Buying a new high output alternator doesn’t have to be any more complicated than purchasing a regular alternator, but there are a handful of issues that can turn into roadblocks or headaches. The most important thing to remember is that unless you’re replacing a factory high output alternator with an identical unit, there may be fit issues.
High amp alternators tend to be big, which means they generate a lot of heat, and some of the more powerful units even require external cooling. In that same vein, it’s also important to verify that there aren’t any belt or pulley issues with an alternator before it is purchased and installed. Of course, it’s almost impossible to overstress the importance of verifying that an alternator is capable of putting out enough amperage. An overworked alternator will tend to fail prematurely, and some situations may even call for a dual alternator setup.
The Importance of Size and Fit
Unless you’re replacing a factory high output alternator with an OEM or remanufactured unit of the exact same design, you may end up dealing with size and fit issues. This is especially true if you’re replacing a standard alternator with a high output unit due to the fact that high amp alternators can be quite large. In fact, you should typically shy away from any so-called high output alternator that is essentially just a rewound standard output factory unit. Many of these units fail to produce as much power as they are supposed to due to size constraints and the physical limitations of the original casing.
The most powerful high output alternators actually require external cooling, which is another important factor to consider. Some of these units are even water-cooled, and that can complicate matters if the vehicle isn’t already plumbed to provide coolant to the alternator.
Belt Size and Acceptable Loads
A high amp alternator can put a lot of stress on a drive belt. In fact, a typical high output alternator has an output to horsepower load ratio of 25:1. That means a 300 A alternator will act as a 12 horsepower load when it is running full out. Since there are some pretty hard limitations on exactly how much stress these belts can take, it’s important to make sure that your alternator and crank pulleys are up to the task. As a general rule of thumb, any alternator that puts out more than 110 A requires either a serpentine belt or dual v-belts.
High Output Alternator Overdrive Pulleys
In order to work properly, some high output alternators require overdrive pulleys. This is an important thing to know about an alternator before you buy it because the overdrive pulley may be smaller in diameter than your original pulley. If that’s the case, and you end up having to swap the pulleys for any reason, the new alternator typically won’t provide enough amperage at idle speeds. That makes it even more important to verify that the replacement unit will fit and line up properly before you purchase or install it.
If you have any questions about selecting the right high output alternator for your requirements, contact us today.