Automotive High-output alternators, used in police and emergency vehicles, have high-quality components, close internal tolerances, improved cooling characteristics, higher output at lower engine rpm, and altered voltage regulation. The 100 amp alternators will typically charge batteries four to five times faster than a 35 to 55 amp standard alternator Alternators, named for the alternating current (AC) they initially produce, actually have internal rectifying diodes that change their electrical output from alternating to direct current (DC), making it suitable for battery charging. High-output alternators are classified by rated output and case size. When comparing these alternators, there are several important questions you should ask, the first probably being: Will it fit. Some high-output alternators replace OEM equipment bolt for bolt. If this isn't the case, you'll have to construct custom brackets for your high-output alternator; this is a very involved and time consuming task. Some high-output alternators have internal regulation, while some high-output alternators have external regulation. I recommend using external regulation, high-output alternators if possible, since this type of high-output alternator makes it easier to adjust the electrical system's voltage. The most important specification to query is the high-output alternators current rating. Make sure all ratings are for hot high-output alternators; output current usually drops as the high-output alternator heats up to its normal working temperature. Find out what the output current is at both idle rpm and highway rpm. When comparing high-output alternators in this manner, make sure both units have pulleys of the same size and thus the same rotor speed.

Most stock alternators produce only about 60 amps maximum. Of this, about half is used to run the car itself. So this leaves you with about 30 amps for your system, 94 amps less than the 124 you need. Where will the other 94 amps come from. The battery will try to supply it, but it will be able to do so only for short periods before the voltage drops to an insufficient level. Your system will not be able to play at its full potential for any significant length of time. There are several things you can do to increase the performance of your electrical system. First, you can replace the stock alternator with a high-output alternator, the single most important modification you can make.

High-output alternators are classified by rated output and case size.

• Small case models, which are direct replacements for almost all standard alternators, are the least expensive and range from about 75 amp to 150 amp rated output.
• Large-case models, slightly bigger in diameter, are quite a bit more expensive and range from about 160 amp to over 200 amp output.
• High-output alternators can make a dramatic difference in battery charging performance.
• The 100 amp high-output alternators will typically charge batteries four to five times faster
• High-output alternators have internal regulation.
• Some high-output alternators have external regulation.