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GlassWolf wrote:the secoond battery isn't going to help when the car is runing.you'd need a larger alternator.see the FAQ section on charging systems.

Why wouldn't the Extra batt help while the car is running? Are you saying it wouldn't help keep voltage up. The two batts would act just as one BIG battery anyways..running a second batt has helped in my experience, but you tell me the facts :) .

When your car is running it should be getting all it's power from the alt. not the battery. The battery is mainly used to just start the car, and for engine off power.
Running another battery is also going to put additional strain on the alt because now it has to try and keep 2 batteries charged, instead of one, plus run all the electronics in the car when it's running.

there's a thread in the guides area on speaker power handling. worth reading.

as for the batteries, the battery should be in a charging state when the car is running. If the car's voltage alternator is being overdrawn to the point that you have to rely on the battery for more than the occasional momentary drop to 12 volts, you have problems, and a second battery may extend runtime a bit but you're still clipping the amplifiers, and still damaging the alternator.

fact is the alternator should supply all the needed current for the car when the engine is running. that's why the alternator voltage is higher than the battery voltage. to charge the batteries.
a car battery has one purpose. to supply power enough to turn over the engine and start it.
after that the battery should at most, act as a DC voltage filter.

GlassWolf wrote:there's a thread in the guides area on speaker power handling. worth reading.
as for the batteries, the battery should be in a charging state when the car is running. If the car's voltage alternator is being overdrawn to the point that you have to rely on the battery for more than the occasional momentary drop to 12 volts, you have problems, and a second battery may extend runtime a bit but you're still clipping the amplifiers, and still damaging the alternator.
fact is the alternator should supply all the needed current for the car when the engine is running. that's why the alternator voltage is higher than the battery voltage. to charge the batteries.
a car battery has one purpose. to supply power enough to turn over the engine and start it.
after that the battery should at most, act as a DC voltage filter.

I was just trying to make it a point that they can be useful while the car is running (whether or not it's the best way of doing things) as far as voltage dips go.

a shot of penecillin can be useful if ya get the clap too, but isn't it better to avoid getting the clap instead?
:)

GlassWolf wrote:a shot of penecillin can be useful if ya get the clap too, but isn't it better to avoid getting the clap instead?
:)

Yup.

Really, it's gunnna depend on how loud he plays his system anyways. If I run my Viper D1200.1 ran down to 1ohm (rated for 1200x1@1ohm) on volume 30..I have absolutely NO problems with voltage drop even at idle..now when I turn it up to volume 45..I obviously start getting a slight drop. Thats with a stock 90A alt. So, if you tend to play your volume at moderate levels..the alt may never be an issue, but many love to crank the volume knob :happy055:

With a second battery, it will definately keep your voltage from dropping low when current is in demand. BUT, given the additional 10 amp load, you alternator will be hurting more than before.

Not quite the same effect as adding a cap, but it is similar.