Bolstering Your Electrical System with a High-Amp Alternator
Okay, youve spent all your hard earned cash on a sophisticated mobile electronics system with big 15 woofers, multiple amps, video screens, a splash of neonthe whole nine yards. Now youve got a sound system that leaves your ears ringing, your eyes dazzled, and your head spinning. Thats good.
If youre not careful, though, it just may leave your vehicles electrical system smoking, melting, and frying, too. And thats not good.
The fact is, a typical OE electrical system doesnt have the alternator capacity to handle the power demands of high power aftermarket electronics. While your factory electrical system has some extra capacity for small accessories, the extra amp draw created by a high power electronics system can cause a stock electrical system to literally melt from the inside out. Unfortunately, most people dont realize theres a problem until its too late.
Luckily, the whole mess can be avoided by making a simple alternator upgrade when you build your mobile A/V system. Well take you through the whole processhow to determine the need for an alternator upgrade, how to find the right size alternator, and tips for getting the most from your alternator.
Do You Need a High Amp Alternator?
If youve spent thousands of dollars on audio/video components for your vehicle, chances are you need to upgrade your alternator. The reasons are quite simple when you understand the definition of amperage.
Amperage is the maximum capacity or maximum volume of electricity that your alternator is capable of producing. If your vehicles electrical load exceeds the amperage or maximum capacityof your alternator, youre asking for trouble.
Most factory alternators are rated at 65 to 100 amps. Those amps must handle the electrical load of your entire vehiclethings like headlights, gauges, fuel pumps, transmission, air conditioning, and much more. Once the alternator applies its power to all these items, there is not a lot of amperage left over. And although many alternators supply 10% to 15% more power to handle additional, non-factory accessories, they simply cant power a complex mobile A/V system.
For example, lets say youre running a 65 amp alternator on a vehicle that draws 60 amps, and youre thinking of adding a 500 watt stereo system. A typical 500 watt stereo system draws at least 60 amps. To attempt to power all your factory electrical components and your new stereo systema 120 amp drawyour alternator will have to run at 100% capacity (and draw reserve from your battery, too) with no cool down time. As a result, the alternator will have a drastically reduced life span and may even melt or burn up internally.
If youre looking for hard evidence that you need to upgrade your alternator before you go out and spend the money, just take a look at your voltmeter. When you are drawing reserve power from your battery, the voltmeter will read below 12.7 VDC. If your voltmeter spends a lot of time below the 12.7 VDC figure, you are surpassing the maximum capacity of your alternator and will need to upgrade it.
Choosing the Right Alternator for Your Vehicle
Selecting the right alternator to meet your vehicles electrical needs comes down to figuring out your vehicles total amperage requirements. To determine the amperage requirements of your vehicle, you need to calculate the total electrical load of your vehicle.
The most accurate way to figure electrical load is to use an ammeter. With your engine off and the battery in a good state of charge, connect an ammeter in series with the grounded terminal of the battery and the ground cable. Then, switch each individual electrical component on and off one at a time and add up the ammeter readings of each. Your alternator output should be 50% more than the sum of all the individual readings.
If you dont have an ammeter, you can estimate electrical load by checking the fuses on the accessory devices. The figure on each fuse will be slightly larger than the highest amp draw of each component but should give you a general idea of the electrical load of your car or truck.
There are a couple of things to keep in mind as you are measuring for electrical load. First, you can never have too much amperage. Again, amperage is defined as the total electrical capacity of your alternator, and it is impossible to have too much electrical capacity.
Secondly, you can actually gain back horsepower by adding a higher amp alternator. True, most alternators are only about 85% efficient (some power is lost in the form of heat and wind resistance from the cooling fins). But upgrading to a higher amp alternator can help you gain back significant horsepower by allowing your electrical system to run at maximum voltage. In most cases, youll actually see a slight gain in horsepower!
Getting the Most From Your High Amp Alternator
Installation of your new high amp alternator will vary depending on the brand and style. For example, some alternators like the Powermaster will work with your stock brackets, wiring, and belts and, in many cases, will accept stock pulleys. Other alternators will require some modifications. You should always follow the installation instructions that come with the alternator. However, there are a couple of ways you can assure optimum performance no matter what brand of alternator you choose.
First, make sure you are using the proper size charge wire. The charge wire is the wire that the amperage from the alternator flows down to the battery and the rest of the system. While the existing wire may be compatible with your stock alternator, it is likely to be too small for the extra capacity of a high amp alternator and may restrict the flow of electricity.
Next, closely inspect your stock belts before installing a high amp alternator. In most cases, high amp alternators come with a smaller pulley than stock to overdrive the system by 16%. The slightly heavier load of an overdriven alternator will cause added stress to your belt, so its extremely important that your belt and belt tensioner (if equipped) be in excellent shape.
Finally, if you are strapped for space, many alternators can be run in reverse (with the pulley side toward the driver). While the alternator will still charge properly, cooling efficiency will be reduced and life span of the alternator may be shortened.
Remember, high power mobile electronics systems should overload your senses, not your alternator. The next time you plan to add some wattage to your stereo system, consider adding some amperage first by upgrading your alternator.
too flashy for my taste.... and reminds me of a very bad movie... 💡
Nice looking truck though. I always like the 2door S-10 blazers for some reason. The ZR2's look real good too. You hardly ever see the 2 doors. Hey, if you use the lights to win awards, then more power too ya. As long as you don't drive around with them on. Just don't get tooo ricey 
