negative, it's thermistor (what else could it be) touches only the main. Voltage is a different story, and a big part of the reason "we" do the aux negative/F42 disconnect. Sorry if I didn't give the answer with the right dumbed down effect. Perhaps there's a good diagram out there.

Thanks for your compliments on that other thread, much appreciated. I'm not going back there. @mbrose1994 has started an interesting experiment, I'll be back here in a day or two.

Anything less than a 1000 word cut and pasted reply is a bonus. Thanks

 

[Jebiruph]

The author of post #5 in the thread you found is very knowledgeable about JL battery systems and electronics and has provided incredibly valuable information to the forum.

However, I don't agree with his guess (from 3 years ago) about the JL IBS and smart charging. The fact automotive "smart" charging existed before IBS technology was in regular use does not necessarily mean JL charging is designed to function without the IBS. The loss of IBS data for battery temperature, alone, could lead to battery damage.

In any case, if you go ahead with your plan, you should probably use JScan to set "IBS Present" to "Off", in case it actually makes a difference to a JL.

My IBS was disconnected for a while before I found the problem and my alternator still worked. Battery temperature is more critical to analyzing battery health than it is to charging the battery.

@mbrose1994 Leave it plugged in, there's no downside and it provides useful information on the health of the main battery.

 

[THAW]

My IBS was disconnected for a while before I found the problem and my alternator still worked. Battery temperature is more critical to analyzing battery health than it is to charging the battery.

@mbrose1994 Leave it plugged in, there's no downside and it provides useful information on the health of the main battery.

Yes, I assumed the vehicle/alternator would operate without the IBS, I just meant the PCM Target Charging Voltage and Generator Duty Cycle might not adjust (properly) without IBS data - i.e. not fall back to some other, pre-IBS, smart charging parameters.

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