Amperage to crank JLU 3.6L?

[Rahneld]

How much amperage would a booster power pack have to be rated at to crank a 3.6L JL Wrangler?

I do appreciate this question to be far more detailed that it would appear to be on its surface given the need for the ESS/Aux battery to have charge on its own for the crank process in the rig to even initiate.

So let me change the question a tad.

First, it's known fact that a charged ESS/Aux battery, even with the main battery disconnected, can crank a 3.6L JL. (The converse is not true.)

Suppose in theory I temporarily substituted the ESS/Aux battery for this power pack and also temporarily disconnected the main battery. Now no charge of the ESS/Aux battery would be required as the booster pack would effectively become this ESS/Aux battery. Nor would any of the booster packs power go into charging either battery (the main one temporarily disconnected.)

What amperage would be required under this scenario? And I ask this because people *may* be finding their booster packs inadequate due to their loss of power while they charge both batteries for a few minutes when connected to the main battery: itself connected in parallel to the ESS/Aux battery 99% of the time, including when the rig's engine is not running.

Thanks.

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[Headbarcode]

Not much to add because I didn't go with that engine, but I thought the main battery handled just cold starts and the aux battery handled just stop/start events?

 

[Rahneld]

Not much to add because I didn't go with that engine, but I thought the main battery handled just cold starts and the aux battery handled just stop/start events?

Here's where I'm going with this post:

I have a theory that people would not need to buy as powerful booster packs to get their dead 3.6L cranked as they do, if the technique for jumping the 3.6L changed to one where the ESS/Aux battery is temporarily replaced by the pack, and the main battery is temporarily taken out "of the picture" during such a crank. I believe this because no waiting period, where the jumping device first charges the ESS/Aux battery somewhat, might be necessary.

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On the 3.6L, both batteries are in parallel at the point of crank, be that crank cold or subsequent to an ESS event.

Before that crank will be attempted though the ESS battery alone much have sufficient power.

This is a non issue during ESS events. This is because the rig won't enter the ESS event if the ESS/Aux battery doesn't have sufficient power. Neither will it maintain the event once in it, until the user takes their foot off the brake, if that battery's power becomes too low during the event, rather re-cranking the engine prematurely need be.

The design's IMHO weakness though is that this same logic is applied during cold cranks and that no crank is attempted if the ESS battery alone lacks sufficient power. The main battery could have full power, the crank simply won't be attempted.

I would have preferred for either battery to have sufficient power, not that this is likely to happen because the batteries are connected in parallel at rest, and a dead battery may suck the power out of the one with power anyway. The forum has had great posts written on how to override this default behavior with jumpers: a great technique with its own situations under which (I think) it works best and doesn't.

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