Car Amplifer????

Question

If i want to run a amp off a seperate battery in my trunk, how long would the battery last... would the watt of the amp make a difference of the life of the battery... and if so, what is a good brand battery to get???

Answer 1

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.

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.

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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While the article that Javin M provided held true at one time, there are a few things 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.

Answer 2

If you connect the battery to your power system, like you should, it will last indefinately so long as your alternator works. On the other hand if you want to have it as a stand alone power supply you can do the math. Say your amp is 1000W, that would mean RMS usage of about 400 W. A normal car battery is in the range of 65 Amp-hours. So 400W/12V = 35 Amps. That means you can run your amp for 2 hours off the battery alone. Also what you are really looking for is a capacitor not a battery. A capacitor is hooked into your electrical system and stores energy for high demand situations like bass thump. Chose a cap that is comprable to your system ie. 1000W amp = 1.5 Farad cap. They cost about $50 for a 2 Farad; online. The brand does not matter, they are simply plates of metal separated by a dielectric. It could be made of glass and aluminum foil and would work just as well as a gold and tantalum one, the only difference would be the size of the unit.

People who say caps dont work should be on Pimp My Ride. If you know your a$$ from your elbow you would realize that yeah, you can not run a system from a cap. And yes a cap is designed to provide an instant current along a continuously dropping voltage curve. (google: RC circuit) That being said, it is the perfect solution to a powerful amp running fine at nominal volume but dimming the lights when the bass hits. The voltage drop of a cap is miniscule compared to the voltage drop across 12ft. of 6GA wire running from your "yellow top" (google: complete BS usless crap for people who belive anything in an advertisement) to the amp in your boot.

Wiring your battery with an isolator?

Yes you're right, if you are going to use the battery as the sole power supply for your "ghetto blaster" then its a pretty good idea to isolate it. This way if you and your boyfriend decide to spend two hours riding the subs instead of the 10 minutes your really need, your car will still start. If, on the other hand, you are using it as a capacitor then by all means hook it do your alternator with the original battery in parallel. This will not, in any way shape or form effect your alternator. The battery charges at whatever rate the alt. puts current out at. Batteries in parallel increase capcitance so 2 65 A-h batteries in parallel would have a total capcity to provide 130 A-h of juice at their nominal voltage. There is no sudden "load increase" from a battery in parallel. Otherwise, those morons replacing their perfectly good stock battery (65a-h) with a yellow top (85A-h) would screw up their alternator.

The yellow top

I have been racing solar cars for about a decade and am a chemical engineer. I have seen every type of battery technology from the standard lead acid to the lithium polymer to the nickel metal hydride. The discharge mode of a lead acid battery and "deep cycle" lead acid battery is exactly the same [thats why the provide the same voltage] (google: electrochemical cell or galvanic cell, half cell potentials are set for a checmical combination). Your yellow top is just a slightly more concentrated regular battery that has thicker lead electrodes and the cells isolated from on another vertically instead of horizontally. In the long run this has no effect on discharge/recharge cycles and is a fools solution to a problem of buying a system that fits your alternator.

Alternator.

I will admit that buying a bigger alternator is the right solution to a problem of a system draining the battery.

Answer 3

Yes you can install any amp an subwoffer in any car but if you still have your factory radio in your car it is a bit more difficult to do. It can still be done but you will need an f.m transmitter an you will hear a whimming noise through your speakers an it will get annoying real fast. I suggest you buy an aftermarket radio before having amp an subs put in but it up to you. As far as pricing for installation it depends where you go. Most shops charge by the job not hourly an I'd say you looking at 200 250. I do this for a living an I have seen prices range very differantly from place to place. I personalty for an amp an a sub install would charge 125 if you had all the wires needed to do the job but that's me. I will not install an f.m transmitter though Cuz there garbage an a waste of money.

Answer 4

If you're planning to get a second battery for use while the engine's running, see above; it's not a good idea.

If you want to add a second battery for extended play time while the engine is off, then you need a deep cycle battery. A deep cycle battery is different from a normal starting battery because it can be drained and recharged repeatedly without damage. An example of a deep cycle battery is an Optima yellow-top.

There's not much point to doing this unless you get a battery isolator, which keeps the first battery from being drained while you're playing the system from the second battery with the engine off.

Answer 5

i wouldnt listen to the 1st answer. caps are crap. your much better off going with something like this
http://www.sonicelectronix.com/cat_m162_i228_kinetik-deep-cycle-batteries.html

kinetik is a good brand you can check out their website at kinetikpower.com
the hc600 is like having 100caps in your car and its an actual battery. caps are only good for a split second. the size of the kinetik you want would depend on the power of your system.
you can also get something like this
http://www.sonicelectronix.com/item_5287_PAC+200.html
thats how you connect to batteries.

Answer 6

I hate to say it, but 'ol Sparky is right. I've burnt up a few stock alternators with 700-1100 watt systems, despite having a cap and 2 gauge wires.

Answer 7

If you add a second battery without using an isolator, damage to your alt. may result.
Crapacitors DO NOT work. I now have documentation to back it up.

Read, Apply, and Learn:
http://forum.realmofexcursion.com/showthread.php?t=17970

Good Luck!