What Size Auxiliary Battery Can the Original Vehicle Alternator Charge?
2 Answers
The original vehicle alternator can charge an 80A auxiliary battery. Related information: 1. Introduction: The car alternator is the main power source of a vehicle, whose function is to supply power to all electrical devices (except the starter) while the engine is running normally (above idle speed), and simultaneously charge the battery. 2. Expansion: Based on the three-phase stator winding of a conventional alternator, the number of winding turns is increased with lead-out terminals, adding a set of three-phase bridge rectifier. At low speeds, the output is provided by the series connection of the original and additional windings, while at higher speeds, only the original three-phase winding provides the output.
I often modify car circuits, and adding an auxiliary battery requires considering the alternator's remaining capacity. The original car alternator typically outputs 60-180 amps, but it consumes power itself—for example, headlights use 10-20 amps, leaving 40-100 amps for charging. The main battery is usually 50Ah, and the auxiliary battery is recommended to be 50-100Ah; too large a battery can easily overheat the alternator. Using lithium or AGM batteries is more efficient, but an isolator must be installed for protection to prevent the main battery from draining. Charging for a few hours while driving is sufficient—avoid idling to charge, as it's inefficient and harms the engine. Long-term overload can burn out the alternator's coils, leading to costly and troublesome repairs.
