Jumperless aux battery/PCR bypass

[Mr._Bill]

Couldn’t you just disconnect the aux (+) up top and tape that off and be just fine to leave the ground alone?? If the aux is proving to be that parasitic draw on the main, would undoing the (+) aux but leaving the (-) attached be the same as removing the aux (-)?

The Aux Battery is not going to be a parasitic draw on the Main Battery until it starts to fail. At that point, both batteries usually need replaced. The parasitic draw is on both batteries and comes from the computers and other components that never turn off.

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[ShadowsPapa]

Couldn’t you just disconnect the aux (+) up top and tape that off and be just fine to leave the ground alone?? If the aux is proving to be that parasitic draw on the main, would undoing the (+) aux but leaving the (-) attached be the same as removing the aux (-)?

There's no parasitic draw from a battery that isn't failed or failing.
There's so much bad and wrong info out there it's scary.

There's no "proving to be" except in the minds of people who don't know automotive electric systems and batteries.
The issue is coming from people who try things and it happens to appear better to them, they need an explanation and then the next guy copies and pastes it to another place and so on, and it becomes fact.
The aux battery charges from the same source as the crank battery - if the crank battery sees 14.6 volts coming at it, so does the aux battery. And with the smaller battery, that 14.6 would actually charge it faster.

 

[ShadowsPapa]

Me - I'm leaving it alone as there's little chance of a problem in all reality. It's a "makes me feel good" thing for others who are "annoyed" by something.
This isn't a "it's GOING TO HAPPEN to you" sort of thing.
Issues are amplified by the fact that anyone can make a video and post it.

 

[Maximus Gladius]

The parasitic draw is on both batteries and comes from the computers and other components that never turn off.

Hence the need for a tender to be installed and periodic recharging when back at home. I’ve done this and like to keep it charged up at least twice a week. In all my years of driving since the 80’s, I’ve never had to tender my batteries nor be so concerned of draw on the batteries like I’m seeing with this. My Jeep charging system always displays mostly at 14v+ as I’m cruising around but it seems never enough to keep the batteries above 50-70%??

Being self employed in Calgary, I drive over 100 kms per day and turn off the ESS. Why can’t the constant 12.7-14v+ keep these batteries topped up?

 

[Maximus Gladius]

I do see quite a draw on my main battery. If at night, I tender up the main (and aux) so I see 12.7-13.4v in the morning, by the time I get back home the main is reading 12.5. If I leave it and not tender it through the night again, by morning it’s reading 12.4 or less. The tender isn’t telling me I have a faulty battery and the dealership had it hooked up to their system and said all is good but this to me doesn’t seem right and I don’t trust that with the draw im seeing, that there’s nothing to worry about.

 

[Maximus Gladius]

There's so much bad and wrong info out there it's scary.

When I had to tow my truck home last winter, the dealership let the batteries die under their care and the temps were in the -30c range and they told me to fix when I got it home and wouldn’t turn over.

I did lots of reading on here and looked up YouTube vids on the AGM batteries and the info that was constant was “if the AGM voltage drops below a certain v, the battery is done, dead, that’s it it’s damaged, there’s no bringing it back.”

We’ve all read it and heard it. So, not only were my AGM batteries dead and frozen but I’m still using them and can charge them up ,…they just don’t hold the charge and my tender nor the dealership charge system says that anything is wrong.

 

[ShadowsPapa]

I did lots of reading on here and looked up YouTube vids on the AGM batteries and the info that was constant was “if the AGM voltage drops below a certain v, the battery is done, dead, that’s it it’s damaged, there’s no bringing it back.”

We’ve all read it and heard it. So, not only were my AGM batteries dead and frozen but I’m still using them and can charge them up ,…they just don’t hold the charge and my tender nor the dealership charge system says that anything is wrong.

It should read "high risk" or "likely" because there's no guarantee that x will result in Y with an otherwise healthy battery.
I've brought batteries "back from the dead" many times - but in some cases, they won't crank over a V8 engine, but are useful on my test bench for 5 or 6 years after their 5 year warranty.
And some tenders can actually desulfate batteries. I've got 4 different "chargers". One will simply charge - if the battery is old, or has been sitting discharged for a period, it can't do anything. Bring in my Battery Minder and hook it up - and it's a measly 1000 mA device - and after a couple of days that battery acts like nothing ever went wrong. In fact, one such battery is in my Javelin - 7 years old, still cranks the built 360 sitting in it.
I'd got another "Craftsman" battery tender, a 1500 mA device that will also detect faults and attempt "repair" and it does a decent job. Ran it on the battery in my lawn tractor that sat a long time this past summer due to drought. It brought it back to life (that battery is the original - 7 years+ in age)
And then the higher-end 20 amp charger......... it also "detects faults" and seems to do a decent job at that.
But if people - the sort that generally look for information on batteries, like my neighbor - have batteries like yours, they are likely to see that info "battery is toast, recycle it" and believe it because his 30 year old charger can only charge batteries and nothing else.
I figure, at least for me, it's always worth a shot at rejuvenating a battery unless it's really old or shows other signs. I would not put such a battery in my wife's vehicles........ but for me, powers of observation and understanding what is seen will tell me if I need to cut my losses or keep a jump pack handy.

Part of the thing about the online information is that some just bluntly say "it's going to be bad" while others give some technical info on what's going on, and your odds. And even some battery vendors - the big guys out there, disagree on AGM batteries! Seriously - they guys sell them and can't agree........... so what's a consumer to do when the web sites selling batteries have info that's a pot of mixed messages?
Even the SoC (State of Charge) charts vary. But that makes sense because that can vary with the battery itself, its age and history. Some charts are for new batteries with certain AGM technology and others are more for "typical use" situations.
One thing most seem to agree on is that once you cycle a battery down below roughly 12.2 volts or so, long enough and often enough, you cut it's life - it has fewer cycles left. Doesn't mean it's toast, just that you've shortened its life expectancy.

 

[ShadowsPapa]

Hence the need for a tender to be installed and periodic recharging when back at home. I’ve done this and like to keep it charged up at least twice a week. In all my years of driving since the 80’s, I’ve never had to tender my batteries nor be so concerned of draw on the batteries like I’m seeing with this. My Jeep charging system always displays mostly at 14v+ as I’m cruising around but it seems never enough to keep the batteries above 50-70%??

Being self employed in Calgary, I drive over 100 kms per day and turn off the ESS. Why can’t the constant 12.7-14v+ keep these batteries topped up?

A couple of things to note -
When you use any type of charger on a wet battery, there is most likely a "surface charge" at the end. So if you see 13.0 volts or more after charging, it's "likely" that's where the extra above 12.7-12.8 volts is coming from. Hard to say for a fact as some AGM battery makers claim an at rest, 100% SoC voltage of 12.9 or so - I've seen one say "13.0 volts fully charged". Reality? Or were they seeing the surface charge?
My GM factory classes told me (and it's in all the books I have) that you should charge, then drain the surface charge off before doing any further measurements or testing. Back before the advent of LED lighting, the "suggestion" was to turn on headlights for 30 seconds, then wait a minute for voltage to bounce back and that was your fully charged voltage. Then if it was under 12.6 for legacy wet batteries, you had a problem. The issue was people were charging for over-night or a day, then turning off the charger, seeing 12.6 volts or more and assuming all was well. Well, they'd turn on some accessory or try to start it and it was too low to do anything.
So GM and other battery makers said drain off the surface charge before continuing.
For one thing, if the battery won't take and hold a charge, why even bother getting out the test equipment and throwing a load on it? You're done right there.
(*I still have the big stuff from the last century with the big black knob for a carbon pile and fat cables, etc. to test batteries and charging systems although my JT alternator would likely fry this thing)

On batteries not being fully charged.......
We often start with batteries at only 50% at best to begin with (not everyone - many here drive daily and long enough drives). The parasitic load of the truck draws the batteries down when sitting. We drive short drives, maybe every 2 or 3 days. It's contrary to how AGM batteries are supposed to act. All I've seen for years says they charge faster. I could argue that point, I guess.
Add to it cold weather- any battery resists a charge when cold. That's why old systems had temperature compensation built into the voltage regulators. These do, too..... my truck has been hanging at 14.9-15.0 volts for weeks while it's been below 30 degrees. Saturday it got to 40 and the voltage every trip was 14.5. (one reading in JSCAN said the IBS said the temperature was 60 where it was - duh, engine warmth)
There's resistance of the IBS itself - and I can't recall the exact number they use but I figured 2 ohms. At 14.5 volts on the cluster, going through a 2 ohm IBS, you have a current of only 7 amps.
It can take my charger, at 10 amps, 3 or 4 hours to charge a battery sitting at 12.4 volts.
Add the cold and resistance of the battery, you really aren't pushing that much into the battery when you can only pass 7 amps at 14.5 volts through a 2 ohm device.
Some documents say the IBS is 1 ohm. At 15.0 volts that's still only 15 amps..
Not a fast charge especially with a cold battery.
There is resistance of the battery itself, of course.
But pushing higher voltage is problematic as well....... some of these say "max 14.4 volts" right on the battery.

 

[Maximus Gladius]

So just clearing up any miss info that may be expressed here like ‘pull the f42 fuse to eliminate the start/stop ESS’, I did that last night and I’m out driving around today and guess what happened at a stop light?!

If you guessed the engine shut off, you’d be right.

 

[ShadowsPapa]

So just clearing up any miss info that may be expressed here like ‘pull the f42 fuse to eliminate the start/stop ESS’, I did that last night and I’m out driving around today and guess what happened at a stop light?!

If you guessed the engine shut off, you’d be right.

That only prevents the system from opening the PCR to check the aux battery.

Disconnecting the aux battery kicks an error because when you start the truck and the PCR opens to check aux battery voltage, if finds nothing.

All you are doing is being able to disconnect the aux battery, it doesn't really do anything else to ESS.
ESS should still function, just without the aux battery.
On the other hand - you are pulling everything from the crank battery then.

Frankly, there's no real point to it unless you have a bad aux battery and KNOW it's bad, and it's not really the crank battery that's bad.
Like Jerry says - that aux battery gets blamed for a lot of stuff (usually not rightly so) and some want to disconnect it but then they get an error. So pulling that fuse only prevents the error.
It's not a fix for anything - it's a feel good thing, or to cover a REAL problem with the aux battery.

I see it as a possible useful test - in the future if I ever "Suspect" a battery problem, I could pull the ground for the aux battery, pull that fuse, drive the truck and see how things go. If all is well, then the aux battery is suspect. IF there's still issues, it sure wasn't the aux battery.

 

[jebiruph]

I’ve read lots of explanations on ‘how to’ do this but no photos showing the 13mm on top of the 10mm post (IBM).

Maybe this wil help https://www.jlwranglerforums.com/forum/threads/ess-battery-cable-change.86624/post-1806411

 

[ShadowsPapa]

There's so many ways to get around that cable attaching thing - it's being over-thought, IMO.
Under the protective coating, likely zinc or tin/zinc, etc. - what's the core metal of those cable ends?

Get a piece of copper tube, flatten it, harden it, drill it.
It could be tin/zinc plated to make it pretty.
Or get a small copper bar, or even aluminum.
Copper, aluminum, brass and zinc are the most conductive common metals. (note I said common metals - for those who will pick on that LOL)

 

[Maximus Gladius]

Maybe this wil help https://www.jlwranglerforums.com/forum/threads/ess-battery-cable-change.86624/post-1806411

Thanks! This I wanted to see the 13mm on the 10mm post

 

[ShadowsPapa]

Thanks! This I wanted to see the 13mm on the 10mm post

6mm is the stud size............... the smaller one I believe is 5mm so if searching for an adapter or nuts or whatever........ look for the stud size.

I could always make something out of pure zinc.

Be aware when talking of conductivity of things - they are talking pure metals. Alloys throw numbers out the window. The standard for conductivity is pure copper. things are compared to that. Copper alloys go down the tubes in conductivity.

 

[jebiruph]

The electrical studs are either M8 1.25 or M6 1.0.

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