ESS Dual Battery Management

[Rhinebeck01]

This is the Velcro that I used to secure the box and the disconnect switch to the battery cover with. The adhesive on this product really grabs onto / adheres to the material that the JL's battery cover is made of.
https://www.amazon.com/VELCRO-Brand-Industrial-Conditions-Professional/dp/B005P52WPG/ref=sr_1_2?crid=2PIJLUY1DCF0Y&dchild=1&keywords=2x3+velcro&qid=1604411077&sprefix=velcro,+2x3,aps,201&sr=8-2&th=1

And to cover the exposed wires of the kit.... 1/4" black, wire loom split tubing auto wire, conduit flexible covering:

Sponsored

 

[Yellow Cake Kid]

"the status of only one battery is reported to system by the IBS."

???????


Voltage across shunt when one battery is on the circuit.

Voltage across shunt when both batteries are on the circuit.

There are, of course, other measurements being made by the IBS, which are influenced by how the batteries are connected on the circuit.

For example;
voltage measurement of a battery
(note the previous voltage measurements illustrated the methodology for making current measurements, so a load was required. In the following examples, a load is not required but was used as shown. Voltage measurements can be made on an open circuit, and the variance between measurement of one battery and the parallel array will be lessened, but the affect of the second battery will still be apparent. In these examples the batteries are fresh and nearly matched. The difference in measurements will be greater when the batteries are no longer matched in voltage and capacity.)

voltage measurement of a battery when it is placed in parallel array

The IBS may appear to be connected to just one battery, but the affect of the second battery, when it is connected to the circuit, influences the measurements made.

I am optimistically confident that FCA engineers knew this, and suspect they added a "fudge factor" to the OEM dual battery management strategy, regardless of the fact that the OEM dual battery management seems less than effective.

It seems like a good thing that Jeeps are supplied with lead acid chemistry batteries.

The lead acid batteries can withstand a wide variety of conditions, and appear operable for a lot longer than batteries that demand being cared for.

It seems a shame that Jeep shoved a second battery into a system that was ideally suited to a single battery of adequate capacity, while it dismissed the opportunity to provide a system that was ideally suited to the way the Jeep attempts to use two batteries. Maybe next time.

 

[Gee-pah]

It may be possible to do what you suggest, but every cable and component you add creates additional points of failure.

Yeah--having slept on it I've come to realize that with a switched fused jumper between N1 and either N2 or the main battery's positive post....

and a wrench (to configure desired aspects of the negative wires), all configurations are possible for the occasional need to test or configure my batteries in non factory ways to get out of a jam..

Thanks...

 

[Gee-pah]

....I am optimistically confident that FCA engineers knew this, and suspect they added a "fudge factor" to the OEM dual battery management strategy, regardless of the fact that the OEM dual battery management seems less than effective.

It seems like a good thing that Jeeps are supplied with lead acid chemistry batteries.

The lead acid batteries can withstand a wide variety of conditions, and appear operable for a lot longer than batteries that demand being cared for.

It seems a shame that Jeep shoved a second battery into a system that was ideally suited to a single battery of adequate capacity, while it dismissed the opportunity to provide a system that was ideally suited to the way the Jeep attempts to use two batteries. Maybe next time.

I take no issue with your thoughts as it regards battery science--in large part because it appears that your subject area knowledge surpasses mine and likely is correct.

With that said, and I'm not suggesting you disagree or don't already appreciate this, perhaps we need to take ourselves back to what motivated this setup, and that is EPA CAFE standards.

FCA was highly incentivized to incorporate an engine start top system into the ICE JL--particularly a non-latching one, to reap the gas mileage savings such a system could provide when tested by regulators. It was either that or incur extremely large penalties (or buy equally costly carbon credits from the likes of Tesla Inc.) whose cost would be shared with JL owners and lessees.

For those "catching up," a non-latching system requires the operator to expressly turn off the ESS system with each cold crank of the vehicle, without otherwise buying start/stop disabling tech (e.g. Tazer JL). As discussed elsewhere on the forum, non-latching systems get to report greater gas savings to regulators than factory based latching ones that remember their state from one cold crank to another.

Practically speaking, FCA had to create a system that would not strand JL drivers, particularly at a red light in traffic, even if it erred on the side of designing a system that didn't engage because the ESS/Aux battery lacked adequate power.

Without getting into the well hashed politics of this system, many freedom embracing JL owner tend to hate having such systems imposed on them, even if they worked flawlessly (not!), on top of the wear and tear such things impose on the moving parts of a vehicle, despite all the so called heavy duty components of the system.

Couple this with the unusually high power demands of some owners, with accessories like off road gear, and it seemed logical, despite all the battery science efficiency losses of same, to create a system that preserved the cranking battery--enter a 2 battery system.

As it is, FCA screwed up the design in the initial JL release, creating a point of weakness in the computer logic, in requiring the ESS/Aux battery to have adequate charge before cold cranking, despite this battery not being the one bearing most of the cranking demands--fixed in 2019, with dealer flashes for the 2018, and hacks like Jerry's.

Perhaps the engineers lost out to the beans counters and executives when designing the model.

 

[Jebiruph]

"the status of only one battery is reported to system by the IBS."

???????


Voltage across shunt when one battery is on the circuit.

Voltage across shunt when both batteries are on the circuit.

There are, of course, other measurements being made by the IBS, which are influenced by how the batteries are connected on the circuit.

For example;
voltage measurement of a battery
(note the previous voltage measurements illustrated the methodology for making current measurements, so a load was required. In the following examples, a load is not required but was used as shown. Voltage measurements can be made on an open circuit, and the variance between measurement of one battery and the parallel array will be lessened, but the affect of the second battery will still be apparent. In these examples the batteries are fresh and nearly matched. The difference in measurements will be greater when the batteries are no longer matched in voltage and capacity.)

voltage measurement of a battery when it is placed in parallel array

The IBS may appear to be connected to just one battery, but the affect of the second battery, when it is connected to the circuit, influences the measurements made.

I am optimistically confident that FCA engineers knew this, and suspect they added a "fudge factor" to the OEM dual battery management strategy, regardless of the fact that the OEM dual battery management seems less than effective.

It seems like a good thing that Jeeps are supplied with lead acid chemistry batteries.

The lead acid batteries can withstand a wide variety of conditions, and appear operable for a lot longer than batteries that demand being cared for.

It seems a shame that Jeep shoved a second battery into a system that was ideally suited to a single battery of adequate capacity, while it dismissed the opportunity to provide a system that was ideally suited to the way the Jeep attempts to use two batteries. Maybe next time.

In your examples where you measure the voltage across the resistor in series with the battery, regardless of what the voltage is, I can always calculate the the current (V/R=I) discharge out of that battery. If I know the over all capacity of the battery, by keeping track of the accumulated discharge from the battery, I can estimate the remaining capacity of the battery. I can do that without any idea what is happening anywhere else in the circuit.

 

[Rhinebeck01]

 

[Jebiruph]

I'm seeing more posts related to one of the high current fuses getting blown, resulting in the aux battery going dead and stranding the jeep. The fuse is blown when the positive main battery terminal is disconnect from the battery and makes contact with a metal surface. The aux battery is still connected to the main battery positive terminal and shorting it out blows the 150A PCR fuse (N3) that connects the aux battery to the main battery and alternator.

If someone had a mind to, they could easily wire up an LED to indicate a hot main battery positive terminal. I mocked one up, here's what it looks like.

Here's the LED hooked up with both the main battery terminals connected.

Main battery positive terminal disconnected. (This is starting to feel like a magic trick).

Both main battery terminals disconnected, LED is still lit. (this is magic!)

It's not surprising that people are letting the positive short out at this point, nobody is expecting it to still have power. Here's the LED I used. It was less than 20 cents when bought in bulk.

 

[Gee-pah]

I'm seeing more posts related to one of the high current fuses getting blown, resulting in the aux battery going dead and stranding the jeep. The fuse is blown when the positive main battery terminal is disconnect from the battery and makes contact with a metal surface. The aux battery is still connected to the main battery positive terminal and shorting it out blows the 150A PCR fuse (N3) that connects the aux battery to the main battery and alternator.

If someone had a mind to, They could easily wire up an LED to indicate a hot main battery positive terminal. I mocked one up, here's what it looks like.

Here's the LED hooked up with both the main battery terminals connected.

Main battery positive terminal disconnected. (This is starting to feel like a magic trick).

Both main battery terminals disconnected, LED is still lit. (this is magic!)

It's not surprising that people are letting the positive short out at this point, nobody is expecting it to still have power. Here's the LED I used. It was less than 20 cents when bought in bulk.

Thanks for this heads up Jerry.

Part in parcel with this situation is the reminder that only the high amperage fuses on the driver's side of the Power Distribution Center (PDC), the later that black box with the cover on top of the engine bay nearest the front passenger's seat need replacement in these cases--not the entire PDC. Yes, the entire bank of high amp fuses is sold as one piece, so blow any one fuse and you're committed to buying all of them new---but NOT the entire PDC.

I've been thinking about stocking one of these Jerry @Jebiruph . What's your thoughts on this?

 

[Jebiruph]

Thanks for this heads up Jerry.

Part in parcel with this situation is the reminder that only the high amperage fuses on the driver's side of the Power Distribution Center (PDC), the later that black box with the cover on top of the engine bay nearest the front passenger's seat need replacement in these cases--not the entire PDC. Yes, the entire bank of high amp fuses is sold as one piece, so blow any one fuse and you're committed to buying all of them new---but NOT the entire PDC.

I've been thinking about stocking one of these Jerry @Jebiruph . What's your thoughts on this?

The bypass jumper is a temporary fix for when the fuse blows and the aux battery is depleted and cannot power the system electronics. The jumper doesn't replace the 150A fuse, but it allows the main battery to power the system electronics. You should also be able to make a 150A jumper to temporarily replace the blown fuse.

That said, I would not argue with someone that felt it was worth having a spare.

 

[Rhinebeck01]

Pic shows the quick disconnect I fashioned. Unlike the wing nut I had there, the coupler does not hit the wingnut next to it. This quick disconnect is very easy to tighten up and or loosen thanks to the T affair. I also left room above the T, so I could get a 10mm socket on there if I want.

An M6 x 1, 30mm length, stainless steel coupler ($1.67)..... I drilled it and passed an aluminum nail through the hole. Softer material nail, press fit into the hole so it is not movable. Painted with plasti-dip.

 

[OldGuyNewJeep]

Pic shows the quick disconnect I fashioned. Unlike the wing nut I had there, the coupler does not hit the wingnut next to it. This quick disconnect is very easy to tighten up and or loosen thanks to the T affair. I also left room above the T, so I could get a 10mm socket on there if I want.

An M6 x 1, 30mm length, stainless steel coupler ($1.67)..... I drilled it and passed an aluminum nail through the hole. Softer material nail, press fit into the hole so it is not movable. Painted with plasti-dip.

Pretty slick, Bill. Nice job.

 

[Rhinebeck01]

Though my stock JL's, Main battery has done me right over the last 2.5 years, I have decided to retire it and install a NORTHSTAR Pure Lead Automotive Group 48 Battery NSB-AGM48.

The Northstar, will go in this Thursday after Fedex delivers it. Cost me $269.97 total to include shipping.

Trivia: A stock JL's, OEM, Main AGM battery, retails for just over $200.00.

On edit 3/9/21:

Based on recent posts, it seems the 94R will indeed fit a JL that has the tow package..... I had an Odyssey rep, who checked with his supervisor say a 94R would not fit the JL's tray.

Anyway, the JL with the tow package comes with a 700CCA Main. The 48 has 775CCA, which is plenty for our needs...

Sure had I been given accurate info, I would based on price and availability probably have gone with the 94R .... not that I would have really needed the additional 75 CCA.. The 94 is 850 CCA.

Anyway, the Odyssey and Northstar 48's are 75CCA bigger and for sure a more trustworthy battery then the OEM.

-----------------------------------

As I have posted before, I run my 2dr., Rubi 3.6 JL , automatic, with just the Main battery doing the deed lets say..... and with the Aux battery disconnected........the Aux remains, my lets call it backup battery. The Aux is in good health and I do monitor it and maintain it.

MY JL is a daily driver, no add on's needing lots of 12v so, no need of a pricey Offroad Dual Battery system..

I have been doing as mentioned, since around 8/18 and have accumulated just over 27,000 with the bypass jumper in place/in use.. ... ... running with just the Main battery in use and ESS, out of the picture thanks to a SmartStopStart unit. Never any issues... never any EVIC notices..... 8-)



With that said I went with the highly regarded, Made in the USA (Missouri) Norstar Group 48 AGM battery. I am confident this battery and Jerry's ESS Dual Battery Management Kit will really do the deed for me.

 

[Rhinebeck01]

Have been running with Jerry's, ESS Dual Battery Management kit installed on my JL for about a month and a half now.... and about 1,100 miles. Terrific kit!

Yes, I did replace the sotck Main battery with a Northstar NSB-AGM 48 Battery.

Also, I had TSB 18-092-19 applied. (Power Control Update) Though my JL has over 36,000 miles on it, the application of the TSB, was covered under the longer Power Train Warranty.

Here are pics of the current set-up on my JL:

 

[Htfan]

Have been running with Jerry's, ESS Dual Battery Management kit installed on my JL for about a month and a half now.... and about 1,100 miles. Terrific kit!

Yes, I did replace the sotck Main battery with a Northstar NSB-AGM 48 Battery.

Also, I had TSB 18-092-19 applied. (Power Control Update) Though my JL has over 36,000 miles on it, the application of the TSB, was covered under the longer Power Train Warranty.

Here are pics of the current set-up on my JL:

Love this! Thanks for sharing these pictures. Also, next time you replace your main battery you can go larger with higher CCA rating with a group 94 battery. Same tray just remove the plastic piece (shown in your first image below negative side) for the factory size battery.

 

[Htfan]

@Htfan ... I mentioned this a post or two back".....

CAVEAT:
There is a forum thread in which a JL owner states he installed a Larger , Group 94 battery.

After careful measurement and then checking specs on some of the high end batteries that I would even consider purchasing/installing, it became very apparent that based on battery physical measurements, (footprint) there was a very high probability, that I/ you could not squeeze one into a JL's 3.6 battery shelf... you could not squeeze it in and have a safe install, whereby the battery was restrained in some fashion or even squeeze it in, regardless.. Guess you might be able to find a Group 94 battery with a smaller footprint but not one of the highly touted ones that I spec'd out.

With that said I went with the highly regarded, Made in the USA (Missouri) Norstar Group 48 AGM battery. I am confident this battery and Jerry's ESS Dual Battery Management Kit will really do the deed for me.

Great point! It's a must to verify the exact dimensions, terminal orientation etc. of any larger over-spec battery before purchasing.

Sponsored