5.1. How Does A Vehicle Charging System Work?

Automotive Charging Systemsshort Work | diagram and wiring schematic

INNOVA 3721 Battery and Charging System Monitor

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  • Using the example above, let's assume that an after-market, 400 watt @ 69% efficiency high-power audio system, 20 amp electric winch, or 276 watts of lights is installed that adds an additional 20 amps of load each. With a total electrical load of 34 amps, at RPM below 2500, the battery will never be recharged with an 90 amp system. While the engine is running in this case, the battery must make up the deficit. The solution is to upgrade the charging system to 120% or more of the new worst-case load. In this example and based on stop-and-go driving habits, a high output charging system capable of 105 amps or more would be required to keep the battery fully charged. High alternator temperatures can further reduce the maximum output of a charging system, so cooling and sizing based on the continuous load matters. kills alternators, so Bosch, for example, has water cooled models available.

    If the battery in your car is bad or near the end of its useful life, the alternator may not supply the required amount of alternating current (AC) to keep the vehicle operating properly. If any other components in the charging system are malfunctioning, the entire system will suffer from poor performance or system failure.

  • Batteries almost never fail at a good time. To prolong battery life, battery, terminals and cable ends should be kept clean and free from corrosion. The battery and starting/charging system should be periodically tested for proper performance. Many testers utilized today are able to predict when a battery is near the end of its useful life.

    The vehicle's electrical load is normally satisfied first by the charging system and then any remaining power is used to recharge the battery. For example, if the total electrical load is 14 amps and the charging system is producing 35 amps at 2500 RPM, then up to 11 amps will be available for recharging the battery, which will take approximately six minutes. If the charging system is operating at say a maximum capacity of 90 amps at 5000 RPM, then the battery usually will be recharged within two minutes. Now let us assume that the engine is idling and the charging system is only capable of producing 10 amps. Four amps from the car battery are required to make up the difference to satisfy the 14 amp electrical load and the battery is being discharged further. This is why making short trips, driving in stop-and-go traffic, or during bad weather when there is a heavier electrical load, the starting battery may never get recharged and may even become "completely" discharged.

    PV Battery Charging System

  • CHAdeMO
    Vehicles: Kia Soul EV, Mitsubishi i-MiEV, Nissan Leaf
    Typical Power: 50 kW
    Number of U.S. Connectors: 1919
    Combined Charging System
    Vehicles: BMW i3, Chevrolet Bolt EV, Chevrolet Spark EV, Volkswagen e-Golf
    Typical Power: 50 kW
    Number of U.S. Connectors: 1061
    Tesla Supercharger
    Vehicles: Tesla Model S, Model X
    Typical Power: 135 kW
    Number of U.S. Connectors: 2010

    A simple test to determine if the charging system is large enough is to check the battery's after the has been removed. If the is consistently above 95%, then the charging system is fully recharging the car battery based on your driving habits and electrical load. If is is consistently below 80%, then you will want to consider upgrading your charging system to produce more current or use a temperature compensated, with a quick disconnector to periodically "top off" your battery. There are several possibilities to increase the capacity of your charging system to include changing the pulley diameters, replacing the alternator with an higher output model, adding a second charging system (for a ), adjusting/replacing the voltage regulator, etc. An auto electric or alternator rebuilding shop can assist you. If you have a heavy electrical load while the engine is not running, install a with the non-starting load on a deep cycle battery battery or bank. If consistently undercharged or overcharged, a lead-acid battery will lose capacity and performance and prematurely fail due to sulfation or loss of water.

In the next section we'll look at the Magna-Charge system.

For many years, emergency equipment manufacturers and public safety departments across the nation have chosen Pro Charging Systems/Dual Pro battery chargers because of their performance and reliability.