ESS Dual Battery Management

[Jebiruph]

If the ESS system is operating only through the main battery, it can only perform ESS stop-start at the maximum of 6 times in a trip? (trip is starting cold -> driving -> and stopping the vehicle intentionally)

Why is that 6 times - and not based off of the charge left in the battery to allow it to cold start if needed.

The system monitors the voltage of both batteries during an ESS event and expects to see a difference between the battery voltages. When the voltages match for a predetermined 6 events, the system assumed to be malfunctioning and is disabled.

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[21JLURDG]

I've always thought it would be good to be able to isolate the aux battery and keep it as a reserve battery, especially when overlanding. Here's what I've come up with to implement that, and for managing the batteries in general. It uses a battery switch connected to the aux battery ground cable, a bypass jumper and a voltage gauge for each battery.

...The red cables connect to N1 and the main battery positive terminal.

@Jebiruph
RE: https://www.jlwranglerforums.com/forum/threads/jumperless-aux-battery-bypass.95945/

Based on your new information on pulling F42 and disconnecting the AUX negative, can you update the wiring diagram for installing the gauges? Would it be correct to connect the green wire from the gauge directly to the main +, and the blue from the gauge to the N1? Or better yet, just use the dual gauge (single meter) red wire connected to the main + and the two black wires to the two different sides of the battery disconnect switch?

Is there still a benefit to using the jumper if we carry the spare high current fuse array?

BTW, you have my vote for most significant contributor to the JLWF.

 

[Jebiruph]

@Jebiruph
RE: https://www.jlwranglerforums.com/forum/threads/jumperless-aux-battery-bypass.95945/

Based on your new information on pulling F42 and disconnecting the AUX negative, can you update the wiring diagram for installing the gauges? Would it be correct to connect the green wire from the gauge directly to the main +, and the blue from the gauge to the N1? Or better yet, just use the dual gauge (single meter) red wire connected to the main + and the two black wires to the two different sides of the battery disconnect switch?

Is there still a benefit to using the jumper if we carry the spare high current fuse array?

BTW, you have my vote for most significant contributor to the JLWF.

Thanks for your vote, you are obviously very wise.

Here's an updated diagram. The trick to this setup is that it's the ground wires that differentiate between the different batteries, both gauges use the same 12v power.

 

[Jebiruph]

You could run separate power wires to each battery, but since both battery's positive terminals are connected except during an auto stop, running separate wires will only make a difference during an auto stop.

 

[CaJLMetalHead]

Nice setup Jebiruph ... I wonder if anybody has done dual batteries connected in Parallel .. with that I mean either using a larger battery for the ESS/AUX or... disable the ESS Battery and install a similarly sized / same chemistry battery somewhere in the rig and simply connect it in parallel with the main one.. either directly or using a Battery Isolator being controlled by the ignition... the same way guys with BIG Stereo speaker/amplifiers use..

 

[Jebiruph]

Here's my updated battery voltage monitoring solution. It's similar to the one here https://www.jlwranglerforums.com/forum/threads/ess-dual-battery-management.60034/post-1370003 , but this one has LEDs on the leads to indicate which lead is active.

 

[Jebiruph]

Here's my as simple as possible dual battery voltmeter design including a mount which can be velcroed to the top of the battery or bolted to the inner fender. This is what I plan on installing in my JL and JT to be able to get a quick voltage reading from either battery (when the aux battery is disconnected). The mount is a piece of .1" HDPE.

 

[LanceMagnum]

I did a very simple version of this when it was time to replace my aux. I'm using the Braille battery with more cranking amps than OEM, and a simple disconnect switch so I can go from isolated aux (plus fuse pull) to having the aux battery in the circuit when I want to keep it charged.

The disconnect switch can handle 500 amps surge which is more than the aux battery can put out in an emergency start situation.

I peeled back some of the tape holding the two negative cables together to get the 'S' curve in there.

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