ESS Dual Battery Management

[mazeppa]

By the way the various JLs/JTs battery cables I checked were 2020 and earlier models.

I initially planned to use hardwired dual meter box similar to yours except using a momentary push button DPDT switch to engage both meters at once momentary when the button was pushed using one common/NO terminal set for each of the two meter circuits. I chose a momentary switch to keep from draining the batteries if left on, even though these meters only have a minimal power usage.

https://smile.amazon.com/gp/product/B07FWSZRNX/ref=ppx_yo_dt_b_asin_title_o02_s01?ie=UTF8&psc=1


Later decided to not leave the meter box hardwired and switched to alligator clips test leads, might later use the meter box for other 12 volt DC testing.

Sponsored

 

[Rhinebeck01]

@mazeppa

Real nice, clean set-up there..

------

I prefer the Dual meter with individual manual on/off switches as in the set-up I am running.

I can turn one or both meters on and observe ..... continually observe what is going on lets say. Could not do this with a momentary switch, unless I stood there and constantly pressed the momentary switch. ......Yes, I have to remember to turn off the meter(s).

Also, I want a hardwire set-up and no alligator cables.. a set-up that is in place and I can use on the road, etc., and no having to hook up the set-up. IF I want to test other vehicles, I have a tester for that..

Anyway, I would not change the way Jerry did my set-up... He mentioned having a single meter, but again this is not appealing to me... In closing, I'm a very happy camper with the set-up I have.

 

[Jebiruph]

By the way the various JLs/JTs battery cables I checked were 2020 and earlier models.

I initially planned to use hardwired dual meter box similar to yours except using a momentary push button DPDT switch to engage both meters at once momentary when the button was pushed using one common/NO terminal set for each of the two meter circuits. I chose a momentary switch to keep from draining the batteries if left on, even though these meters only have a minimal power usage.

https://smile.amazon.com/gp/product/B07FWSZRNX/ref=ppx_yo_dt_b_asin_title_o02_s01?ie=UTF8&psc=1


Later decided to not leave the meter box hardwired and switched to alligator clips test leads, might later use the meter box for other 12 volt DC testing.

Do you have a link to the box you are using to mount the meters in?

 

[Gee-pah]

There have been occasional reports of the High Current 150A ESS fuse blowing. The aux battery gets charged by the alternator through this fuse and when it blows, the aux battery will eventual lose it's charge and the internal electronics will go dead along with it. The fuse gets blown when the main battery positive terminal is disconnect from the main battery and makes contact with ground while the aux battery is still connected.

I've been trying to come up with a low cost emergency replacement 150A fused jumper. After an initial order resulted in a very large 150A fuse, I found these reasonably sized 150A fuses. https://www.amazon.com/gp/product/B00W5SGJE6/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1

Here's what the fuse looks like with a 6 AWG cable lug attached by a 10-24 3/8" bolt. This is as far as I've got so far, I'm still working on how to cover the bolts so they don't short out while still maintaining visibility to the fuse and access to the bolts. My current thought is to use shrink tubing, but not shrinking it down over the bolts so it can be peeled back when needed.

Thanks as always Jerry for your information and solution packed posts.

Question: given your claim is that a 150 amp fuse on the high current fuse bar can blow under the conditions you describe, and that there appears, based on this video, to be 2 such fuses within the fuse bar, do you believe it to be fuse 3 or 4 in this video:



I'd also like to add, for those who may not know, that it's my best understanding (Jerry correct this if wrong) that blowing any of these fuses on the high current fuse bar requires replacement of the entire bar: your hack clearly allowing you time between when the 150 amp fuse was blown, and acquiring another fuse bar.

But replacement of the far more expensive entire PDC is not indicated.

(I have no affiliation with this vendor for the fuse bar. It's the first one I found on a search.)

https://www.moparpartsinc.com/p/Jee...MI4rSC45Wc7gIV7PzjBx02PAheEAQYASABEgIRi_D_BwE

 

[mazeppa]

Do you have a link to the box you are using to mount the meters in?

Look for "project box", various types and sizes

https://www.amazon.com/s?k=project+box&ref=nb_sb_noss

 

[mazeppa]

@mazeppa

Real nice, clean set-up there..

------

I prefer the Dual meter with individual manual on/off switches as in the set-up I am running.

I can turn one or both meters on and observe ..... continually observe what is going on lets say. Could not do this with a momentary switch, unless I stood there and constantly pressed the momentary switch. ......Yes, I have to remember to turn off the meter(s).

Also, I want a hardwire set-up and no alligator cables.. a set-up that is in place and I can use on the road, etc., and no having to hook up the set-up. IF I want to test other vehicles, I have a tester for that..

Anyway, I would not change the way Jerry did my set-up... He mentioned having a single meter, but again this is not appealing to me... In closing, I'm a very happy camper with the set-up I have.

Your rationale on why you prefer the individual manual on/off switches is a better choice if you are leaving the meters permanently mounted. I went back and forth on weather to temporary or permanently mount the meter box, If I later redecide to permanently mount I will probably go with some type of manual on/off switch(es).

 

[mazeppa]

Thanks as always Jerry for your information and solution packed posts.

Question: given your claim is that a 150 amp fuse on the high current fuse bar can blow under the conditions you describe, and that there appears, based on this video, to be 2 such fuses within the fuse bar, do you believe it to be fuse 3 or 4 in this video:



I'd also like to add, for those who may not know, that it's my best understanding (Jerry correct this if wrong) that blowing any of these fuses on the high current fuse bar requires replacement of the entire bar: your hack clearly allowing you time between when the 150 amp fuse was blown, and acquiring another fuse bar.

But replacement of the far more expensive entire PDC is not indicated.

(I have no affiliation with this vendor for the fuse bar. It's the first one I found on a search.)

https://www.moparpartsinc.com/p/Jee...MI4rSC45Wc7gIV7PzjBx02PAheEAQYASABEgIRi_D_BwE

Ouch $46, but a lot less expensive than damage possibilities from a shorted out battery.

 

[Jebiruph]

Thanks as always Jerry for your information and solution packed posts.

Question: given your claim is that a 150 amp fuse on the high current fuse bar can blow under the conditions you describe, and that there appears, based on this video, to be 2 such fuses within the fuse bar, do you believe it to be fuse 3 or 4 in this video:



I'd also like to add, for those who may not know, that it's my best understanding (Jerry correct this if wrong) that blowing any of these fuses on the high current fuse bar requires replacement of the entire bar: your hack clearly allowing you time between when the 150 amp fuse was blown, and acquiring another fuse bar.

But replacement of the far more expensive entire PDC is not indicated.

(I have no affiliation with this vendor for the fuse bar. It's the first one I found on a search.)

https://www.moparpartsinc.com/p/Jee...MI4rSC45Wc7gIV7PzjBx02PAheEAQYASABEgIRi_D_BwE

It's the fuse connected to N3.

 

[Jebiruph]

Here's a working single meter. The thing I like about running one meter is that it may be easier to accommodate a single meter inside the cab as opposed two meters. You can also use the in cab power and ground, you only need to run 1 wire under the hood to the aux battery negative cable.

Here's how I tested it. I connected the meter to these two batteries with a jumper cable between the positive terminals of the batteries. The switch has 3 positions, the center position is off. I did notice that one of the batteries may need charged.

 

[Htfan]

Absolutely love this thread!

 

[mazeppa]

I modified one @Jebiruph images to theoretically isolate the aux battery with just one switch and at the same time ensure N1 is always supplied with +12 volts power in respect to the body ground.

On the PCR, the +12 volts low amp PCR control circuit green wire is left alone, the black negative wire is cut and relocated to the isolator switch as shown (also could relocated to the aux battery negative terminal.)

Normal operation: when the aux battery isolator switch is closed (aux/main batteries in parallel), the PCR will function as designed because its black negative wire is common with the body ground as is the aux battery negative terminal.

Aux battery isolated: when the aux battery isolator switch is opened, the PCR's NC contacts now will never open because the low amp control circuit is disabled (opened negative side, no path to body ground.) N1 will be supplied power by the main battery that is connected to N2 through the high current fuse busbar to N3 and through the PCR. As always since the aux battery negative terminal is ISOLATED from the body ground, the aux battery doesn't supply power to any devices.


On another note, I have been wanting to try this since I have the a ESS Dual Battery Management hardware now in place.

What will happen if the aux battery is isolated and N1/N2 are not jumpered together. When there is a call for an ESS event and the PCR opens its NC terminals and then N1 would have 0 volts in respect to body ground. Does every device powered by N1 go dead, or is there a failsafe that immediately terminates the ESS event?

 

[Jebiruph]

What will happen if the aux battery is isolated and N1/N2 are not jumpered together. When there is a call for an ESS event and the PCR opens its NC terminals and then N1 would have 0 volts in respect to body ground. Does every device powered by N1 go dead, or is there a failsafe that immediately terminates the ESS event?

This is why there is a pre start test of the aux battery. If the test fails with 0 volts at N1, ESS is disabled and the start is re-attempted with ESS disabled, no test. If ESS passes the pre start test, but there are 0 volts at N1 when it's engaged, I think you're dead were you sit.

 

[Gee-pah]

I'm lost.

At least in the 3.6L JL, in the scenario where cold crank tests of the ESS battery (i.e. Jerry's "pre start test") are passed, and the driver sits with the brake at, say, a traffic light, aren't numerous tests, from the steering wheel not being turned, to not being in a manual gear (if an automatic), to the engine being warmed up, to not stopping on a hill, in addition to the ESS battery having adequate voltage all necessary before ESS will engage?

And if ESS does engage, isn't loss of enough voltage in the ESS battery during the event a criterion to end the ESS event early?

 

[Jebiruph]

I'm lost.

At least in the 3.6L JL, in the scenario where cold crank tests of the ESS battery (i.e. Jerry's "pre start test") are passed, and the driver sits with the brake at, say, a traffic light, aren't numerous tests, from the steering wheel not being turned, to not being in a manual gear (if an automatic), to the engine being warmed up, to not stopping on a hill, in addition to the ESS battery having adequate voltage all necessary before ESS will engage?

And if ESS does engage, isn't loss of enough voltage in the ESS battery during the event a criterion to end the ESS event early?

How do you know the voltage of the ESS battery without separating the batteries? You can't separate the batteries to see if it's safe to separate the batteries. The pre start test is the only opportunity to test the ESS battery, the rest of the time it's in parallel with the main battery.

 

[Gee-pah]

How do you know the voltage of the ESS battery without separating the batteries? You can't separate the batteries to see if it's safe to separate the batteries. The pre start test is the only opportunity to test the ESS battery, the rest of the time it's in parallel with the main battery.

While I don't know that the ESS battery is for sure tested for voltage prior to an ESS event, why would you think it not possible to separate the batteries for an instant prior to an ESS event so that the ESS battery's voltage could be tested? The alternator and main battery on the 3.6L are clearly more than enough to run any electrical needs while this extremely quick test of the the ESS battery's voltage, as you correctly report required in isolation, is effected (hypothetically or not)?

More recent 3.6L JL's which fail the ESS battery test at crank disable ESS as you describe, and take this battery out of the picture (correct?) for the rest of the trip, and things run fine on the main battery and alternator alone, right?

(Maybe I misunderstand what you are talking about.)

I suppose I could test this. I could attach a battery cutoff switch like you use in your setups Jerry to the negative cable that leads from the ESS battery to the main one--initially when the 3.6L cold cranks, with that circuit closed/intact.

My 3.6L is on a trickle charger when at rest. Getting ESS to kick in once it's warmed up shouldn't be a problem. I could then put the rig in park, get out, open the hood, and use this switch to disconnect the ESS battery from the main one and drive some more, coming to a braked stop.

I hope your wrong about only testing the ESS battery's voltage upon cold crank, but if you're right Jerry, I'd agree. The vehicle should die once the ESS event is attempted to be engaged, shutting off the engine with no alternator, main, or ESS battery to energize appliances off of.

Sponsored