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Discussion Starter #1
All, I have an urgent request. I'm having some starting issues with my 2011 JK (~70k miles). Twice now, I've had trouble starting the jeep either first thing in the day or after it's sat idle for 8+ hours (both times outside temperatures were 60+). Each time, jumping it worked and then all was well. But I had used the jeep many days in between.

To add something to the mix, a week ago I also hit a deer. I got off lucky, just grazing it, and only had to replace the right turn signal lamp and right headlight bucket. The turn signal connector was slightly damaged (picture) but just looks like plastic damage, not wiring. (And even if there was a short in that connector, it's rarely on so shouldn't drain battery overnight, correct?)

Here's a timeline of events since the deer accident:

9/1 pm: Hit deer

9/2 pm: Took grill off to assess damage, disconnected right headlight and turn signal lights

9/3 pm: Started jeep and drove into town, no issues
(don't remember if I drove on the 4th or 5th)

9/6 am: Jeep won't start, just click. Jumped, just fine. Drove for many hours that day

9/7 am: Jeep starts just fine, temperatures in the 30's
(don't remember if I drove on the 8th or 9th)

9/10 am: Jeep starts just fine in the morning, drove a few minutes into town and back.

9/10 pm: Take grill off, install new turn signal and headlight, tested without running engine but only for 2-3 minutes. 2 hours later, Jeep is sluggish to start but does. Ran errands including going to NAPA and having the battery and alternator tested (just the thing they input your CCA, check non-running voltage and then check running voltage). Battery tested at 12.8v, charging at 14.something.

9/11 am (today): Checked battery in the morning, 12.35V. 2 hours later, try to start, won't start. After trying to start, battery at 11.2V. Jumps fine. Ran for 15 minutes, charged at 14.4V. After that battery at 12.8V. Stopped engine, started again and after 1 minute stopped. Battery at 12.7V.


My wife was going to take the jeep tonight through the weekend up into the mountains (just high clearance roads, nothing a stock SUV couldn't do) this weekend but don't want her to have any issues.

The alternator seems to be charging just fine. After jumping the vehicle works fine even with a number of stops/starts, so I'm not sure I should suspect the starter. Battery tested fine at NAPA and the vehicle is only 3 years old with 70k miles, I guess I'm a little hesitant to think it's the battery, but this seems the most likely culprit to me at this point. I inspected the wiring in headlight and connectors... They seem fine. And headlights/turn signals shouldn't have any current when jeep is sitting while off, so I don't think that could be the cause.

Now, battery terminals do show corrosion, I've never cleaned. I'm going to try and get a wire brush and clean those and the connections either way.

Thoughts on what this could be?


Thanks for the help,
Ryan
 

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Clean your battery terminals and check to make sure that the connectors are tight on the terminals. Take your battery someplace that will load test it.
 

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'11 and the stock battery? Swap it, you have a cell going bad. The clock is ticking until it shorts out completely.

Bob K.
 

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Discussion Starter #6
Thanks for the help all!

Right after posting this I went out and cleaned the terminals really well and checked the battery cables... After doing that, battery was again down at 11.4V. Jumped it and went to batteries plus. It tested at only 400 CCA (rated 600). Just ended up replacing it with a Duracell Ultra Premium. Can't find many things said about the battery, which concerns me a little. But it has a 4yr warranty and rated at 775CCA AGM and had a $10 in store rebate...

Hopefully that will last me awhile.

Thanks again.

Ryan
 

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In my mind, there's a couple of things.

1: get a new battery. It's time anyway. This may not solve the problem though.

2: the quick drop in volts tells me that there is either a parasitic draw from somewhere, or the alternator isn't fully charging the battery. (Not producing it's rated amperage.)

Since you had a accident, I'm leaning towards a damaged alternator. Here's how to check.

1: turn the engine over. Take your voltmeter and put negative to negative and positive to positive on the alternator downstream of the battery. Check the amps to get against the rated amps your supposed to be producing. If the amperage you are reading is lower than the oem rating. Your alternator is damaged. If it is spitting out the correct amps, then you need to check your connection to the batt. Clean off all the corrosion and get the connections sparkling clean. Put the terminals back on and tighten them.

Report back.
 

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In my mind, there's a couple of things.

1: get a new battery. It's time anyway. This may not solve the problem though.

2: the quick drop in volts tells me that there is either a parasitic draw from somewhere, or the alternator isn't fully charging the battery. (Not producing it's rated amperage.)

Since you had a accident, I'm leaning towards a damaged alternator. Here's how to check.

1: turn the engine over. Take your voltmeter and put negative to negative and positive to positive on the alternator downstream of the battery. Check the amps to get against the rated amps your supposed to be producing. If the amperage you are reading is lower than the oem rating. Your alternator is damaged. If it is spitting out the correct amps, then you need to check your connection to the batt. Clean off all the corrosion and get the connections sparkling clean. Put the terminals back on and tighten them.

Report back.
Please don't do this
 

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^^^^^Agree, do not do this ^^^^^

Sounds like you did the right thing with a new battery.

Brief explanation as to why the above test is not a good idea.
If you set a multimeter to amps it has to be connected "in circuit". If you put the leads across the +\- terminals you are actually putting a short across your battery. At best you'll blow the fuse in the meter.

Also, a circuit only draws the amps it needs. The only way to test the battery is to use a tester that will simulate the max load and measure the voltage under that condition.
 

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I posted that before I saw he fixed it.

And the way I posted is the proper way to check alternator output, not battery voltage.

I would love to know how you people check the amperage output of an alternator without doing it this way.
 
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