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Old 01-22-2011, 09:36 PM   #1
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Voltage Regulator/Alternator problem??

The first pic is the "normal" charge that I see all the time and the second pic is what has been happening lately at startup now that its freezing cold outside. Once the Jeep warms up to operating temp the charge drops back to the first pic range. May be nothing at all and its been this way forever and I just didn't notice before or there may be a problem...what say y'all? I was thinking it may be my voltage regulator going bad or alternator (still OEM) slowly dying.

pic #1 "Normal"

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pic #2 "Cold temp"

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Old 01-22-2011, 09:45 PM   #2
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As long as the volts go down I personaly wouldnt worry about it. If they climb and peak while you're driving then I would have it looked at. My jeep acts up too when it gets cold. Its lovely 0 degrees where I'm at

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Old 01-22-2011, 10:34 PM   #3
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Mine did a similar thing except it was more drastic. Fixed by cleaning and tightening loose battery terminals. It was fine in the summer though cause the metal expanded just right to tighten it up. The cold made it loosen up just enough
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Old 01-23-2011, 02:39 AM   #4
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My '91 did that just before the battery died.
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Old 01-23-2011, 08:26 AM   #5
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You didn't provide any information regarding the age of the battery and the cca. If it's over 3 yrs. old and doing that in cold weather; first check the connections. If it's still doing it I would install a new battery. I don't like getting stuck because of a bad battery.
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Old 01-25-2011, 03:35 PM   #6
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Thanks for the info. I'm going to try tightening up my connections tonight and see what happen.

@ kik - Good call, I should have provided that info in original post. Battery is 1 yr old & I can't remember cca but it's high. I have the warranty so will probably return this battery & get a new one if tightening connections doesn't change anything.
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MODS: 2.5" Rubicon Express lift, 1" lift greasable shackles, POR-15'd new frame, Chrysler 825 rear end w/355 gears and disk brake swap, solid front axle (no more vacuum!), herculined tub (interior & bottom), Dunlop Radial Mud Rover 32X11.5 R15 on black steel rims, custom hi lift jack hood mount, Ramsey 8K winch, and AEM Brute Force air intake system.

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Custom rear bumper in progress, Rock sliders on deck, and then front bumper...all fabricated by...ME!
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Old 11-18-2011, 05:46 AM   #7
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I was looking into an issue with my jeep (2004 TJ) suddenly displaying very low idle once warmed up. This became evident immediately after the battery was drained too low to start by leaving the lights on. Battery is original and about 8 years old now. Any advice on this would be appreciated...

That said, I was looking through the service manual and found something relative to this post. Voltage regulation is governed by a circuit in the PCM module. The Voltage regulation circuit uses the battery temperature sensor located under the battery on the battery tray to determine the charging voltage applied. The manual states, "System voltage will be higher at colder temperatures and is gradually reduced at warmer temperatures." This is consistent with what your gauges display and seems to indicate normal operation...
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Old 11-18-2011, 11:00 AM   #8
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[QUOTE=Mictrik;1754120]I was looking into an issue with my jeep (2004 TJ) suddenly displaying very low idle once warmed up. This became evident immediately after the battery was drained too low to start by leaving the lights on. Battery is original and about 8 years old now. Any advice on this would be appreciated...

I'm not sure about the low idle, but if you were lucky enough to get 8 yrs. out of a battery, which is still hard to believe, then you need to replace it yesterday.
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Old 11-18-2011, 07:03 PM   #9
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Change the battery, can't believe the battery lasted this long....it takes a certain amount of "minimum voltage" to run the engine, I think it may still be 11.5 volts...
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Old 11-21-2011, 12:57 PM   #10
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Quote:
Originally Posted by Garyk View Post
Change the battery, can't believe the battery lasted this long....it takes a certain amount of "minimum voltage" to run the engine, I think it may still be 11.5 volts...
I know, I never gave it much thought but the Jeep is a 2004 and it is the original Mopar 600 CCA battery. The jeep only has 59,000 miles on it, has been kept in a garage and has been extremely well maintained. This is why it has lasted so long (& luck). The low idle is due to lack of (not enough) exciter current at idle when the battery has been drained. I decided 8 years was enough and headed to Costco to pickup an Optima Blue top. The trip to Costco sufficiently charged the battery because by the time i got there idle was perfect and this was good news since they had no Optima's at all. After reading various posts I have decided to go with the Die hard Platinum 34M, meanwhile I placed my battery on a charger overnight and it again performing perfectly..???. as it passed a load test. The battery did supply power to the high beams & fogs for 40 minutes before it was drained low enough to click the starter. I am still going to replace it for winter but would like to find a better price than 219.00 for the DH platinum. I really think that price is a bit ridiculous.

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