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Discussion Starter · #1 ·
I did not see anything related with a simple search.
I am finding that the 3.8 engine in my JK is slow to crank after driving it and getting the engine up to operating temp for a good five mile each way drive.
after the engine sits for a good 20 minutes and the ambient temps increase under the hood I am noticing slow cranking from the engine. I know there is a heat shield on the starter which I assume is to aid with this since the converters are very hot. I am assuming my yellow top is in good shape and I know my connections are tight. I have not taken cold and hot engine amp reading while cranking I have not noticed this issue with other JK's I have driven and was curious if others have the same issue or if I need to look deeper
 

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I wouldn't assume much on the battery. I'd at least stick a voltmeter on the battery while you think it's cranking slow
 

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I just changed my 2 yellows top for die hard platinums, I've gone through 3 yellow top in 2 yrs.
 

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I have a red top in the JK and it's lasted 3+ years so far. I was reluctant to put it in as I went through 2 yellow tops on a previous vehicle in very short time. I know a lot of people that have issues with Optima batteries, especially yellow tops.

It definitely sounds like a battery related issue.
 

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Discussion Starter · #6 ·
I have a red top in the JK and it's lasted 3+ years so far. I was reluctant to put it in as I went through 2 yellow tops on a previous vehicle in very short time. I know a lot of people that have issues with Optima batteries, especially yellow tops.

It definitely sounds like a battery related issue.

Thats what I figured it was.
I have a special battery charger for AGM batteries
i hooked it up this morning and it was showing about 50% charged
In the past I have connected the charger for 1-2 days until I get a green light for 100% then it can charge again to 100% capacity it has only been charging to about 50% capacity, Anyone with a yellow top or other AGM batteries may want to invest in one of the chargers. I have been using AGM batteries since 1995 and over the past few years this little charger has saved several which were thought to be bad batteries. I'll see if I can remember to post the info and hopefully with 100% charged I won't have any more slow hot cranks
 
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