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Crown Vic Alternator?

BADaXJ

NAXJA Forum User
Location
Maine
I just finished up running all the wiring for my winch tonight and decided to try it out. My alternator was replaced when i bought the jeep about two years ago. to sum it up, i was pretty disappointed with the performance of my stock alternator. i didn't even run the winch that hard and it drained my red top pretty quick. and it even triggered the check guages light
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i was keeping a close eye on it because i knew that when my battery lost juice, it was going to happen fast. didnt anticipate it that quick though and i'm hoping my battery voltage didn't drop too far below 10v and put a serious hurtin' on my battery.
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after that first experience, i decided that with all the crap wired up on my rig, it was time for a serious upgrade. i dont have cash for a mean green but i've read about the grand cherokee swap. i located a 136 amp GC unit at a local salvage yard for $40. seems like a good deal but is 46 amps difference going to justify the cost/work? i remember hearing from one if my buddies that a crown vic alternator was pretty much direct bolt in. anyone ever hear anything about that?
 
Did you run your winch at engine idle? Alternators will usually only give you 40-50% of max output at idle (at best...) and that can present as other issues.

You start getting the potential for full output up around 1200 crankshaft RPM or so (given that most alternators are about 4:1 on the pully ratio, that comes up around 4500-5000rpm at the alternator...) and that will help you much. That's why the "extended idle" switch can be found in an awful lot of emergency vehicles - to bring the crankshaft speed up to where the alternator can make enough electricity to keep things supplied...

But yes, you'll probably note something better with the ZJ unit - same conditions apply, tho. You may want to search up the "Extended Idle" mod here and see if it can apply to you as well (or just start thinking about a hand throttle with a friction lock. Or a secondary deep-cycle battery.)
 
Whats the amperage difference of a GC alt compared to a crown vic alt?

May depend on the year of your XJ to see if it will work or not...

Either way the Alt. would be an upgrade but to get the full benefit you need to idle higher...

As pretty much always, going with what 5-90 said is a good choice, even if its not right its always a good starting point ...

Side note, red XJ that I usually see at the garage next to Subway? Only one Ive seen lately with a winch.
 
Sounds to me like your Red Top may not be in perfect condition. I've seen guys winch tons with a stock alternator with no problems. Issues are much more frequent with the condition of the battery than with the output of the alternator.

But, you haven't told us exactly how you used the winch.
 
Goatman said:
Sounds to me like your Red Top may not be in perfect condition. I've seen guys winch tons with a stock alternator with no problems. Issues are much more frequent with the condition of the battery than with the output of the alternator.

But, you haven't told us exactly how you used the winch.

I agree with Goatman. Your battery may be on its way out. The GC alternator is a great upgrade. The AMPS out of that ting is way higher than the stock XJ at idle. I did that upgrade when I installled the eletric cooling fans. The stock XJ alternator could not keep the fans and the AC running at idle. I would say make the switch. It will make you happy.
 
The GC/Durango alt. + the extended idle switch will definately take care of it. I used my winch the other day for some yardwork, flipped the ext. idle switch, and my stock alt. had no problem handling the load. Granted, I wasn't doing a full on stuck pull, but it was pulling a decent amount.
 
be careful if you kill drain that red top more than a few times it does some serious damage and the battery will be pretty much useless yellow top is the way to go you can drain it as many times as you want without hurting it.
 
Not sure about those red tops, they're on sale now up here in Walmart for 139 CD. I think the blue tops are the only way to go anymore.
 
The Crown Vic. alt puts out about 130-135 amps. For the price diff. I would go with the yellow top, at least if you drain it few times it won't become junk.
 
I have a 136amp Dodge 1/2ton in my rig. Winch, 2 batteries, lights and other accesories like small fridge and stereo I have no issues. CHarges well. PRobably could still go bigger, but I have never drained a battery. And I just use 2 CarQuest 700CCA Batteries.
 
i was running about 1500 rpm, i have a hand throttle so thats not the issue. the battery is less than a year old too and it's never been discharged below 12 volts. i've never had any electrical power problems until now. the battery has worked great for me so far and i usually run just a tad over 14v at idle. lights don't dim when i turn on accessories or anything and the alt is only a couple years old so i dont think thats the issue either. it's never been swamped or anything either and i have a front skid plus a splash shield so i doubt it has been compromised. i was just messing around really, winching up a hill but not for long. i did hit the brakes to put a load on it and see what happened. thats when the meter dropped off and the check guages light came on. how long should i be able to do hard pulls without letting off? the wotor wasn't in the best shape but i cleaned it up best i could. maybe its shorting/ overdrawing? used it the next day to pull my new comanche onto the trailer and it worked fine, didn't seem to bother the battery much. i can't afford it right now and i don't have the time to swap... i need to do some other things first. i think maybe buy this summer though i'll plan on the GC swap. i think the 5.9 limited had a 160 amp alternator.
 
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