Upgrading the charging system

How do I determine when to upgrade my alternator, battery or add capacitors to my audio system? Determining what component of the charging systems needs upgrading is directly related to what the current requirements of the audio system are. Most OEM charging systems are designed to supply factory loads with up to 30% extra capacity factored in for safety reasons. Upgrades to the charging system for audio system requirements can be the addition of:

• High output alternators
• Additional batteries
• Connecting Punch capacitors
 

Alternators

If the average current draw of the audio system exceeds the maximum output of the alternator by a large amount, then it might be time to consider an alternator upgrade. A simple test is to start the vehicle, turn on the most commonly used vehicle accessories, then crank the audio system to full volume just under clipping. If the average battery voltage is above 13 volts, then the battery will receive sufficient charge from the alternator. No need to replace the alternator here. Assuming that the average current draw of the system is too high for the OEM charging system and the average battery voltage drops below 13 volts, it would make sense to install a high output alternator rather than extra batteries. Remember that when the vehicle is running, the battery is a load to the alternator.

Keep in mind that the high output alternator should have more output than the OEM alternator and high engine speeds, but may have less output than the OEM alternator at idle speed. If the vehicle will be driven in heavy stop and go traffic, the battery may not receive a sufficient charge.

 

Average current draw of the audio system and vehicle accessories exceeding the current capacity of the alternator and battery.

Additional Batteries

The addition of a secondary battery will increase the amount of time you can listen to the audio system with the engine not running. When the engine is running, the secondary battery is an additional load to the alternator.

When adding additional batteries, the simplest and most effective method is to parallel the batteries together using a 200 amp solenoid switch to connect them when the engine is running.

 

Additional Battery Considerations
Review these considerations before adding additional batteries to your charging system.

• All batteries in a charging system should be of like type, size, age, and brand. This will ensure that all batteries charge and discharge characteristics are the same.
• The additional batteries should be placed in a warm location near to the alternator. The batteries chemical reaction slows down in cold conditions.
• Upgrade the OEM battery ground to chassis and alternator ground to chassis with a minimum 4 gauge cable.
• Keep all power and ground leads to the additional batteries as short as possible.
• To minimize noise problems and maximize charging efficiency, keep batteries up front in the engine compartment.

Adding Capacitors

The Connecting Punch capacitor has the ability to charge and discharge very quickly and can store a substantial amount of current. Car audio amplifiers that play music consume current in very fast, short gulps. The capacitor lends itself very well to this type of charge and discharge rate because it’s low internal resistance.

Considerations when installing a capacitor:

• A good rule, 1 Farad of capacitance per 1000 watts of amplifier power.
• Mount capacitor as close to the amplifiers as possible.
• Charge capacitors with a 1 watt 50 ohm resistor until they reach the systems static voltage, then connect them using the same size power and ground wire as the amplifiers.

Types of Audio Systems

Before you can determine what upgrades are needed for your charging system, you must know what the intended purpose of the audio system is.

Audio systems are split into two categories:

1. System that play test tones for SPL competitions
2. Systems that play music

Both may have similar components, but require completely different amounts of current to operate properly.

SPL Systems

Reproducing the test tones that usually accompany SPL systems requires the amplifier to produce continuous high power levels that do no vary. Unlike music which is constantly changing, test tones are fixed in level which means continuous current consumption by the amplifier. In some instances, amplifiers that are used for SPL are set up to clip quite heavily which also increases current draw.

The following chart shows the current draw by a typical high power car amplifier. The amplifier is fed an all bits high test tone at clipping. Notice that the current draw remains constant for the duration of the test at about 43 amperes. This would represent the amount of current the amplifier would draw in a typical SPL system.

 

Take in consideration that most SPL systems usually have multiple high power amplifiers that have very high current consumptions of up to several thousand amperes. In this instance, the SPL system would require either multiple alternators or banks of Connecting Punch batteries to maintain the current capacity of the system. Capacitors do little for SPL type systems because the duration of the test tones exceeds the capacitors discharge time. Since the current draw is constant, the capacitor has no chance to charge to potential.

SPL System Charging System Upgrade

The optimum solution for upgrading an SPL charging system is done by adding the following:

• Multiple high current alternators
• Banks of Connecting Punch batteries

Systems That Play Music

Without changing the volume from the previous SPL test, play music with high levels of bass into the amplifier. Even though the bass CD has compressed dynamics, it still varies in level dramatically compared to the test tones in the previous SPL test.

The current draw in this situation has peaks that reach about 33 amperes and an average level of about 20 amperes. When producing the bass music, the amplifier drew around 50% less current that the SPL system did using test tone sine waves. It should be obvious that there is a very large difference between reproducing music and test tones with an audio system.

 

If the audio system that plays music is taxing the OEM charging system, upgrading is quite simple. If you refer to the current draw diagram when playing music, you will notice that the actual current draw fluctuates between 15& 30 amperes most of the time. Since the average current draw is not very large and is not constant , a Connecting Punch capacitor would be the recommended addition to the charging system.

Systems that Play Music Charging System Upgrade

The optimum solution for upgrading a charging system for systems that play music is done by adding the following:

1. Connecting Punch capacitors

Summary

• For a system designed to reproduce music, capacitors are the simplest, most reliable upgrade you can make
• Extra batteries are great for extending listening time of the audio system when the automobile engine in not running, or for SPL type systems
• Upgrading to high out put alternators will improve the current output at high engine speeds but usually do not help when the automobile engine is at idle. Alternator swaps can be tricky and may require a professional to perform the installation.