Battery Voltage when srart/Stop engaged

[Altitude2020]

I am wondering what other owners of a 3.6 Ess with aux battery gauge indicates when auto start is engaged and engine is off

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[Gregj]

That’s about right, it will restart if it goes much below that.

Gregj

 

[Altitude2020]

That’s about right, it will restart if it goes much below that.

Gregj

Thanks, this is what it is when it starts.

 

[Gregj]

Working as expected. Perfectly normal.

Gregj

 

[Reinen]

Thanks, this is what it is when it starts.

That's what the voltage is when your alternator is fully operating and charging the batteries, which is to be expected after a start. The batteries never put out 14+v. A new fully charged battery will be 12.7-13v. An old battery on its last legs may only go up to 12.4v when fully charged.

ESS will restart the engine if it dips below 11.9v.

 

[Gregj]

I’ve never seen mine dip that low, it always restarts at 12.2.

Gregj

 

[andy29847]

The vehicle voltmeter show voltage under load. Unloaded battery voltage would be higher.

In a stop/start event, the vehicle voltmeter shows aux battery voltage.

All other times the voltmeter shows the 2 batteries combined.

The stop/start system seems to get a little funky when actual battery voltages get near 12.4.

A career that led to some knowledge about battery systems, and 6 months of struggle with the dealer when my batteries got old, caused me to develop a strong opinion about the Jeep battery system. I wrote a couple of post to entertain myself. Maybe you'll like them too.

https://www.jeepgladiatorforum.com/...teries-and-charging-system.75512/post-1231320

https://www.jeepgladiatorforum.com/...remium-h7-group-94-battery.76866/post-1254668

 

[garykk]

I’ve never seen mine dip that low, it always restarts at 12.2.

Gregj

Ummm…his voltmeter shows 12.3?

 

[Mguy]

.
The stop/start system seems to get a little funky when actual battery voltages get near 12.4.

Battery voltage under load is not a particularly useful measurement unless the amperage is known and consistent. Would be nice if our Jeeps told us amps.

 

[Pape]

Depending on the load, I would say your battery will be soon good for replacement.

Also note charging voltage change with the battery temperature, here I have see as high as 14.8v charging in the winter time

 

[Gregj]

Ummm…his voltmeter shows 12.3?

I was replying to @Reinen who said his drops down to 11.9, ?‍. Maybe read all the posts in the thread.

Gregj

 

[Gregj]

Something a lot of folks miss in the whole ESS mess is ESS working means the Jeep has tested your batteries and found them to be in good condition. A good sign your batteries have problems is ESS stops working. You will never notice that sign if you always disable ESS.
Gregj

 

[Reinen]

Something a lot of folks miss in the whole ESS mess is ESS working means the Jeep has tested your batteries and found them to be in good condition. A good sign your batteries have problems is ESS stops working. You will never notice that sign if you always disable ESS.
Gregj

That's exactly why I keep ESS enabled when I'm not on the trail. Where I go (the SW desert w/ no cell service) a surprise battery failure will be at best a very expensive recovery and at worst life threatening. The moment ESS refuses to engage two new batteries are being ordered ASAP and I'm no longer venturing far.

And to put my 11.9v and everything else into perspective, my OEM batteries are just shy of 3.5 years old. ESS and everything else is still working fine though. I will replace the batteries before summer because I know I'm pushing it with those crappy OEM batteries.

I attribute the longevity of my OEM batteries to two things:

1. My JL was ordered and it sat on the dealer lot for less than 24 hours. As opposed to a lot purchase that could have been sitting on the lot for months. Dealers don't run the engine or charge the batteries of their lot stock and sitting that long without a recharge severely reduces the lifespan of the OEM batteries.
2. My JL is not a DD and often sits for a week without use, which is bad for battery longevity. I installed a Cascadia 4x4 Hood Solar Panel to insure the batteries are trickle charged every day.

 

[Bandit59]

I am wondering what other owners of a 3.6 Ess with aux battery gauge indicates when auto start is engaged and engine is off

Your good. Mine got down to 10.1 with engine off. Mine was done

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