Jumperless Aux Battery Bypass

[JLRik]

Thanks for this!

Sponsored

 

[jingle]

I recently did the jumperless Aux battery delete on my 2020 JL. Everything went fine and I don't have any errors or dash lights. However, if I forget to disable auto start/stop and I'm listening to music (either built in XM or Apple CarPlay), when the car starts from an auto stop, there's a noticeable noise through the sound system - like a record scratch/skip sound. It's a quick "skt" kind of sound - and does it almost every time during an auto start after doing the jumperless aux battery delete.

Anyone else running into this?

I do plan on getting a Tazer or something to permanently turn off the auto start/stop - but in the meantime the noise is concerning.

 

[Mguy]

when the car starts from an auto stop, there's a noticeable noise through the sound system

This has been reported on this board before, and there is some mention here that this is the root cause of the aux battery addition and design. Apparently, the ESS start with your main battery alone results in a voltage drop that the radio/sound system can't handle. Before worrying too much, consider that while voltage upward spikes are known to damage electronics, I'm not aware of similar reports, anywhere, for brief voltage drops (motorized devices are a different situation).

I don't have this issue when I test my ESS system. My main battery is fully charged and in good shape when I do the test. I suggest you do an at rest open circuit test on yours with an external voltmeter. If you see 12.6 or above, test the radio with ESS. If you see below 12.6 with the battery resting for a few days, the battery is the problem and it would be a good time to replace it.

 

[jingle]

This has been reported on this board before, and there is some mention here that this is the root cause of the aux battery addition and design. Apparently, the ESS start with your main battery alone results in a voltage drop that the radio/sound system can't handle. Before worrying too much, consider that while voltage upward spikes are known to damage electronics, I'm not aware of similar reports, anywhere, for brief voltage drops (motorized devices are a different situation).

I don't have this issue when I test my ESS system. My main battery is fully charged and in good shape when I do the test. I suggest you do an at rest open circuit test on yours with an external voltmeter. If you see 12.6 or above, test the radio with ESS. If you see below 12.6 with the battery resting for a few days, the battery is the problem and it would be a good time to replace it.

Thanks, for the reply. I'll try your suggestion around the test and possibly look into a battery replacement.

 

[AndySpill]

This has been reported on this board before, and there is some mention here that this is the root cause of the aux battery addition and design. Apparently, the ESS start with your main battery alone results in a voltage drop that the radio/sound system can't handle. Before worrying too much, consider that while voltage upward spikes are known to damage electronics, I'm not aware of similar reports, anywhere, for brief voltage drops (motorized devices are a different situation).

I don't have this issue when I test my ESS system. My main battery is fully charged and in good shape when I do the test. I suggest you do an at rest open circuit test on yours with an external voltmeter. If you see 12.6 or above, test the radio with ESS. If you see below 12.6 with the battery resting for a few days, the battery is the problem and it would be a good time to replace it.

I definitely like this advice here Mike but am curious about the following:

Presumably that Aux battery had ample voltage when the engine cold cranked to allow ESS events to occur minutes later when all the other conditions for an ESS event to engage (including a warmed up engine) were not only met, but the conditions for exclusion (and as you probably know there are a decent number of these) were not met.

Perhaps, somehow, that Aux battery passes pre engine cold crank voltage tests but might fail load tests: i.e. the whole reason the latter is the gold standard of battery testing over the latter. To rephrase, even though a voltage test may be passed at cold crank, once that Aux battery has to actual deliver electrical current perhaps it tends to "pass out" quickly.

@jingle James: do you find this problem with the radio that you report consistent with ESS events
that are early terminated by the vehicle? Do you have a significant number of early terminated ESS events (one the vehicle ended before you did something to end it like take your foot off the brake?) Do you run a fair share of electrical current drawing (aftermarket) appliances, perhaps above stock, like an aftermarket energy hungry sound system, or lights?

 

[jingle]

@jingle James: do you find this problem with the radio that you report consistent with ESS events
that are early terminated by the vehicle? Do you have a significant number of early terminated ESS events (one the vehicle ended before you did something to end it like take your foot off the brake?) Do you run a fair share of electrical current drawing (aftermarket) appliances, perhaps above stock, like an aftermarket energy hungry sound system, or lights?

Yes - I do only notice it with ESS events. My JL is basically stock -JLRU - Has the 8" factory Alpine system - but no other modifications other than the aux bypass. When I notice the problem/event, it's mainly when I let off the brake and the vehicle early terminates the ESS. I've noticed it during the day (only running lights on with stereo and AC running) and at night. I don't know if it does it EVERY time the ESS is terminated - but when I hear it - it reminds me to disable the ESS via the button. I'll try it today and see if I can get it to do it more than once in a driving scenario.

 

[AndySpill]

Yes - I do only notice it with ESS events. My JL is basically stock -JLRU - Has the 8" factory Alpine system - but no other modifications other than the aux bypass. When I notice the problem/event, it's mainly when I let off the brake and the vehicle early terminates the ESS. I've noticed it during the day (only running lights on with stereo and AC running) and at night. I don't know if it does it EVERY time the ESS is terminated - but when I hear it - it reminds me to disable the ESS via the button. I'll try it today and see if I can get it to do it more than once in a driving scenario.

James:

I'm sorry I didn't realize this when I just posted.

You are running ESS events with just the main battery, right?

If so, and if low voltage is causing your problem, as I see it, you have two options. Reverse your Aux battery pull, including cable and fuse, and put a new Aux battery in your JL (and probably a new main as well as they're replaced in pairs), or don't run ESS events on just the main battery.

As @Mguy Mike astutely pointed out, there's talk that off all the reasons that second battery made it into dual AGM battery JLs it wasn't (the seeming logical reason) for running all those energy hungry aftermarket appliances during an ESS event, sparing the main battery for the post ESS event engine crank, so much as to rather minimize voltage drops to the radio as the main battery handles the post ESS event engine crank, the alternator kicks in, and the two batteries are once again brought into a parallel electrical connection once the engine is running.

I suppose you could replace your main battery, but if you want to run ESS events, do model your dual AGM battery JL's electrical schematic as per factory, IMHO.

 

[jingle]

James:

You are running ESS events with just the main battery, right?

Correct - I did the jumperless aux battery bypass. I only have the ESS events when I forget to use the button to disable the ESS. I had read were it was deemed okay to have ESS on with just the main battery - but it is not my intent to run that way forever. I would either replace the aux battery (undo the bypass) or get a tazer to turn off ESS.

It's just that when I forgot to turn off ESS while only running on the main battery - that I heard the noise through the sound system and worried that it could cause further electrical damage to the Jeep.

 

[AndySpill]

Correct - I did the jumperless aux battery bypass. I only have the ESS events when I forget to use the button to disable the ESS. I had read were it was deemed okay to have ESS on with just the main battery - but it is not my intent to run that way forever. I would either replace the aux battery (undo the bypass) or get a tazer to turn off ESS.

It's just that when I forgot to turn off ESS while only running on the main battery - that I heard the noise through the sound system and worried that it could cause further electrical damage to the Jeep.

I think we agree sir to "file this one away" in the "solved problems" bucket. I say this because your issue manifests when running your factory dual AGM battery JL with one battery while running ESS events, and you appreciate that the matter is resolved, at entire your choice and discretion (and our respect) by turning off ESS when running one battery or ESS on when reverting the battery and fuse disconnection if and when you see fit.

Happy trails.

 

[jingle]

I think we agree sir to "file this one away" in the "solved problems" bucket. I say this because your issue manifests when running your factory dual AGM battery JL with one battery while running ESS events, and you appreciate that the matter is resolved, at entire your choice and discretion (and our respect) by turning off ESS when running one battery or ESS on when reverting the battery and fuse disconnection if and when you see fit.

Happy trails.

Ha - yeah. I can agree with that. Just out of curiosity and for others that run into this - I went out today and intentionally left ESS on.

Driving - Voltage was averaging 14.1-14.2
First stop after engine is warm - ESS kicks in. Voltage drops instantly to 13.6. Then it slowly drops till it hit 12.3. Green light - let off brake - noise through sound system.
Next stoplight - same experience - same noise through sound system.
Turned off ESS - enjoyed the rest of the trip.

So - my recommendation to anyone looking to do the jumperless aux battery delete - is to combine that with a Tazer or other method of disabling the ESS so you don't have to remember to do so.

 

[garyji]

James, What are you running for a main Battery? High end AGM? That's a lot of drop.

G.

 

[Mguy]

My JL is basically stock -JLRU - Has the 8" factory Alpine system - but no other modifications other than the aux bypass.

Well, your sound system could be part of the problem. I don't have a lot of experience with DC amplifiers and subwoofers, but I did have a small setup (not on the Jeep), with a subwoofer, that drew 15 amps at high volume, down to about 5 amps when nearly off. A much bigger system (which I believe is yours), that draws much more amps, could be more sensitive to voltage drops.

If you have the inclination to look deeper into this, adjust your sound settings to minimize power consumption. Balance/fade to smallest speakers and least subwoofer, turn down tone and volume controls. Overall volume just enough to hear the noise if its there. Do a few ESS stop/starts and let us know what happens.

Just for comparison, my JL is a stock 7" display with no subwoofer, usually on low volume, and of course, produces no noise during ESS starts on the main battery alone.

 

[jingle]

James, What are you running for a main Battery? High end AGM? That's a lot of drop.

G.

Mopar/OEM Battery. It's original to the vehicle so it needs to be replaced anyway.

 

[jingle]

Well, your sound system could be part of the problem. I don't have a lot of experience with DC amplifiers and subwoofers, but I did have a small setup (not on the Jeep), with a subwoofer, that drew 15 amps at high volume, down to about 5 amps when nearly off. A much bigger system (which I believe is yours), that draws much more amps, could be more sensitive to voltage drops.

If you have the inclination to look deeper into this, adjust your sound settings to minimize power consumption. Balance/fade to smallest speakers and least subwoofer, turn down tone and volume controls. Overall volume just enough to hear the noise if its there. Do a few ESS stop/starts and let us know what happens.

Just for comparison, my JL is a stock 7" display with no subwoofer, usually on low volume, and of course, produces no noise during ESS starts on the main battery alone.

Interesting thought. I may play with that some and see if I can get an ESS start to not create the noise through the speakers. I'll report back.

 

[AndySpill]

Even if some workaround of stereo system settings could resolve this, I can't help but think that the more pressing issue is the possible, albeit unlikely perfect storm of events that leaves you stranded at a traffic light, unable to warm crank. Such events might include one too many appliances running during that ESS event, a main battery on its way out, a long traffic light, and perhaps a cold night. Reason five, according to Murphy's Law might be a wife in labor.

Sure, your rig is going to test what it thinks is the Aux battery at cold crank, (but is really, due to your Fuse 42 pull the main battery,) and not allow ESS to engage if that battery's voltage is too low, and sure, the vehicle is going to early terminate an ESS event if what it things is the Aux battery, but is really your main battery's voltage drops too low, but in theory, this early termination could happen just as that main battery's voltage drops below the necessary threshold to warm crank the engine.

Under the factory setup, if the vehicle early terminates the ESS event due to the ESS battery voltage dropping too low, the untouched during the ESS event main battery is there to effect the warm crank, and won't be brought back into parallel with the drained Aux battery until the alternator is running, charging them both.

Voltage is but one test of a battery's power and not the gold standard for the fact that voltage could drop like a rock if the (main) battery's ability to deliver electrical current is, as a load test would pick up, compromised.

There is a way to have the vehicle turn ESS off for you in your 2020. Reinsert Fuse 42. Attempt to crank. Expect it to fail as no ESS battery is found. Try again. If the main battery has ample power the crank happens and the dash (EVIC) turns on the ESS off light. Cranking from this point on should happen on the first try, and that light is going to stay on until an energized Aux battery is detected, or the vehicle thinks it is detected (i.e. Fuse 42 is yanked and the vehicle doesn't realize that it's testing the main battery at cold crank, thinking that it's the Aux battery).

(Don't try this on early 2018s, without TSB 18-092-19. They won't crank on second attempt either.)

If you don't mind idiot lights in the dash this saves money on tech to push the ESS button for you but it turns a light on the dash--something many people hate--and risks this light not being able to be turned on by the vehicle to reflect problems that can be masked when the light is always illuminated.

Sponsored