Possible battery/electrical problem

I have a 2000 XJ 4.0 with 150k miles. The electrical accessories I have include upgraded H4 headlights with harness, (2) 130 watt KC lights wired in with high beams, stock fog lights, and heated seats.

My current battery is an Autozone Duralast Gold with 800 CCA, it is about 1 year old. This replaced my Optima yellow top after it failed.

I have recently added Jeepers and Creepers battery cables, 5-90's alternator cable with 200A ANL fuse, and a 150 amp alternator. The alt is a stock sized case rebuilt to handle 150A.

Ever since this winter hit, my Jeep turns over slow. I thought it might be the starter, but the Jeep only cranks slow on a cold start. If I drive somewhere, then park it for an hour or two and come back it will crank right up. If I'm driving and turn my high beams on (with the KCs) everything is fine. If I turn the high beams (and KCs) on while sitting idle at a stop sign, the lights will dim and the volt gauge will drop to 12 volts. Turn the high beams off and everything goes back to normal at idle. If my electric fan comes on with just the head lights on, the battery gauge will dip to 12 volts again.

I never noticed this with my Optima battery and stock battery cables. Is this an electrical system problem or just a crappy battery? I tested the battery with a load tester and it tested OK, but that was also after driving it for a bit. Battery terminals have been replaced with brass terminals.

I'm stumped. Any help is greatly appreciated.

Honestly, it sounds like the alternator isn't putting out the amperage, especially at lower RPM. Will the voltage go up if you bring the RPMs to 2500 or so?

I had a "high output" alternator that would only put out decent amperage above 3000 RPM. Played hell with the electric fans at the time.

David Bricker / SYR

Yes, if I bring the engine up to 1000 RPM everything returns to normal. I don't remember how my stock alternator functioned with this load, since the alternator that the new 150A replaced was a Duralast rebuilt one that only functioned so-so anyway. I guess my question is would this load be way too much for a stock alternator to handle at idle, so much so that it dips the volt gauge to 12 volts?

My buddy has a 2000 XJ with the same head light upgrade, and some 100 watt Hella lights. He has the stock 15 year old alternator and his doesn't have the same problem.

One thing that strikes me is how this problem definitely worsened when I went from my Autozone rebuilt Alt to the new 150A alt and bigger cable. The 150A alt was swapped in 3 days ago, and the problem has gotten much worse immediately after the swap. I'm thinking my "high amp" alternator is only producing power at higher RPM, and my Duralast junk was only mediocre to begin with. I never had these sort of issues with the stock factory alternator (before the bearing started making noise) and the stock crappy battery cables.

I'll see if I can post a video later on tonight to show what it is doing.

Here is a video:

https://www.youtube.com/watch?v=v-Buiq3x5mw

Alternators typically don't put out much amperage at idle. 40 amps if you're lucky, 20-30 is more realistic. I have no idea what your "high output" alternator actually is, so I'm going to guess that they probably just swapped the stator out or reconnected it from Wye windings to Delta. Not sure if I remember it correctly or not, but IIRC the delta connected windings will put out more, though only at higher rpm....which is the same as what happens when someone swaps in a higher output stator. You'll probably have to get into a full custom alternator with a rewound rotor and stator to get much more output at idle.

The other possibility is that the pulley diameter on the "new" alternator is a different size. A new pulley would run about $20, but some are not easy to change. The problem with swapping pulleys is that you need to do some math and make sure that you're not going to be spinning the alternator beyond what it's designed for. Denso doesn't publish any specs at all on their alternators(according to what I read anyway, couldn't find anything on their site), so I'd have a look at whatever the delco replacement is and get the info from the delco-remy website. I *think* they also list what the pulley diameter should be for a particular application, but I may be wrong.

Here's something I pulled up on the delco site for a 2000 xj with a 4.0 when searching for a replacement alternator. https://www1.remyinc.com/webpictures/techtips/TT-657.pdf
http://catalog.remyinc.com/Product/...&model=Cherokee&engine=4.0+Liter+L6+-+242+CID

Thanks for the info!

I have an update today, as I have done some testing.

I tested the battery with a load tester, after the battery sat overnight and the Jeep was stone cold. I noticed within the last month that the Jeep will turn over slow after sitting over night, but if I restart it hot (after stopping at a store or something) it will fire right up like normal.

Here is the voltage before doing the load test, this is an 800 CCA battery, and it reads right around 12.5 volts.



Here is with the battery under load:




Here is what the voltage of the battery is after completing the test, slightly lower.




This battery was fully charged two days ago on a 2 amp charger.


I'm wondering if the problem is my battery can't handle the load at idle from the high beams/KC lights or the fan. I swapped out my 150A alternator for a stock junkyard unit today just to see if it did anything. The junkyard unit appears to be a Napa rebuild from 2007 according to the sticker. It seemed to help a little bit at idle, but I still had a pretty large voltage drop when I turned on the high beams or the fan.

It looks like your battery is fine. I would check voltage at the battery with the engine running with a good multimeter. Then turn on your headlights and check again.

My guess is that you're drawing well in excess of what the alternator can produce at idle. The two KC lights alone are drawing almost 22 amps. Your headlights probably draw about the same. That's 40+ amps for just two accessories. Add in your electric fan for another 10 amps or so, plus any other electric device you have on. Anything above what the alternator can produce has to come from somewhere, which is the battery. That's why your voltage is dropping.

I'm interested in this as well. I've been having the same symptoms as the OP with a similar setup - 5-90 mains cables with a 150A ANL fuse and a brand new Interstate battery (800CCA).
For the past month or so my XJ has been slow (~3-5 seconds to start). I took it to Advance Auto and they tested for a bad battery and alternator - my battery was around 500CCA. Now, even after the new battery, it's still slow to turn over. What makes it more frustrating is that yesterday morning I was sitting at a stop light and the Jeep just shut off on me - lights stayed on though. I just put it in N and it started right up.

Any idea on what these electrical gremlins might be? Maybe a bad CPS? Oh, I have a 2000, AW4 w/ 116,000 miles

I don't have 5-90's cables, so I have to ask: Are they identical to factory cables other than the fuse and cable size? In other words, do they attach to the same points, in the same order? Also, are the lugs on the cable crimped or crimped and soldered? Crimped connections are mainly mechanical. Crimped and soldered are mechanical and electrical connections.

I'm asking because the PCM is what regulates voltage on '91 up XJ's. If the PCM draws power from the main power distribution center in the engine compartment(example only, I haven't double checked) and the connections between the starter/battery/alternator/PDC have changed, then the PCM might not be getting accurate readings on system voltage. If that's the case, it will not be able to properly regulate the alternator's output and you may have an under or over voltage condition at the PCM. This could cause the PCM to shut down or errors with sensor readings. Poor connections could cause similar issues.

I believe I've read that most chrysler products don't charge at ~14 volts like gm and ford. Instead, they usually are set at around 13.5. If that's the case(which would be pretty dumb IMO), then XJ's left the factory with a handicapped charging system.

If you haven't already done so, I'd suggest pulling the starter, taking it apart and giving it a bath in electrical motor cleaner(try to keep it out of the bearings though). Check the brushes for wear and polish the copper surfaces of the armature/commutator with gray scotchbrite(lowes or home depot will have it with the sandpaper). I posted a thread a while back in the OEM section with a link to where to buy parts like brushes for the starter. Only reason I'm telling you to check this is because I had intermittent cranking issues with my '00 due to my starter being full of oil and road grime. I didn't know, but figured out, that my oil filter adapter was leaking and causing the problem. The oil attracted all the grime which wore the brushes out in addition to creating poor contact between the brushes and the commutator.

Taken directly from 5-90's site (http://www.kelleyswip.com/electric.html):
He uses "1AWG or 4AWG welding cable"....."All connections are pressure-crimped, packed with corrosion inhibitor, and sealed twice - first with vinyl terminal tape, then with polyolefin heat shrink tubing. This makes a connection that should never be contaminated or work loose over the life of the vehicle."
Great product and I highly recommend them.

Now that you mention it, I have seen oil on my starter. I've been meaning to get that cleaned up. I'm for sure going to change out those O-ring adapters on my next oil change now. I don't feel too comfortable taking apart my starter and cleaning it - I can do most things on my Jeep myself, but with anything electrical, I have some bad mojo going on. Probably best to just replace it - it is the original starter.

Replacement brushes with the brush holder assembly will cost you all of $17.46 and shipping. Brushes alone are roughly $6 for both sets, plus shipping. Other than the solenoid, there isn't much else to go wrong. There is something of a tech writeup on servicing the starter somewhere on this site. It's easy, shouldn't take more than an hour, including the time spent taking it off the jeep.

As far as the cables go... I didn't know you could crimp anything without pressure. Welding cable is superior to battery cable in pretty much any way you can imagine. They would be better if they were soldered as well though. More surface area contacting the lug, and an actual bond between the metals versus just mechanical pressure.

machinisttx said:

Replacement brushes with the brush holder assembly will cost you all of $17.46 and shipping. Brushes alone are roughly $6 for both sets, plus shipping. Other than the solenoid, there isn't much else to go wrong. There is something of a tech writeup on servicing the starter somewhere on this site. It's easy, shouldn't take more than an hour, including the time spent taking it off the jeep.

Click to expand...

Ok so I found a few write-ups on how to rebuild the starter, seems pretty straightforward. I've searched for quite sometime but I'm not having any luck finding the solenoid or replacement brushes. Could you please tell me where to find them?

I thought I had linked the site here, my bad.

This is the brush holder with brushes. http://www.aspwholesale.com/index.php?search%5Bkeywords%5D=69-8318&_a=category

If you just want the brushes: http://www.aspwholesale.com/index.php?search[keywords]=68-8328&_a=category and http://www.aspwholesale.com/index.php?search[keywords]=68-8330&_a=category

Here's the solenoid. http://www.aspwholesale.com/index.php?search[keywords]=66-8384&_a=category

Here is the the plug in terminal that goes on the solenoid if you want some extras. http://www.aspwholesale.com/index.php?search[keywords]=76-83552&_a=category

machinisttx said:

I thought I had linked the site here, my bad.

This is the brush holder with brushes. http://www.aspwholesale.com/index.php?search[keywords]=69-8318&_a=category

If you just want the brushes: http://www.aspwholesale.com/index.php?search[keywords]=68-8328&_a=category and http://www.aspwholesale.com/index.php?search[keywords]=68-8330&_a=category

Here's the solenoid. http://www.aspwholesale.com/index.php?search[keywords]=66-8384&_a=category

Here is the the plug in terminal that goes on the solenoid if you want some extras. http://www.aspwholesale.com/index.php?search[keywords]=76-83552&_a=category

Click to expand...

Fantastic - thanks! I'm going this route instead of buy a new starter.