Extra Batteries?

[Ryan shaw 10+ year member]

I have done some research on charging systems and i keep seeing that your alternator is the only thing supplying power to your amps with the car on. So if this is true by my understanding, the only thing second batteries do is prolong your car off listening time? or is it something like extra batteries give you more instantly available power to reduce voltage drop on heavy current draw notes?

I guess i just dont see why everyone with high power systems seem to always have at least 1 battery in the back if all it does is prolong your car off listening time. please correct me if i'm wrong, which i probably am lol, thanks!

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[All_Logix 10+ year member]

I'm no expert on extra batteries but I am in my last year of Electrical Engineering, what you have to consider is that the way the battery under your hood and the alt is configured, the alt sends a current in the opposite direction through your battery to recharge it and the battery acts a filtering cap making sure the AC current from the alt does not pass through into the DC circuit for your car. By placing an extra battery in line with the amps you are adding more voltage to the mix (voltage in series sums the net voltage), and since the current is a constant from the alt will produce more power (watts=volts*current)...in short it makes it easier for your amp to reach a certain voltage at the output without consuming as much current. Like i said I am no expert but if I have to guess this would be my thoughts on it

 

[winkychevelle 10+ year member]

No most of the installs u sell have amps that draw 300+ amps of current try finding an alt big enough to push that amp and the car. It's cheaper to have a battery bank that can discharge the current needed and recharge during time when very little current is being pulled. Alternators don't put out ac voltage they are dc and the battery only act as a filter because Alts tend to vary voltage from 13-15 volts sometimes even more. And electronics are generally sensitive to voltage change. As far as more batts mean more power, well that's wrong because you aren't changing voltage if you add and extra battery u are only holding the same voltage longer. Unless u connect the batts In Series which is a really bad thing to do in car audio as amps don't like that high of voltage 18v max on high voltage amps 15v on normal amps

 

[DBBOOM 10+ year member]

I have done some research on charging systems and i keep seeing that your alternator is the only thing supplying power to your amps with the car on. So if this is true by my understanding, the only thing second batteries do is prolong your car off listening time? or is it something like extra batteries give you more instantly available power to reduce voltage drop on heavy current draw notes?
I guess i just dont see why everyone with high power systems seem to always have at least 1 battery in the back if all it does is prolong your car off listening time. please correct me if i'm wrong, which i probably am lol, thanks!

So you answered your own question in the first post. What do you want us to say?

 

[All_Logix 10+ year member]

No most of the installs u sell have amps that draw 300+ amps of current try finding an alt big enough to push that amp and the car. It's cheaper to have a battery bank that can discharge the current needed and recharge during time when very little current is being pulled. Alternators don't put out ac voltage they are dc and the battery only act as a filter because Alts tend to vary voltage from 13-15 volts sometimes even more. And electronics are generally sensitive to voltage change. As far as more batts mean more power, well that's wrong because you aren't changing voltage if you add and extra battery u are only holding the same voltage longer. Unless u connect the batts In Series which is a really bad thing to do in car audio as amps don't like that high of voltage 18v max on high voltage amps 15v on normal amps

Your right, I didn't think about the sensitivity to voltage change on the electronics, but I can promise you your alt produces AC...it just gets rectified into DC through a series of diodes

 

[winkychevelle 10+ year member]

Your right, I didn't think about the sensitivity to voltage change on the electronics, but I can promise you your alt produces AC...it just gets rectified into DC through a series of diodes

All this must happen inside the alt because your alt leads send dc power to your battery. Look at a houses wireing for ac voltage. You have a common a hot and a ground. Cars only have a hot and a ground so the power can only move one way no switching wires for alternating current

 

[All_Logix 10+ year member]

All this must happen inside the alt because your alt leads send dc power to your battery. Look at a houses wireing for ac voltage. You have a common a hot and a ground. Cars only have a hot and a ground so the power can only move one way no switching wires for alternating current

Oh yeah man, I'm not debating that it sends a DC voltage through to the car, but common alternators use a three phase AC circuit that have a two diode bride to each phase. AC current is the only thing that can be produced electrically that I know of from mechanical energy because it runs off of electromechanics. all of it is contained within the alternator, but sometimes an AC ripple will get out and that is where the battery can act as a rectifier.