Battery Terminals, Sparks flying, educate me !

[pltek]

To disable the aux, I tried isolating the aux batt. neg. cable. I took #1 off, removed the #42 fuse and as I put the other neg terminal back on, sparks. Got into Jeep, dead.

Went back out and before trying with the other neg cable #2,, I disconnected the positive cable and when I put the other black cable back on terminal first, sparks, then put positive back on but this time jeep fired up so I know which one is aux now.

I am sure it has something to do with how the dual batteries are wired and I don’t understand so can someone enlighten me on why are these sparks flying? How could I have prevented this?

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[ShadowsPapa]

To disable the aux, I tried isolating the aux batt. neg. cable. I took #1 off, removed the #42 fuse and as I put the other neg terminal back on, sparks. Got into Jeep, dead.

Went back out and before trying with the other neg cable #2,, I disconnected the positive cable and when I put the other black cable back on terminal first, sparks, then put positive back on but this time jeep fired up so I know which one is aux now.

I am sure it has something to do with how the dual batteries are wired and I don’t understand so can someone enlighten me on why are these sparks flying? How could I have prevented this?

it's normal to have some sparks when reconnecting the negative battery terminal to the ground cable because some systems are alive all, or at least much of the time. If you have the fob with you when working on it, even more systems are "alive". Do this sort of work with the fob in the house.

Of the two black cables attached to the IBS, which is clamped to the top of the negative battery terminal on the main battery, one goes to the aux battery and the other to chassis ground.
One will likely give some sparks (chassis ground, because of the living systems) and the other may not if the battery conditions and voltages are the same.


What was your goal? Just avoid having to replace the aux battery when it goes bad, and replace only the main battery (as it will go dead, too) ?


Which cable is which depends on the year of your Jeep as at some point in 2021 model year, it was changed.

For 2020 and certain early 2021 models, the cable shown on the left is the aux battery ground.
For 2022 and later, the one on the right in this picture is the aux battery ground.

 

[Lost1wing]

it's normal to have some sparks when reconnecting the negative battery terminal to the ground cable because some systems are alive all, or at least much of the time. If you have the fob with you when working on it, even more systems are "alive". Do this sort of work with the fob in the house.

Of the two black cables attached to the IBS, which is clamped to the top of the negative battery terminal on the main battery, one goes to the aux battery and the other to chassis ground.
One will likely give some sparks (chassis ground, because of the living systems) and the other may not if the battery conditions and voltages are the same.


What was your goal? Just avoid having to replace the aux battery when it goes bad, and replace only the main battery (as it will go dead, too) ?


Which cable is which depends on the year of your Jeep as at some point in 2021 model year, it was changed.

For 2020 and certain early 2021 models, the cable shown on the left is the aux battery ground.
For 2022 and later, the one on the right in this picture is the aux battery ground.

I remember reading someone saying that you minimize sparks by leaving the fob away from the vehicle like you said and waiting 30 minutes before removing the negative.

Nice to see you back at it!

 

[ShadowsPapa]

I remember reading someone saying that you minimize sparks by leaving the fob away from the vehicle like you said and waiting 30 minutes before removing the negative.

Nice to see you back at it!

LOL -thanks.
Yes, I didn't add the wait bit, I guess "assuming" (which isn't a great thing) it had been sitting a while anyway - projecting my own habits into it.

As far as the other - mind is sort of willing, the body still resisting.

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