Snowdoggie (Forum Supporter)
Snowdoggie (Forum Supporter) SuperDork
8/12/22 9:52 a.m.

I am considering a higher output alternator to power a winch, lights and various other accessories on my XJ Cherokee. I know I am increasing the the amps going into the electrical system. Do I have to rewire part of my electrical system to handle the increased current? If so, what do I have to rewire? Are there other components I need to replace? Is adding a higher output alternator even a good idea, or will I fry my wiring? I know a lot of car stereo guys are doing it. I know police cars and ambulances have higher output alternators.

matthewmcl Dork
8/12/22 9:58 a.m.

The only wire that needs to get bigger is the charging wire from the alternator to the battery. The ground is already stout enough for the starter. Your battery runs the winch, really, but having capacity in the alternator helps keep the alternator cool as it recharges the battery.

jgrewe HalfDork
8/12/22 10:16 a.m.

I put a Durango alternator with an external voltage regulator on my XJ to feed a winch. Its also nice to keep the volts up over 13.7 no matter what I turn on.

I think I used 6ga wire to the battery.

Snowdoggie (Forum Supporter)
Snowdoggie (Forum Supporter) SuperDork
8/12/22 10:35 a.m.
matthewmcl said:

The only wire that needs to get bigger is the charging wire from the alternator to the battery. The ground is already stout enough for the starter. Your battery runs the winch, really, but having capacity in the alternator helps keep the alternator cool as it recharges the battery.

I am also thinking of adding a second battery if that would help.

jgrewe HalfDork
8/12/22 11:06 a.m.

In reply to Snowdoggie (Forum Supporter) :

I could watch the volts drop on my XJ as I turned on lights, AC blower, wipers etc until it would get to about 11V. The alternator checked out fine, it was the voltage regulator in the ECU.

I've run my winch with lights on and the Jeep off quite a few times on the single battery. Unless you are going to make a habit of it I don't think an extra battery is worth the weight. If you are going to run a 120V converter for that kind of power it would be though.

kb58 SuperDork
8/12/22 11:22 a.m.

The battery is only there for starting the car. Once it's started, the alternator runs everything, so you might want to guess the load imposed by each load, add them up, and size the wire appropriately.

matthewmcl Dork
8/12/22 12:36 p.m.

I forgot about the regulator in the ecu. Going to an alternator with an internal would be worth the trouble for nothing more than that.

californiamilleghia UltraDork
8/12/22 12:44 p.m.

I have seen the  120 amp small alternator that I think come off a forklift ,

Are they any good for everyday use , I was thinking of one for an off-road VW with a bank of driving lights on the roof , the lights would only be used a little , mostly  for show but need to light up !

Is there a better brand ? And best place to buy ?


kb58 SuperDork
8/12/22 1:01 p.m.

Price-wise, it's a good idea to adapt something off the shelf that's already out there. Buying a custom modified (rewound) alternator is great until it breaks in the middle of nowhere. For my one-off car, I added up all the loads that might be on at the same time, and chose a 1986-2004 GM CS-130D unit, widely used on Chevy pickups. Plenty of current and available everywhere, you just may have to modify the mounts and possibly the pulley.


jgrewe HalfDork
8/12/22 3:54 p.m.

Do a quick search to confirm my memory but I used a 160amp off an '01 Durango. It bolts to the stock bracket and has the correct spacing for the belt. I think I used the pulley off the old alt though. You will need to grind about 1/8" off a couple spots on the bracket.

There are a few places selling wiring kits to do the swap. They come with the adjustable external regulator and a resister to fool the ecu so the idiot light doesn't come on.

edit: just saw it wasn't the OP asking about where to find a good alt, I'll leave th info because it pertains to the Jeep question

buzzboy SuperDork
8/12/22 5:02 p.m.

In for the info. My XJ charges at only 13.25 under full load. Was thinking about the alternator upgrade as well.

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
8/15/22 4:21 p.m.

Friendly word of caution.  Re-winding an alternator for more amperage can be OK, but usually it's not. You can take a 10si case that was originally 30 amps and re-build it to 100 amps if you want, but it will last until the first time it tries to make 50amps.  The guts of any given case can only take so many amps.

re-wound alternators are for stereos where they only see 1-2 seconds of high amperage when the amps call for it.  Make sure that the case you are using already has been tested at the continuous amperages you're using.

I had a 12si case rebuilt for 100 amps.  I let the battery go dead so I got a jump start and hit the road.  The alternator lasted 2 miles.  It started pumping out 100 amps and cooked itself in very short order.  Of course, dumb-ass me diagnosed it by laying my hand on the alternator and had to go to the emergency room.

Instead, with the millions of applications out there which are all supplied by about 3 manufacturers, there is a better case that already comes with the amperage you need.  I found a CS130-style alternator at 125A that was a direct bolt-in on a 1967 Pontiac, and it was a factory application that I got from Rock Auto from something like a mid 90s Olds.  I strongly suggest you find a better alternator instead of just souping up what you have.  Keep in mind that many times the only thing separating the Delco alternator in your Jeep from one that's in a Sonoma is the clocking of the case.  If you order part number [insert jeep part number] and also order PN [insert Sonoma part number], they might be 100% identical except that the front and rear of the case were assembled 90 degrees rotated so it lines up with the different mounts.  The chances that there is an existing CS130 out there that will bolt in are about 1 in 1

VolvoHeretic GRM+ Memberand Reader
8/16/22 1:02 a.m.

After the Motorola alternator in my B30 Volvo 1800e died in the middle of nowhere western US, while looking through the pile of alternators at the local junkyard, I discovered that if I cut about 3/4" off of the back of the lower pivot mounting boss and drilled it out to 9/16", a Delco 12SI would bolt up to the motor. Unfortunately, it's low amperage output can't keep up with the electric fuel pump and twin electric fans. I am thinking of putting this brand new hybrid Delco unit in but I am not sure if it will fit since the 12SI barely did. AC130-HD160 - Hybrid CS130/AD237/AD244 Series Alternator, 160 Amp, Heavy Duty Rectifier, Standard Regulator, Replaces 10DN, 10Si, 12Si

I even made a comparison scale drawing but still can't tell.

Oops, my bad, I didn't notice that you all are talking about the CS130D. Never mind. 

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