I’ve found that adding additional batteries actually puts MORE strain on an alternator because it’s left trying to maintain current flow and charging capabilities to TWO batteries instead of the one it’s designed to accomodate. This would make the alternator work twice as hard in theory.

The whole reasoning behind adding a second battery is for competitors to be able to run their systems for extended periods of time without the engine running. However, once the engine IS running the alternator has twice as much work to do keeping both batteries fully charged and functional.

As with ANYTHING in the world of car audio, getting things right (in your charging system or any other component of your system) and doing it right from the start will save you a TON of headaches…and money.

Car audio is a science…most people think they can just hook things up and…BAM, their set. Not quite that simple though.

Before ANYTHING else is done to your charging system do the following “Big 3″ upgrade:

Upgrade the following 3 wires with larger (4AWG minimum…preferable #2 or 1/0)

1.Cable from battery (usually through fuse box & if not add an inline fuse rated for the alternator’s capacitance) to (+) post on alternator

2.Cable from battery (-) post to chassis of vehicle ( usually done with a short (6″ or so) piece of wire to the side of the engine bay).

3.Cable from engine block to chassis of vehicle (any bolt connected to the engine block & any bolt connected to the chassis will work).

This “Big 3″ upgrade is probably the single most important step in upgrading your charging system. Best of all, these upgraded wires can simply be added over the top of the existing 16-18AWG wires already in place! This upgrade will increase the current flow from battery/alternator back to your amp as well as the return current flow from the amp back to the battery/alternator. 16-18AWG wire like the factory uses has such a limited amount of current it can carry when comparred to the much larger wire used on power & ground connections to your amp. This increased ability allows the increased flow from the amp power/ground wires to return back to the battery/alternator with much better efficiency thus completing the circle of electricity in a better fashion. This upgrade is known to either severely reduce or even eliminate headlight dimming/voltage drops to your equipment/etc. and can save your ass big time because voltage drops can fry an amplifier!

I hope this helps you out…if you have further questions feel free to email me and I’ll help in any way I can (lakerfan93449@yahoo.com)

Good Luck!

If your total system power is more than 1000 watts RMS you will need to:

1. Upgrade the alternator to a high output alternator
2. Upgrade to a heavy duty deep cycle battery
3. Upgrade the “Big 3″ - that is to replace the power wire between the battery and alternator, the ground wire from the battery to the chassis and ground strap from the chassis to the engine block or transmission to at least a 2 AWG wire.

Failure to do this will result in you replacing them anyway as the alternator will eventually fail.

Here is a guide that will calculate what size alternator and power wires you need

You’ll need Microsft Excel to use it.

See my site for more info