Do I Need To Have Anything Special In Order To Install 2 Car Batteries On My Stereo System.
Posted in Car Batteries | Asked on Apr 10, 2010
Hello,
I have noticed recently, even with the addition of a 3 farad capacitor that my headlights tend to dim at musical peaks. I have an optima Yellow top battery, a factory alternator that has sufficient power to charge it, and a capacitor. I’m not sure if getting a high performance alternator, or an additional battery would be the best. However, I do plan on getting both some time. My question is if I do get a 2nd battery, do I need to do anything special to wire it into my system? Also, would those BatCap’s that I’ve seen around recently be worth the while to get instead of a second battery.
Thanks
There are 3 Answers
Go to a camping store or website and get a battery isolator. This allows you to hookup your accessories (music stuff, or whatever) to your second battery. The isolator is hooked up to the alternator between the alternator and the second battery. The isolator allows the 2nd battery to charge off the alternator but the draw from the accessories does not reverse, meaning it doesn’t affect the alternator or the main battery. You could be parked, running your accessories and only the 2nd battery would drain, not even touching your main battery for startup. This would fix the drain at musical peaks but also allow you not to worry about draining your batteries when parked.
Running a second battery is never a good idea as it’s just an added strain on the alternator. A cap is only good so far as the audio system isn’t trying to pull too much from the electrical system. Auto manufacturers take into account that 40% of the alternator power is required to run the electrical system (AC, fans, lights, etc.). If your audio system consumes more than 60% of the alternators power, an alternator upgrade is recommended as is the Big 3.
I know a cap can be beneficial as I’m running one and I measured a definite change in my electrical systems response curve to big bass hits with an oscilloscope, however, this won’t be the case for ALL vehicles as power demands differ.
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 and the ground strap.
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 http://www.datafilehost.com/download.php?file=6d26c621
You’ll need Microsft Excel to use it.
See my site for more info http://spkrbox1.spaces.live.com
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Javin M will come along and give an explanation on how caps are worthless. He’ll even provide a site that explains this http://forum.realmofexcursion.com/showthread.php?t=17970
While the article that Javin M (and I) provide held true at one time, there are a few errors that time has altered. This article was written some time ago and changes have occurred in the manufacturing of capacitors. In the article an ESR of .017 was given, the problem is that caps made today have an ESR of 0.0016 or less which is a far cry from the days of old.
What does this mean? It means the calculations and information now change quite substantially and can no longer be held as true.
Yes, a second battery will help. Do NOT use a battery isolator. They are just gigantic diodes with heat sinks. They have a voltage drop and waste power in the form of heat. If you pay attention to your batteries’ voltages, you don’t need to buy anything. If you want to be able to just forget about your batteries, than buy yourself a high current solenoid. Solenoids offer everything good about an isolator, but none of the drawbacks. They are effectively just high current relays which disconnect the main battery when your vehicle is turned off. While a second battery is an additional load on your alternator, so are caps. Any device that requires charging is a load. Get another battery. You’ll be fine. You should upgrade your alternator, but you don’t necessarily have to. Batcaps are powerful and lightweight, but they have nowhere near the capacity of a battery. Just make sure you have a circuit breaker between the second battery and the feed from your main battery (as close to the second battery as possible). Otherwise, if the power cable grounds out anywhere, your old fuse would blow, but the second battery would still ground out.