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Checked several times and IOD is .034. New battery. When driving voltage is between 14.5 and 13.5, depending on temperature. After shut down voltage drops about 12.4 V after a couple hours. The longer it sits the lower the voltage – in 48 hours down to 12.20 V. According to battery info 12.24 volts equals a 50% charge. Jeep starts fine.
Is this normal?
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Are you sure the connection is good, area around it is clean, belt and tension is nice and tight, alternator is charging correctly, battery itself is good, or you just have a small leak?
My 99 4.0 WJ eats batteries for breakfast. My other two WJ’s don’t, and this is what my theory is. I believe what happens is there is a circuit that wakes up at random intervals that is drawing it down. So unless you happen to be standing there testing for parasitic draw when it comes on, everything appears normal. Pulling the HVAC fuse seemed to make my battery hold up better to the car not being driven for a few days. My 99 has AZC, the 00 and 04 have the manual/vacuum actuated HVAC. I chalked this up to my known faulty AZC blend doors. The AZC will periodically try to reset or calibrate the doors I think, and since the gears are all stripped out it just runs the little motor and never sees it do anything so it keeps trying every once in a while. Just my experience…
I suspect the battery. I would recommend you take it somewhere to be load tested. Static battery voltage on a good battery should be 12.6 or above. Also, you might check the battery while it’s disconnected from the vehicle. If the voltage does not drop then, you might have a parasitic draw on the system. For that, this video might be useful. However, have the battery checked first. If you don’t have a good battery, you can’t test the rest of the system.
FWIW my 2000 4.0 was sitting at 11.8v just now after sitting for 18 hours. Although it cranked a tad slow it fired right up. For being 17*F outside now I’m not too worried, the battery is only a month or two old. Per my voltage gauge and multimeter between 13.5-14.5 is what both my 4.0’s always run at. I mention the thing above about the AZC because anytime my 99 sits for more than 2-3 days it’s completely dead except when the battery is brand new.
Yup like Eric suggested, take it to an auto parts store to get the battery tested for free (if you do not have a load tester). If it is still good you should do a parasitic draw test… Sometimes diodes in the alternator go bad and have a parasitic draw and kill a battery in short time….
Not to insult your intelligence, but a battery voltage test is only half a test, the battery needs to be load tested with a special tool to tell you the true condition of the battery….
-Karl
Battery voltage is not a reliable indicator of anything. Also your voltmeter could be off by a percent or two. The real test is to turn on the headlights. A good battery will run the headlights for at least an hour. Wait until the headlights are getting a little yellow or the battery voltage is down to 10 volts. If that time is less than half an hour, the battery was either low in charge, or just plain unable to hold much of a charge. Then start up the engine. If the alternator is working the lights should brighten up and the battery voltage should go up several volts.
I had the battery load tested twice and it checks out better than it is rated at. How can the diodes be checked? Can an amp meter be connected between the alternator and the battery to see if current is flowing when the vehicle is off?
The “load tests” are not terribly dependable. Batteries can have good performance for a short load test, but they can droop under real conditions. A better test is with the headlights.
[quote=”georgeda” post=86389]How can the diodes be checked? [/quote]
Save ripping it apart and looking you can’t really “for certain” see how all of them are. A decent gauge of their condition however is measuring the AC bleed-over, if this is fairly high, it’s a good bet you’ve toasted a couple or more and it’s not outputting much amperage wise.
http://assets.fluke.com/appnotes/automotive/beatbook.pdf (view page 3 figure 4, “ripple”, to test this)Renting a cheap ammeter (clamp-over style, not inline) to measure the amperage output (off the B+ alternator line to the battery) after draining the battery a bit is also an option.
One last simple test, do at your own risk of course. Loosen the negative terminal, start car, after the 30seconds or so it takes for the ECU to tell the alternator to start putting out power, yank the negative terminal. If the car dies/stalls, then the alternator is likely bad as it “should” have enough to keep the car and moderate accessories going after it’s running without the battery.
[quote=”georgeda” post=86389]Can an amp meter be connected between the alternator and the battery to see if current is flowing when the vehicle is off?[/quote]
Yes, if you’re thinking parasitic draw, then just go over Eric’s Parasitic draw test vid, remembering of course the limitations of whatever multimeter you are using. Most can only handle 10A (amps) max. So you will need to usually jam the door switch with something and wait 20mins after you’ve hooked it up in-line to the negative terminal.What you really need is a full charging system test, some shop has the diagnostic tester, they test the alternator, battery, and the starter at the same time, it’s a lot more accurate then individual testing, i do this all the time.
I would have the complete battery and charging system checked by someone reputable before coming to any conclusions.
I find that in a very cold climate and drive a lot of short trips with the heater, wipers, rear defroster on that the static battery volts are always a little lower than ideal. If the alternator output amps are higher than the load on the battery than your jeep is operating normally. I would expect to see 13 to 14 volts at the battery at about 1500 rpm with all loads turned on.
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