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4/26/19 Since writing this thread, @Jebiruph has done some testing that suggests the changes below, written in this color.
Plenty of excellent threads have been written about how to jumpstart the 3.6L JL. How things get hooked up, in terms of what cables to place where, and in what order are no different than jump starting pretty much any other ICE (internal combustion engine) vehicle. Even allowing the booster vehicle to run a few minutes is the same. But what is going on behind the scenes during that waiting period, I believe, is different than in most other ICE vehicles and this thread's focus. If I've got it wrong, do correct.
A fair number of you know this and another group just wants to know the procedure, not what's happening. This post is for those who want to know how and why. It's long, but there's nothing I feel I can drop from it.
Before explanations you'll have to except some facts. And before hearing those facts you'll have to understand some basic electric concepts many of you may already know:
Concepts
What's a relay? It's an electronic switch. "Oh, like the one on my wall that operates the lights?" No. That's a manual switch. It controls electronics--true-- but you manually exerted the effort with your fingers to change its state. Relays are all over the place, especially in vehicles. They come in handy when two electric devices work in tandem, but run on different electrical systems, sometimes at different voltages, or even alternating versus direct current. Example, when utility A/C power drops at home, a switch tells the generator to turn on, and crank off its D/C battery. There's more to relays, like N.O. and N.C ones (normally open/normally closed) but beyond need to understand here.
What's a parallel connection between batteries? Its when all the negative terminals of two or more batteries are connected together to form one negative, and the same happens separately for all the positive terminals. Voltage remains fixed, amperage is increased. That's the layperson's explanation.
Electric Facts in the 3.6L JL
But why?
The implications
The hack
@Jebiruph has posted and explained a great method whereby the batteries always remain connected in parallel. It's only 2 **possible** concerns for me is that if you allow ESS to engage with this hack, power is drawn from both batteries during an ESS event, leaving the main battery less capable of powering the starter. It is a theoretic concern of a technique Jerry researched, tried, tested, reported, and we benefit from. Second, the 3.6L ***may*** be allowed to enter into ESS mode, even if the ESS battery is low, possibly getting a false higher reading because of its permanent parallel connection to the main battery with this hack.
(Other Chrysler rigs with ESS and one battery do this without problems, and I can't see this hack hurting the 3.6L, although your dealer may not love it. I want to make it clear, IMHO Jerry deserves cudos, not critiques.)
Edit: I don't think I properly and expressly conveyed the beauty of Jerry's hack, which is this. With it, the batteries are always connected in parallel, 100% of the time (not 99.99% of the time) and no longer is the starter relay dependent on the ESS battery alone having enough energy to make it run. Either/both batteries are capable of doing this with his hack.
The jump start at last
That's just it. You're not just jump starting. Hook those cables up as usual and wait a few minutes, and what's happening is that you are charging both batteries, most importantly here the ESS battery. True, the same is happening during the waiting period in a one battery vehicle jump start but it's not really that your allowing the donor vehicle's battery to charge here. Rather you're allowing the ESS battery in the 3.6L JL to build up current. Parked on your driveway those batteries are in parallel. So the charge to your main battery is flowing to your ESS. And that's important because in a moment you're going to press that start button, the 3.6 JL is going to isolate those batteries under your hood (and as result of following the manual and connecting the jump start leads to the main 3.6L battery, the donor battery from the ESS battery) , and the ESS battery on its own, as discussed above, will be responsible for energizing the starter relay.
This may explain why your off the shelf portable chargers don't work (well) here. They tend to be designed to offer lots of current in a short period of time to energize the starter, not charge the batteries (drawing out current from these power packs) and THEN energizing the starter.
Final Thoughts
Can you just directly connect the jumpers to the ESS battery and get going quicker short of digging that sucker out (it's quite well buried under the hood)? I don't know. @Jebiruph might.
Peace. : - )
~~~~~~~~~~~~~~~~
Plenty of excellent threads have been written about how to jumpstart the 3.6L JL. How things get hooked up, in terms of what cables to place where, and in what order are no different than jump starting pretty much any other ICE (internal combustion engine) vehicle. Even allowing the booster vehicle to run a few minutes is the same. But what is going on behind the scenes during that waiting period, I believe, is different than in most other ICE vehicles and this thread's focus. If I've got it wrong, do correct.
A fair number of you know this and another group just wants to know the procedure, not what's happening. This post is for those who want to know how and why. It's long, but there's nothing I feel I can drop from it.
Before explanations you'll have to except some facts. And before hearing those facts you'll have to understand some basic electric concepts many of you may already know:
Concepts
What's a relay? It's an electronic switch. "Oh, like the one on my wall that operates the lights?" No. That's a manual switch. It controls electronics--true-- but you manually exerted the effort with your fingers to change its state. Relays are all over the place, especially in vehicles. They come in handy when two electric devices work in tandem, but run on different electrical systems, sometimes at different voltages, or even alternating versus direct current. Example, when utility A/C power drops at home, a switch tells the generator to turn on, and crank off its D/C battery. There's more to relays, like N.O. and N.C ones (normally open/normally closed) but beyond need to understand here.
What's a parallel connection between batteries? Its when all the negative terminals of two or more batteries are connected together to form one negative, and the same happens separately for all the positive terminals. Voltage remains fixed, amperage is increased. That's the layperson's explanation.
Electric Facts in the 3.6L JL
- There are two batteries, a smaller one tucked away: the ESS (Engine Start/Stop) or Aux battery if you prefer, and a main one. This is well and better discussed in other posts.
- These batteries are always hooked up in parallel (99.9% of the time) except when:
- The ESS system is engaged. In this case your main battery rests and your ESS battery runs things like the radio and lights.
- The engine needs to crank, be it a cold start in your driveway, or when taking your foot of the brake as the traffic light turns green, or the 3.6L takes you out an ESS event because the ESS battery is running low, and in either of these latter two cases (foot off brake or low ESS battery), the 3.6L takes you out of an ESS event.
- At the point where the engine needs to turn over, regardless of whether you push the start button, or take your foot off the brake at a just made green traffic light, during an ESS event, or the ESS battery becomes discharged during an ESS event and the 3.6L automatically takes you out of the ESS event or you remote start the 3.6L JL with your accessory remote start on your key fob:
- The 3.6L breaks the (parallel) link between the two batteries.
- A test of the ESS battery's current is effected. If inadequate, the start process fails.
- The ESS battery becomes solely responsible for energizing a starter relay, which tells the starter to work.
- The two batteries are reconnected back into parallel, and then....
- The starter is energized by both batteries (because they're back in parallel) to crank the engine.
But why?
- The main battery is saved during an ESS event to bear the primary responsibility for turning the energy drawing starter. Once the engine cranks, the batteries are recharged from the alternator, powered itself from the engine. This is why an ESS event may end early if the ESS battery becomes too discharged: it still needs enough power to energize the starter relay.
The implications
- You could replace your main battery with one producing 12V and capable of delivering 7 trillion amps, coming right off the steam turbines of a nuclear power plant, but with no ESS battery power, you get no crank. Conversely, remove the main battery, and your 3.6L should work provided the ESS battery has enough power to energize the starter relay AND crank the starter.
The hack
@Jebiruph has posted and explained a great method whereby the batteries always remain connected in parallel. It's only 2 **possible** concerns for me is that if you allow ESS to engage with this hack, power is drawn from both batteries during an ESS event, leaving the main battery less capable of powering the starter. It is a theoretic concern of a technique Jerry researched, tried, tested, reported, and we benefit from. Second, the 3.6L ***may*** be allowed to enter into ESS mode, even if the ESS battery is low, possibly getting a false higher reading because of its permanent parallel connection to the main battery with this hack.
(Other Chrysler rigs with ESS and one battery do this without problems, and I can't see this hack hurting the 3.6L, although your dealer may not love it. I want to make it clear, IMHO Jerry deserves cudos, not critiques.)
Edit: I don't think I properly and expressly conveyed the beauty of Jerry's hack, which is this. With it, the batteries are always connected in parallel, 100% of the time (not 99.99% of the time) and no longer is the starter relay dependent on the ESS battery alone having enough energy to make it run. Either/both batteries are capable of doing this with his hack.
The jump start at last
That's just it. You're not just jump starting. Hook those cables up as usual and wait a few minutes, and what's happening is that you are charging both batteries, most importantly here the ESS battery. True, the same is happening during the waiting period in a one battery vehicle jump start but it's not really that your allowing the donor vehicle's battery to charge here. Rather you're allowing the ESS battery in the 3.6L JL to build up current. Parked on your driveway those batteries are in parallel. So the charge to your main battery is flowing to your ESS. And that's important because in a moment you're going to press that start button, the 3.6 JL is going to isolate those batteries under your hood (and as result of following the manual and connecting the jump start leads to the main 3.6L battery, the donor battery from the ESS battery) , and the ESS battery on its own, as discussed above, will be responsible for energizing the starter relay.
This may explain why your off the shelf portable chargers don't work (well) here. They tend to be designed to offer lots of current in a short period of time to energize the starter, not charge the batteries (drawing out current from these power packs) and THEN energizing the starter.
Final Thoughts
Can you just directly connect the jumpers to the ESS battery and get going quicker short of digging that sucker out (it's quite well buried under the hood)? I don't know. @Jebiruph might.
Peace. : - )
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