2020 JL Battery Help

Jebiruph

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Since were talking about batteries, is there a way to check the ESS battery and the main battery separately with a voltmeter without disconnecting any cables? Thx, Ben
You have to disconnect something to isolate the batteries, disconnecting the aux ground cable from the main battery negative terminal is probably the easiest.
underhood jumper plain.PNG
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Gee-pah

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Can you use a packaged battery jumper?
Thinking of the Type S that Costco sells. I don't see how it can energize the small "hidden" battery. Would it work?
Dave:

On the 3.6L JL, both batteries are, most of the time, hooked up electrically in parallel. This means that placing your battery jumping or charging device on, say, the main battery's terminals (among other places) will charge both batteries when the vehicle is at rest.

The only time I know of that the batteries are isolated are, for the original 3.6L JLs at cold crank, for an instant prior to crank to test the ESS/AUX battery in isolation, and not proceed with the crank if this secondary battery lacks adequate charge, and during ESS events when this secondary battery runs most things (there's been talk that power steering is still run from the main battery---then again, ESS won't engage if the wheel is sufficiently turned.)

The implications of this, as I discussed above, is that your charging source needs to remain on the main battery terminals for a few minutes to give the ESS/AUX battery time to charge. Still more, a portable self contained jumping device may lack adequate charge to both charge the ESS/AUX battery and crank the starter---more of this at request.

As I stated, there has been talk on the forum about how this ESS/AUX battery and cold cranking may have changed it's logic in newer JLs, and speculation whether this change has or will be downloaded to older JLs such that we are no longer depending on this ESS/AUX battery having power for a cold crank to occur.

There are techniques on the forum for getting around this ESS/AUX battery dependency, available on request.
 

2mnycars

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We have the 2 L turbo engine JLU....we have the portable battery booster from Costco. I'm wondering now whether it's worth carrying.

Thanks Andy. May I send you a PM?
 
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Gee-pah

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We have the 2 L turbo engine JLU....we have the portable battery booster from Costco. I'm wondering now whether it's worth carrying.

Thanks Andy. May I send you a PM?
You may, but I am unfamiliar with the battery hookups in the 2L JL. :)
 

2mnycars

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Thanks Andy. I tried. Couldn't.
 
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