How To Upgrade Alternator On Jeep XJ

An alternator upgrade can be a nifty performance hack for your Jeep Cherokee XJ. It can prolong the lifespan of the alternator, improve fuel economy, and lead to better battery performance. 

How to upgrade the alternator on Jeep XJ? That’s the question we will try to answer in today’s discussion. 

When To Upgrade Alternator On Jeep XJ?

In simplified terms, the battery provides energy for essential functions. The battery recoups the lost power from the alternator’s AC flow. When the alternator fails to keep up with the power demand, the battery loses more power and dies at one point. 

An underperforming battery can lead to a myriad of problems. The headlights might not be bright enough, the accessories might not function, and you might regularly struggle to start the vehicle. Getting an alternator with more capacity can alleviate all these issues.

How Much Do You Need To Spend For Upgrading Alternator On Jeep XJ?

The alternator itself will cost around $120-$150. You will also need an electrical cable to install the new alternator. The cable price would be similar to that of the alternator unit. Also, throw in $50 for equipment costs. Overall, your budget should be $350-$400.

The higher amperage you go for, the costlier this process gets. Most modern vehicles don’t need more than 160 amperes from the alternator. It should be enough for your Jeep XJ as well. Go for more powerful units if you are sure you will need more electricity to meet your accessory demands. 

How To Upgrade Alternator On Jeep XJ

Our first order of business will be to remove the stock alternator. Then, we will have to install the new one. You will need a new power cable since the old one will be incompatible with the new, high-capacity alternator. 

We will consider a 1999 Jeep Cherokee XJ for this tutorial. This particular model has a 90-amp stock alternator. Some older models had less alternator power, while many newer ones feature stronger stock alternators. We will install a 160-amp alternator to boost the performance of the 1999 Jeep XJ. 

Detach the faulty 90-amp alternator from the front of the engine and the aluminum brackets holding it in place. It has six groove pulleys, and the 160-amp alternator has 7. The other difference between these two is that the 160-amp alternator is a bit larger in frame size than the 90-amp one.

To fit the new alternator in the original brackets of the Jeep, we’ll have to make some adjustments to the brackets. If we try to fit the new alternator in the brackets, we can see that the brackets are coming in contact with the alternator and blocking it in some areas. So, to get clearance, we’ll have to trim a tiny amount of the aluminum brackets in these areas. 

The alternator’s positive wiring is the next thing we need to change. The electric wire needs to be changed. The green wire connecting to the fuse panel is around 6-8 gauge and has a fusible link. Its capacity is about 100-amp which is suitable for a 90-amp alternator.

But for the new 160-amp alternator, it’s not going to work. Because a 160-amp alternator can supply 180-amp output at full load, the stock chargeback wire will not be able to handle that flow. 

We can use a larger cable suitable for welding or batteries to solve this problem. You can use a 2/0 (two-aught) cable for better service. Along with this cable, you’ll need 3/8″ hole wire end copper lug terminal connectors and a heat-shrink tube to protect and cover the joints of the cable and the lugs.

If you can get a heat-shrink tube that has an adhesive lining and is heavy-duty, that’ll be helpful. But a light, the non-adhesive heat-shrink tube also works just fine. 

Now, take the new cable, and cut it just as we did the green cable. Then trim the insulation from the cable exposing the wires so that it fits in the lug terminal connector. Heat the lug up with a gas burner.

Once hot, get a soldering wire and melt it into the lug. Put the wire end of the cable in the lug while the solder is still hot, and then let it cool down. To attach the heat-shrink tube to the joint of the wires and lug, cut a small portion of the tube and put the cable through it.

Place the heat-shrink tube piece on the joint and heat it with a heat gun. This process will shrink the tube and hold it on the joint firmly. Do the same thing for the other end of the cable. 

We’ll use a 250-amp fuse to replace the fusible link and mount it with a fuse holder between the battery and the car. Alternatively, you can use a 200-amp fuse to establish a connection with the fuse panel. 

After that, replace the new alternator’s pulley with the 90-amp alternator pulley. Because it’s smaller than the new one and has six ribs, it’ll fit the available and make it spin faster at idle. And so, its amp output will be higher.

Finally, let’s put the alternator in the car mounted with the brackets, connect the battery, all the wires, and the belt correctly, and start the engine.

Final Words 

We hope reading this article has helped you to learn how to upgrade the alternator on your Jeep XJ. The alternator upgrade is essential to modernizing your Jeep XJ. With more power fueled by your new alternator, you can now make further upgrades without worrying about power constraints.