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Replacing Stock Battery(and Bypassing the Aux Battery) Easiest Solution

azjl#3

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Read the thread, from the beginning. Disconnecting the fuse and aux battery wire is too easy not to do it.
I read the thread, not interested in bypassing stock. My question was not how to defeat, it's how the aux battery isolates.

Found it here: essentially aux uses a relay power control to charge and discharge into starter. It is isolated even though it looks like it is not.

https://www.jlwranglerforums.com/forum/threads/aux-battery-wiring-diagram.7438/
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DaltonGang

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just a dumb question i'm sure.... but has anyone attempted or is using a dual battery tray and the ESS system with 2 full size identical batteries? would there be a benefit?
It would be overkill. But if you like to show everyone you have two big batteries then it could be done. The very expensive Genesis Battery System uses two full sized batteries.
An H7 850 CCA AGM battery will start your jeep just as well as two 850 CCA batteries, at half the cost, and zero headache setting it up, bypassing the Aux Battery. Most full sized trucks use 850 or so CCA batteries, and they do just fine.
 

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i was just wondering as for added accessory power and back up power mostly...
 

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It would be overkill. But if you like to show everyone you have two big batteries then it could be done. The very expensive Genesis Battery System uses two full sized batteries.
An H7 850 CCA AGM battery will start your jeep just as well as two 850 CCA batteries, at half the cost, and zero headache setting it up, bypassing the Aux Battery. Most full sized trucks use 850 or so CCA batteries, and they do just fine.
Agreed. Disable ESS and replace primary battery with a better one near the end of it's life.

i was just wondering as for added accessory power and back up power mostly...
You're better off getting a Lithium battery isolator and a LiFePO4 Deep Cycle Battery. Twice the power, half the weight. What's back up power?
 

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I do it by hooking the positive to the main positive battery terminal (since I have not unhooked that from the aux) and the negative to the negative cable I HAVE removed from the aux. Usually overnight on the trickle charger once a month does the trick.
Doug..almost certain you meant "and the negative to the negative cable I HAVE removed from the main battery. It's still connected to the aux, right....which is why tapping the cable's loose end is a direct line to the Aux battery's negative post?
 

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Agreed. Disable ESS and replace primary battery with a better one near the end of it's life.



You're better off getting a Lithium battery isolator and a LiFePO4 Deep Cycle Battery. Twice the power, half the weight. What's back up power?
@DaltonGang : as long as you stay in Houston proper, sure, temperatures are unlikely to get cold enough to make a LiFEPO4 battery problematic.

If you do head to parts freezing, I'd still advise an AGM like the vehicle battery chemistry.

I don't know about @Joe's Lithuim Battery Isolator enoufh to comment, but I'm a little concerned using the vehicle's alternator to charge the LiFEPO4 battery. Maybe the isolator makes it ok.
 
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DaltonGang

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@DaltonGang : as long as you stay in Houston proper, sure, temperatures are unlikely to get cold enough to make a LiFEPO4 battery problematic.

If you do head to parts freezing, I'd still advise an AGM like the vehicle battery chemistry.

I don't know about @Joe's Lithuim Battery Isolator enoufh to comment, but I'm a little concerned using the vehicle's alternator to charge the LiFEPO4 battery. Maybe the isolator makes it ok.
I did replace my original with an AGM battery. After researching them I went with the AGM, because of their longevity, power, and less terminal mess.
 

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I am now also a "disconnected" aux battery advocate.

I had noticed changes in my voltage recently where my voltage was "staying" more often into the 14+ volt while driving and I had some weird random dash lights act up on start-up a few times so I decided to do the aux battery disconnect to see if what I had read was possible (my aux battery could be slowly draining my main).

The disconnect took like 5 mins including taping and zip-tiying the aux battery wire to isolate it. Right after the procedure and for a few days, my voltage was in the 14+ still but then after those first days, its now almost always averaging low 13's and appears to only be going in the 14s once in a while. I do have the ESS deactivated like previously as well.

So not sure if my aux was starting to drain (prevent charging) of my main battery but my jeep seems to act more "normal" electrically so its looks like it may have been and I'm very happy with the disconnect now.

So thats all a long text to say, I support the 5 mins disconnect (remove fuse, tape neg of aux to isolate it)...it just takes something thats not necessary out of the equation. One less part to break and create issues, I never understood the need for a second battery from factory if your not having loads of accessories or winch to deal with etc which if I ever need a second one, I'll go Genesis but my needs aren't there at this time and the disconnect works very well for my usage (daily mostly with sporadic off-road use).

I'm still using the factory OEM main battery btw, 2019 vehicle with 115000 km on odo. ../crosses fingers it'll last a while longer now with the disco.

I think its possible the reputation of the stock main battery is based on the fact too many people gget cought by an aux battery thats preventing a good recharge of the main oem battery and by the time they catch it, its too late and both are damaged beyond repair. Save your oem main battery, lets disco!...:D
 

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Doug..almost certain you meant "and the negative to the negative cable I HAVE removed from the main battery. It's still connected to the aux, right....which is why tapping the cable's loose end is a direct line to the Aux battery's negative post?
Sorry, yes, you are correct. Fixed.
 
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DaltonGang

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I am now also a "disconnected" aux battery advocate.

I had noticed changes in my voltage recently where my voltage was "staying" more often into the 14+ volt while driving and I had some weird random dash lights act up on start-up a few times so I decided to do the aux battery disconnect to see if what I had read was possible (my aux battery could be slowly draining my main).

The disconnect took like 5 mins including taping and zip-tiying the aux battery wire to isolate it. Right after the procedure and for a few days, my voltage was in the 14+ still but then after those first days, its now almost always averaging low 13's and appears to only be going in the 14s once in a while. I do have the ESS deactivated like previously as well.

So not sure if my aux was starting to drain (prevent charging) of my main battery but my jeep seems to act more "normal" electrically so its looks like it may have been and I'm very happy with the disconnect now.

So thats all a long text to say, I support the 5 mins disconnect (remove fuse, tape neg of aux to isolate it)...it just takes something thats not necessary out of the equation. One less part to break and create issues, I never understood the need for a second battery from factory if your not having loads of accessories or winch to deal with etc which if I ever need a second one, I'll go Genesis but my needs aren't there at this time and the disconnect works very well for my usage (daily mostly with sporadic off-road use).

I'm still using the factory OEM main battery btw, 2019 vehicle with 115000 km on odo. ../crosses fingers it'll last a while longer now with the disco.

I think its possible the reputation of the stock main battery is based on the fact too many people gget cought by an aux battery thats preventing a good recharge of the main oem battery and by the time they catch it, its too late and both are damaged beyond repair. Save your oem main battery, lets disco!...:D
That Aux Battery is a parasite on our Jeeps. If I were to do it all over again, with what I know now, I would disconnect the Aux Battery the day I purchased the Jeep new.
 

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DaltonGang

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After 50k miles of having the A! I will be trying this (disconnecting the aux battery) tomorrow while I also replace my 72k mile alternator.
What happened to the Alternator??

.
 

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I did the bypass as prescribed. Drove for 120 trouble-free miles, then noticed the check-engine light is on today. Took it to a buddy with a scanner, and all the various trouble codes that displayed are voltage related. My voltage reading while running is 14.2.

Let me add that I replaced the main battery 120 miles (2 weeks) ago.

any ideas?
 

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...as long as you stay in Houston proper, sure, temperatures are unlikely to get cold enough to make a LiFEPO4 battery problematic.

If you do head to parts freezing, I'd still advise an AGM like the vehicle battery chemistry.
+1. We were just discussing this issue earlier today on a motorcycle forum that I frequent.

The Achille's Heel of lithium iron phosphate battery chemistry is the special handling required during low temperatures...specifically, the need to pre-warm them for proper function, usually by turning on the headlights to create the current draw, or load, that causes them to heat up a bit and thus provide proper cranking amps. That's all a bit precious for many of us that just want to start our cars or bikes and get on with the day.

Absorbent Glass Mat batteries work reasonably well in modern automobiles. That's what I purchase for my vehicles, and recommend for folks who live where it gets properly cold.

If lightweight LifePO4 batteries were practical for the general automotive market, the OEMs, in their obsessive chase to reduce vehicle weights to meet fuel economy targets, would be installing them in new vehicles as a matter of policy.

Note that cell phones and electric vehicles use lithium ion batteries, which is a whole 'nother subject.
 

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What happened to the Alternator??

.
It decided to quit on me. seems a bit premature but had it tested and I was driving around with a battery at 11.6V before I through a new one in.

I also want to add that disconnecting the AUX negative and pulling the F42 fuse has solved my A! light. If anyone cares the codes it was throwing while it was on were P00FD & U0010 (Medium Speed CAN Comm Bus)
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