Xantrex Technology 3000 Charging With an Engine Alternator, Using a Standard Vehicle Alternator

Alternators and Charging Systems

Charging With an Engine Alternator

Read the following information to determine whether your vehicle’s standard alternator will be adequate by itself, whether you should install an alternator controller, or whether you need a high-output alternator.

Using a Standard Vehicle Alternator

A typical engine alternator (12 V) may not be able to meet the requirements outlined above if your system uses large capacity batteries. Alternators are typically rated for the current they can deliver when they are cold. When in use, alternators heat up, and their output current capability drops by as much as 25%. Therefore, standard alternators with ratings of 40–105 A only deliver a maximum of 30–80 A in actual use and deliver even less as battery voltage rises. Many alternators cannot produce more than 13.6 V when they are hot. As a result, a standard alternator may not be able to charge a large battery quickly and completely.

Two solutions are to install an alternator controller or to install a high- output alternator.

Using an Alternator Controller

If your regular alternator is inadequate, you can install an alternator controller that bypasses the voltage regulator and boosts the alternator’s output voltage during charging. This will increase the alternator’s charging rate at higher battery voltages and ensure more rapid and complete charging.

Using a High-Output Alternator

Heavy-duty alternators rated from 100–140 A can replace standard alternators and produce the higher current and voltage required to charge multiple battery systems. They are available from RV and auto parts suppliers.

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