Been doing a TON of research on charging system, now need experts!

[thatkidbob 10+ year member]

CCA and reserve capacity (in my opinion)

internal resistance is kinda important, but i dont think it matters much with the amount of power you're running...

 

[knukonceptz 10+ year member]

aH - ampere hour, higher the better

 

[Thnking 10+ year member]

I would hook it up stock, if you start having voltage drops then buy a more powerful alternator.

2 batteries won't help you with your drop's from a alternator which isn't powerful enough.

 

[knukonceptz 10+ year member]

A second battery will stabilize the voltage. It will provide bursts of amperage that the system requires. The big SPL guys use batteries for a reason and other classes are limited to one or no batteries because they work. Keeping voltage stable is what helps the amps run more efficient. An efficient amp will last longer and create less heat (meaning more power)

 

[Thnking 10+ year member]

Sure it helps during the discharge when the voltage drops below the batteries potential (12. whatever), but there's going to be a 2V+ drop before the batteries even can impact the car's voltage in any significant manner.

Big SPL guys use banks because they can get a ton of output below 12V (or higher if they use a battery with higher/more cells), there's no retail alt which can produce the same current.

In reality keeping the voltage as high as possible (not stable) keeps the amplifier efficiency up. Which is one reason people should look to upgrade the alternator before the battery, if it’s possible.

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[knukonceptz 10+ year member]

You have a system in your car - turn it on start your car and play some music. See what the voltage does at the front battery (not of a block or cap - a real DVM on the battery). with MUSIC it will bouce around, but never drop conitously. Have a friend pull up next to you, connect his battery to your car with jumper cables. Let your car run for 30 seconds with his connected to make sure both batteries are equal - see what happens to the voltage now. Its easy and free learning

 

[Thnking 10+ year member]

Your example is not related to your discussion. If someone has their car running (their alternator running) and they make a connection with your electrical system they are providing current with their alternator's potential (14.whatever volts). For that to mean anything the person would have to turn their car off, and their connection would have to be parallel to your circuit.

But I know it’s not going to stop whatever you think is happening because I've wired batteries in parallel before, and I understand the concepts of it very well.

The typical reaction time of an alternator is around .7ms +-.2ms (voltage regulator is around 5x that). This covers any load due to bass. Disregarding bass then, unless someone is packing a huge midrange to high freq. system, the voltage is going to remain pretty stable.

We're talking beyond any tolerable listening levels from midrange and tweeters with any properly sized modern alternator.

Like I said if the alternator is properly sized, your voltage isn't going to be jumping more than a couple tenths of a volt (unnoticeable) with heavy loads. A battery isn't going to provide any current until the circuit potential is low enough.

That's free advice as well, and saves you from buying your friend a beer for wasting their time.

 

[knukonceptz 10+ year member]

Obviously the second car would be off and in parallel, sorry for not being clear. Certain regulators are not instant, so it really depends on the application.

Regarding voltage level and amp efficiency - if a stable power supply is not top priority, why are caps used in an amp's power supply - they stabilize the power, they certainly dont keep voltage high, they just help smooth spikes.

In any large application, the current draw during a Sweep or test tone can easily out draw even a HO alternator. Not many cars can get a 250-300A Alternator under the hood. While a bigger unit will help, having the reserve power on hand is very hard to beat. Half of the daily systems can get by with a simple second battery upgrade rather then a high dollar HO Alternator.

 

[audiolife 5,000+ posts]

Obviously the second car would be off and in parallel, sorry for not being clear. Certain regulators are not instant, so it really depends on the application.
Regarding voltage level and amp efficiency - if a stable power supply is not top priority, why are caps used in an amp's power supply - they stabilize the power, they certainly dont keep voltage high, they just help smooth spikes.

In any large application, the current draw during a Sweep or test tone can easily out draw even a HO alternator. Not many cars can get a 250-300A Alternator under the hood. While a bigger unit will help, having the reserve power on hand is very hard to beat. Half of the daily systems can get by with a simple second battery upgrade rather then a high dollar HO Alternator.

agreed back in the day we had big wet cell marine batteries and 800 dollar 160 amp alts lol. so what 90% of us did was basically add another battery that you kept an eye on and probably maintain charged 2-3 times a yr.

 

[n2audio 5,000+ posts]

what you're saying makes perfectly good sense Knu, but you make it sound like any ol' alt has infinite current and can maintain a charge on the extra battery.

You're probably aware of this -- I just think it needs to be thrown out there...

The simple fact that there's another battery means another load on the alt. Even if you run the best battery money can buy - if the alt can't produce more current (rms) than the car's electronics demand (rms), it's only a matter of time until those batteries are dead.

Competitors use battery banks because they need boatloads of current only for a few minutes at a time, which a few batteries can do with no problem at all. Then it's back on the chargers for a few hrs. Doesn't work that way in a driver.

Hell - one decent battery can crank out 300 or 400 A to crank the engine for 30 sec or so.

 

[audiolife 5,000+ posts]

also i wouldnt just use any battery unless you knew you werent draining alot of juice. agm batteries typically give you lowwer esr, more aH and no leaking acid

 

[audiolife 5,000+ posts]

what you're saying makes perfectly good sense Knu, but you make it sound like any ol' alt has infinite current and can maintain a charge on the extra battery.
You're probably aware of this -- I just think it needs to be thrown out there...

The simple fact that there's another battery means another load on the alt. Even if you run the best battery money can buy - if the alt can't produce more current (rms) than the car's electronics demand (rms), it's only a matter of time until those batteries are dead.

Competitors use battery banks because they need boatloads of current only for a few minutes at a time, which a few batteries can do with no problem at all. Then it's back on the chargers for a few hrs. Doesn't work that way in a driver.

Hell - one decent battery can crank out 300 or 400 A to crank the engine for 30 sec or so.

think in terms of the size of the load. only time i ever heard of needing the power for minutes in spl is in death matches (5 min) and alot of guys i know dont even charge during a whole finals event. im by no means taking away the importance of an alt either but in alot of arguements people say get a regular battery and a 200 amp alt. some alts dont do rated power until you are at highway speeds so at idle you 200 amp alt is say 80-100 amps you have a 2000-2500 watt system with a regular duralast 18 miliohm low reserve battery it would not be very good on the battery at low speeds / idle and definatley not good for parking and showing off your system with the engine off. in my days believe it or not i have or have seen stuff get pretty muffed by not having the right battery and thrashing entirely too much with the stereo vs what you have to support it.

 

[knukonceptz 10+ year member]

what you're saying makes perfectly good sense Knu, but you make it sound like any ol' alt has infinite current and can maintain a charge on the extra battery.
You're probably aware of this -- I just think it needs to be thrown out there...

The simple fact that there's another battery means another load on the alt. Even if you run the best battery money can buy - if the alt can't produce more current (rms) than the car's electronics demand (rms), it's only a matter of time until those batteries are dead.

Competitors use battery banks because they need boatloads of current only for a few minutes at a time, which a few batteries can do with no problem at all. Then it's back on the chargers for a few hrs. Doesn't work that way in a driver.

Hell - one decent battery can crank out 300 or 400 A to crank the engine for 30 sec or so.

If the daily driver guy is playing sweeps for every second the car is on, drawing 200-300A, yes a stock alternator and two batteries will eventually die, but no one does that. Dynamic music draws much less current any test tone will so the actual load seen on the charging system is much less then the systems full potential.

Any time the car is on and the batteries are low, some sort of charge is being put back into those batteries. It would take years before a problem comes along on most daily driven rides that have systems (that excede stock ALT output) and a second battery.

I have nothing against HO ALTs (why would I, we offer them) I am merely pointing out the OP suggested a 5 farad cap, for the money of a 5 farad cap, I would use that for a second battery instead.

 

[Thnking 10+ year member]

Regarding voltage level and amp efficiency - if a stable power supply is not top priority, why are caps used in an amp's power supply - they stabilize the power, they certainly dont keep voltage high, they just help smooth spikes.

They’re used to stabilize power for frequency response, this is unrelated to efficiency.

In any large application, the current draw during a Sweep or test tone can easily out draw even a HO alternator. Not many cars can get a 250-300A Alternator under the hood. While a bigger unit will help, having the reserve power on hand is very hard to beat. Half of the daily systems can get by with a simple second battery upgrade rather then a high dollar HO Alternator.

Not many systems have 300amp average loads. When someone does, like I said earlier, I do think that it’s time to start using battery banks….but this is going to be almost solely for competitors.

Like I explained earlier as well, a daily driver isn’t going to see reduction in voltage drops by adding a 2nd battery.

 

[Thnking 10+ year member]

If the daily driver guy is playing sweeps for every second the car is on, drawing 200-300A, yes a stock alternator and two batteries will eventually die, but no one does that. Dynamic music draws much less current any test tone will so the actual load seen on the charging system is much less then the systems full potential.
Any time the car is on and the batteries are low, some sort of charge is being put back into those batteries. It would take years before a problem comes along on most daily driven rides that have systems (that excede stock ALT output) and a second battery.

I have nothing against HO ALTs (why would I, we offer them) I am merely pointing out the OP suggested a 5 farad cap, for the money of a 5 farad cap, I would use that for a second battery instead.

You seem to be missing the point that a battery won’t discharge until the voltage drops below its nominal voltage. It’s not stopping voltage drops, only helping to stabilize the voltage drop from having a magnitude above 2V or whatever the number is.

Be it that a person plays sweeps or whatever, unless the person has huge amplifiers powering their mids and tweeters, the alternator will cover load based on bass as long as it’s properly sized. And I would hope anyone below competitor status, isn’t actually trying to listen to 2k-3kwatt loads of music, which is the relevant point of adding additional batteries.

And…if someone has a system anywhere near the point where the alternator can’t output enough to match the load, any retail capacitor is going to be absolutely useless.