Genesis DIY dual battery tray wire layout

[SpookyXJ]

http://www.genesisoffroad.com/2018-2020-Jeep-Wrangler-JL-DIY-Kit_p_62.html
I ordered this last night and got a ship notification this afternoon. I wanted to go a bit simpler than the standard setup plus its a bit cheaper. My main concern is the stock system is not isolated when the vehicle is off potential greatly reducing battery life especially considering that the 2 batteries are not the same size and make.

Goals:
-Make the Aux and main batteries the same size/model
-Isolate the batteries when the ignition is off
-Retain ESS battery isolation during an ESS event
-Have all accessory loads connected to the aux battery
-Have more power in reserve for winching
-Have the rear 12v outlet run off the aux battery when batteries are isolated

Special thanks to @Jebiruph for all the diagrams you have made. Its making figuring this out a lot easier.

Diagram of my plans(Sorry hand drawn)

I'm currently planning to use a Cole Hersee 24231 200 amp continuous duty solenoid to Isolate the batteries. I will eliminate the wire from n3 on the PDC fuse bar to the PCR to the Aux battery. Replace N1 to aux positive with a longer cable.Reuse or replace N2 to main positive. Tap a 12v switched ignition source from the fuse box to trigger the battery isolation relay through a secondary normally closed relay that will be triggered by the factory PCR trigger wire. Also going to keep the IBS sensor on the main battery and ground with the aux battery. All add ons will connect to the aux positive.

I've seen that you can make the rear 12v outlet hot all the time by moving a fuse. Does anyone know if this is powered by the aux battery via N1?

I'm also not sure what batteries I'm gonna go with. Most of the group 25's are 550 CCA's and I don't want to go that small.

I'd love to do the Odyssey's but they are expensive. I don't really want to spend that much on a wear item. Exide and Bosch make AGM group 25's with decent CCA's but they are not available to me locally or online plus the Exide has bad reviews. Looking at the Optimas good CCA's and they should fit but will be loose in the tray without a spacer. They also have less than stellar reviews since the factory got moved to Mexico. However I can get a pair shipped for $330. That leaves NAPA Legend 625 CCA's regular lead acid but slightly longer than standard group 25's @ 9.75" currently listed at $112 each + core at my local Napa. Will measure to see if they fit once I get the tray. Anyone know of any other options out there?

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[k9runner]

Check dimensions on group size 34R batteries, I’m guessing you’ll be able to find some that will fit.

 

[SpookyXJ]

Check dimensions on group size 34R batteries, I’m guessing you’ll be able to find some that will fit.

I think they will be too long to fit but I'll measure the tray once I get it. Should be here Tuesday.

 

[cosine]

please take pics of the install. i'm thinking of doing the dual battery setup, perhaps later on down the road.

 

[Brian0128]

Have you thought about using the Redarc 25 instead of a solenoid. The benefit of being a DC to DC charger with solar input seems like a good idea.

 

[SpookyXJ]

Have you thought about using the Redarc 25 instead of a solenoid. The benefit of being a DC to DC harder with solar input seems like a good idea.

No I was not even aware of its existence. Interesting solution but very pricey plus I want to keep the operation the same as factory except add isolation when the ignition is off.

I've already ordered all my solenoids and wiring only thing left to buy is the batteries. I'm gonna wait till I get the tray to measure to see what other group sizes I might be able to squeeze in.

I went to Walmart earlier and measured other group size batteries while I was there. They have a group 86 same length, width, and post layout as their group 25 but a little shorter in height. 650 CCA $120. I'll probably just go with that. I've had decent luck with everstarts in the past and its a 3 year free replacement 5 year prorated battery. Last one was on my Samurai over 5 years old and starting to get weak when I sold it but still working. There are also a couple of 690 CCA group 86's here in town at Napa and Orielys $140 & $160 respectively so plenty of choices for replacement.

 

[SpookyXJ]

OK got the battery tray and the maximum length it will fit for the bottom of the battery is 9". Available width is 13 7/8". Minimum hold down height is 7 7/8". That's pretty limiting on what you can fit in there. Lid has all the studs on it for the regular kit with rubber covers. I'm using the same solenoid Genesis uses so it lines up perfectly.

Everything showed up today but my cables which should be here Thursday. Won't have time to install until Saturday.

 

[Jeepjunkie]

Sub’d
Keep the info coming, I’ll go this route someday and this is helpful stuff!

 

[SpookyXJ]

Well I got all the stuff I needed to get this done on Friday and I also got the flu on Thursday so Its not done and won't be this weekend.I felt decent enough today to go ahead and wire up what I can inside where it's warm.

I ended up buying 2 of the group 86 Everstart 650 CCA from Walmart perfect length and width and 3/4" too short in height. I made a spacer out of a bit of 3/4 ply I had lying about so the tray lid fits snug. $270 out the door for both with taxes and one core charge so it would run about $250-255ish if you have both cores.

I kinda regret going with the military style terminals think they are going to be a bit inconvenient when I hook everything up to them.

Since I'm setting this up to be wired basically the same as stock I decided to add in a boost switch to my MLC-6 just in case the jeep ever decides not to allow a crank. Now that I think about it's completely pointless since the MLC-6 will be on the aux battery but I've been trying to figure something to go on the final switch position and jumped at the chance for it not to be more lights . I added in a Roadmaster diode between the 2 relays to take care of any potential backfeed. Anyway I can manually combine the batteries with the flip of a switch as long as the aux battery has power. I'd blame it on the cold medicine but I ordered all that stuff before the flu. Props to OTRATTW they will make you a custom switch cover and send it out fast.

FYI the studs on the top of the battery hold down are 10-24.

I would not recommend buying any battery off of advertised dimensions. None of the batteries I measured matched their published specifications. Measure in person before you buy. Length and width at the bottom of the battery are the critical dimensions.

 

[TroyBoy]

Looks really good. What is the difference between your wiring setup and the full genesis kit?

 

[SpookyXJ]

Looks really good. What is the difference between your wiring setup and the full genesis kit?

The Genesis kit uses a smart Isolator. Quote from their website on how it operates:
"

• When both your batteries are fully charged at 13.2 volts, they are automatically connected and are charged at the same time.
• When you park and turn off the engine, but continue to use accessories such as lights or the stereo or a CB, both batteries begin to drain down.
• When your main cranking battery reaches 12.7 volts, the smart isolator separates the batteries, so that your cranking battery will have enough power to start the engine. The second battery continues to power your accessories for as long as it will last.
• After you crank the vehicle, your main cranking battery will be charged up to 13.2 volts first, and then the isolator will allow the charging of your accessory battery. By only charging one battery at a time, your alternator is protected from excessive strain."

Plus their Diagram:

With the factory setup the aux battery supplies power to everything on N1 which is all stuff powered during an ESS event. The main battery supplies power to everything on N2 and the rest of the fused busbar. Whenever there is not a ESS event (99% of the time) N1 and N2 are connected together through N3 by the ESS PCR relay. So for the vast majority of the time the 2 batteries are connected in parallel. The Genesis kit connects the Aux battery terminal to the main battery terminal so it's basically acting like a jumper for N1 & N2 making the PCR redundant.

As Illustrated through Jebiruph's Diagram:

So with the Genesis kit the cranking battery powers everything factory on the jeep and ESS events do not isolate the batteries. Only aftermarket stuff(loads you attach to the aux busbar) will be isolated in the event that main voltage drops below 12.7 volts so say you leave your freezer fridge plugged in to the rear outlet it's gonna draw from the main battery. It's also not clear to me whether or not the genesis kit separates both batteries when the ignition is off but the way their site reads I dont think it does.

The smart Isolator has some advantages over my setup namely more of a guarantee that one battery will always have charge but I want all the aux loads on the aux battery including the factory stuff that's powered during an ESS event.

The way I'm wiring it is pretty much like factory except the batteries are isolated when the ignition is off. I'm just using 2 relays without a smart Isolator. The big 200 amp relay acts as the isolator and I have a small normally closed 40 amp relay replacing the PCR relay to isolate the batteries during an ESS event. The big relay is triggered by a 12v ignition source which I will tap out of the fuse box. Anytime the ignition is on the batteries are combined. Off they are seperated. The small relay(normally closed) is triggered by the PCR trigger wire so an ESS event separates the batteries.

I'm one of those masochists who likes electronic start stop but just disagrees with how FCA has 2 dissimilar size batteries wired together in parallel when the batteries are at rest so they are constantly eating away at each other.

I hope that's not too long winded and at least remotely clear.

 

[Bob Burd]

Love the diagrams and effort you put into this. A concern I have (which may not be real):
Suppose you drain the aux battery with a wild evening of disco lights in the desert (or whatever). When you go to crank the engine in the morning you're going to short a good main battery with the drained aux. That seems like a lot of current, limited only by the wire/solenoid resistance. Would a heavy duty resistor (say 5-10ohms) make sense to limit the current?

 

[Genesis Offroad]

@SpookyXJ I love to see custom configurations! Keep the pics coming!

Oh and you are correct that our smart isolator connects/disconnects the batteries based on the voltage levels, not based on the ignition status.

 

[SpookyXJ]

Love the diagrams and effort you put into this. A concern I have (which may not be real):
Suppose you drain the aux battery with a wild evening of disco lights in the desert (or whatever). When you go to crank the engine in the morning you're going to short a good main battery with the drained aux. That seems like a lot of current, limited only by the wire/solenoid resistance. Would a heavy duty resistor (say 5-10ohms) make sense to limit the current?

On the resistor I'm not sure it's been a looong time since I had an electronics class (25ish years). I've slept a lot since then.

In your scenario with my wiring the solenoid would be the fuse. There are some car audio solenoids with a 500 amp continuous rating but I'm not convinced of the quality. I am gonna make a short jumper cable and carry it with me jic the solenoid ever fails.

Sorry I have not finished this the flu lingered and I have a severe lack of motivation.

 

[unsavory]

I think Bob's concern was more around the fact that you would essentially be charging a drained battery at 200 amps off of your main battery, when the vehicle starts.

This may or may not be a concern for some batteries. I know the Odyssey batteries can take that kind of inrush current, but not all batteries can.

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