I fouled up - how bad?? Grounds, starting engine with only AUX batt

[kd1yt]

Seeking input on this especially but not only from ShadowsPapa - but welcome other input also!

I fouled up - the question is how bad and whether or how much damage I may have caused

For background, this mistake is very unlike "usual me". I had COVID, back in the fall, got over the actual COVID infection. _BUT_ the "brain fog" is hanging around for an extended period. This episode is one of the artifacts of the brain fog. I am usually meticulous and careful with anything related to vehicle care, safety, etc. I have done lots of vehicle wiring and electrical work; I've fully-rewired major portions of vehicles.

What happened:

I'm doing some minor to medium audio improvements: new speakers, etc. I've done lots of that kind of work for my own vehicles and other peoples' vehicles, so I thought that this would be well within my zone of current competence, even with the brain fog.

So, first thing,: I did what I have done in any of the vehicle electrical work I have done for 40++ years on many vehicles:

I started by removing the battery ground connection terminal.

I know that my Gladiator has auto-stop-start. I somehow (brain fog) did not have the auto-stop-start in mind as I unhooked the battery ground.

A couple of hour later I remembered the presence of the auto-stop-start. And said to myself "oh yeah, gotta make sure that I specifically unhook the ground connection for the AUX battery from the ground cable. Yeah, I will be sure to do that"

The brain fog I'm struggling with causes issues with working memory and distractability.

So, I hadn't remembered to specifically unhook the AUX battery ground cable from the main battery ground cable. It just slipped my mind.

And, the main ground cable was already unhooked from the main battery's ground post.

Then- a day layer (speaker project paused) I needed to move the vehicle a short distance, because of something else.

As I went to move the vehicle, I forgot that I'd taken the main ground cable off of the main battery ground post.

The vehicle started and moved OK. Was only running a short time - less than a minute.

No fireworks or malfunctions as I moved it.

Several hours later I realized that I had started the vehicle with the main ground cable off of the main battery's ground post terminal.

So the vehicle somehow did start and run with only the AUX battery hooked up, through the connection of the AUX battery's ground at the cable that would go to (but was unhooked from) the main battery ground post.

#1 - this was dumb, I know that

#2 - I am surprised that the vehicle actually started and that it didn't just pop a fuse or fusible link

#3 - I am left really concerned that in starting the vehicle in this way, I pulled way too much current through wiring or contactors/ relays for the AUX-battery (and things fed from the AUX battery's power system).

#4 - if this were a 1950s-2000 vehicle, like most of the ones I have had apart - I would have no problem figuring out both the circuit topography and physical topography of the wiring. And I would look for signs of overheated insulation from too much current, etc. But there is so much fit into so little space in the wiring of my Gladiator, and I am not familiar with the physical layout of the Auto-Stop-Start's components and cabling, that I don't really have a sense of where to even check. Also: the brain fog is not helping. The sense of what a foul-up this was is not helping.

#5 If I caused damage or risked causing damage, I want to correct it so that I don't have some lurking damage that is going to fail at some unexpected time.

I GREATLY appreciate any help that anyone can offer to give me a sense of whether I could have caused damage, or what could have been damaged, what to look for, and how to correct/protect from any "fallout" from this.

Thanks very much in advance

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[Kevin_D]

Personally, I wouldn't worry about it.
I've started mine on the aux. battery (mostly out of curiosity,) and it started and ran fine, with no adverse effects. The fact that it started did kind of surprise me, though.
Now, the Jeep had been running & was warmed up, and it was a reasonably warm day.

Kevin

 

[Radio Guy]

Looking over the truck wiring diagram it appears current would have to flow from the AUX battery through the PCR then high current fuse 3 to the starter. This brings up questions I can't answer at the moment like does the PCR normally connect the AUX battery in parallel with the main battery during starting? That is the only way you could have started the truck with only the AUX battery connected.

With only the AUX battery connected that would pull full cranking current through the PCR and high current fuse 3, which is apparently large enough to handle the cranking current in your case. In my opinion the only thing that may have been affected are the contacts on the PCR, but it may be designed to handle full cranking current anyway.

Does anyone know if the AUX battery is switched in parallel with the main battery via the PCR during cranking?

 

[Kevin_D]

Does anyone know if the AUX battery is switched in parallel with the main battery via the PCR during cranking?

My initial thought would be, "Yes, it is," as the only time the two batteries are isolated is during an ESS event.

Kevin

 

[ShadowsPapa]

does the PCR normally connect the AUX battery in parallel with the main battery during starting? That is the only way you could have started the truck with only the AUX battery connected

Yes. They are parallel except for a brief test when the PCR opens. I've not checked to see exactly when that happens, it's likely just before the cranking begins. Note that when you press that button the starter doesn't begin spinning instantly.

Seeking input on this especially but not only from ShadowsPapa - but welcome other input also!

I fouled up - the question is how bad and whether or how much damage I may have caused

For background, this mistake is very unlike "usual me". I had COVID, back in the fall, got over the actual COVID infection. _BUT_ the "brain fog" is hanging around for an extended period. This episode is one of the artifacts of the brain fog. I am usually meticulous and careful with anything related to vehicle care, safety, etc. I have done lots of vehicle wiring and electrical work; I've fully-rewired major portions of vehicles.

What happened:

I'm doing some minor to medium audio improvements: new speakers, etc. I've done lots of that kind of work for my own vehicles and other peoples' vehicles, so I thought that this would be well within my zone of current competence, even with the brain fog.

So, first thing,: I did what I have done in any of the vehicle electrical work I have done for 40++ years on many vehicles:

I started by removing the battery ground connection terminal.

I know that my Gladiator has auto-stop-start. I somehow (brain fog) did not have the auto-stop-start in mind as I unhooked the battery ground.

A couple of hour later I remembered the presence of the auto-stop-start. And said to myself "oh yeah, gotta make sure that I specifically unhook the ground connection for the AUX battery from the ground cable. Yeah, I will be sure to do that"

The brain fog I'm struggling with causes issues with working memory and distractability.

So, I hadn't remembered to specifically unhook the AUX battery ground cable from the main battery ground cable. It just slipped my mind.

And, the main ground cable was already unhooked from the main battery's ground post.

Then- a day layer (speaker project paused) I needed to move the vehicle a short distance, because of something else.

As I went to move the vehicle, I forgot that I'd taken the main ground cable off of the main battery ground post.

The vehicle started and moved OK. Was only running a short time - less than a minute.

No fireworks or malfunctions as I moved it.

Several hours later I realized that I had started the vehicle with the main ground cable off of the main battery's ground post terminal.

So the vehicle somehow did start and run with only the AUX battery hooked up, through the connection of the AUX battery's ground at the cable that would go to (but was unhooked from) the main battery ground post.

#1 - this was dumb, I know that

#2 - I am surprised that the vehicle actually started and that it didn't just pop a fuse or fusible link

#3 - I am left really concerned that in starting the vehicle in this way, I pulled way too much current through wiring or contactors/ relays for the AUX-battery (and things fed from the AUX battery's power system).

#4 - if this were a 1950s-2000 vehicle, like most of the ones I have had apart - I would have no problem figuring out both the circuit topography and physical topography of the wiring. And I would look for signs of overheated insulation from too much current, etc. But there is so much fit into so little space in the wiring of my Gladiator, and I am not familiar with the physical layout of the Auto-Stop-Start's components and cabling, that I don't really have a sense of where to even check. Also: the brain fog is not helping. The sense of what a foul-up this was is not helping.

#5 If I caused damage or risked causing damage, I want to correct it so that I don't have some lurking damage that is going to fail at some unexpected time.

I GREATLY appreciate any help that anyone can offer to give me a sense of whether I could have caused damage, or what could have been damaged, what to look for, and how to correct/protect from any "fallout" from this.

Thanks very much in advance

Don't sweat it.

These starters are not like the starters of 30 years. They are pretty low current draw and you just proved it as that N3 fuse is 150 amps. So the starter draws a lot less than that.
The worst case would be having blown that fuse. Unlikely if the truck starts like they normally do - easily.

 

[kd1yt]

Thank you - all- very much!

I was concerned,. at minimum, that I'd have put a lot of strain on wiring (if the AUX battery conductors had not been sized to supply cranking current) and the PCR contacts "backfeeding" starting current in that direction. But from what I think I am seeing now that I am looking at some of Jebiriph's discussions of ESS on here and in the JL forums, it looks as if there are some conditions (like weak main battery) in which the AUX battery may in fact supply cranking power.

My formative vehicle electrical experience was on vintage medium duty truck and classic all-iron stuff that drew and needed massive current to start.

If nothing else, this has been an interesting inspiration to start learning more about the ESS.

I am going to go ahead and replace the AUX battery, was planning on that even before this "excitement" just because the vehicle is now 3.5 years old and I am going to be opening things up in that neighborhood to route some of the audio wiring. This whole project is moving more slowly (to extremes) than I would ever expect due to the "fog"... but at least it is moving.

Again, many thanks!

 

[Radio Guy]

Thank you - all- very much!

I was concerned,. at minimum, that I'd have put a lot of strain on wiring (if the AUX battery conductors had not been sized to supply cranking current) and the PCR contacts "backfeeding" starting current in that direction. But from what I think I am seeing now that I am looking at some of Jebiriph's discussions of ESS on here and in the JL forums, it looks as if there are some conditions (like weak main battery) in which the AUX battery may in fact supply cranking power.

My formative vehicle electrical experience was on vintage medium duty truck and classic all-iron stuff that drew and needed massive current to start.

If nothing else, this has been an interesting inspiration to start learning more about the ESS.

I am going to go ahead and replace the AUX battery, was planning on that even before this "excitement" just because the vehicle is now 3.5 years old and I am going to be opening things up in that neighborhood to route some of the audio wiring. This whole project is moving more slowly (to extremes) than I would ever expect due to the "fog"... but at least it is moving.

Again, many thanks!

Since both batteries are in parallel most of the time, if one battery needs replacing I think its best to replace both.

 

[ShadowsPapa]

Since both batteries are in parallel most of the time, if one battery needs replacing I think its best to replace both.

I tend to agree. These seem to have a typical life of roughly 3 years - at least among many forum members. And they do run in parallel 99% of the time.

I would buy new batteries, charge each of them properly, make sure the IBS was disconnected for 10-15 minutes, then put it all together so the IBS is reset and ready to work on new fully charged battery(s).

 

[kd1yt]

I haven't had signs of failure or trouble from either the main or AUX battery. But I will be peeling into things right around the AUX battery to get to the passenger side firewall grommet to run 12+V for some audio wiring. So I would kick myself if I didn't replace the AUX battery, while I am "in this deep" and then had to pull it all apart all over again soon to replace the AUX battery in the coming months. Especially since I just pressed the "old" AUX battery into starting duty... I do plan to preventatively replace the main battery in the very near future but I prefer (if I can help it) not to have to eat the cost of both batteries in one single serving. I'll put both the new AUX and the existing main batteries on a charger before I put them back in service when I am buttoning things back up on the current effort.

Thank you all, again, very much for your knowledge and suggestions!

 

[IanNubbit]

Without read word for word on replies... You are fine. Theres fuses in place, if anything was "overloaded" it would have just blown a fuse. The only real concern would have been arc from the free dangling ground cable, which obviopulsy it didnt. Don't sweat it and keep rocking.

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