how to run a 2nd bat.

[audiolife 5,000+ posts]

ohhh i give taxi a 98%

 

[PESteele 10+ year member]

i dont think theyve been replaced before so probably 10 years. Ill ask my dad though. They put out alot of juice though cause i need to use both my parents cars to jump it

 

[PESteele 10+ year member]

what do you think would be better to replace them with cause id like to be able to play a lil w/ the car off.

 

[Thnking 10+ year member]

It isn't nearly that simple. I could put the biggest alt made in my car and I would still get dimming. My factory alt is 165A but I still get dimming. The alt itself could theorectically react instantly but the voltage regulator has a voltage threshold that must be reached before it causes the alt to react. In some cases, the voltage regulator won't do anything unless the voltage dip is of a certain duration (measured in seconds in the case of my car) as it is part of the ECU and will up the engine idle RPM before upping the output of the alt.

Don’t get me wrong, my explanation isn’t simple.

Reaction rate is going to be the equivalent from alternator to alternator, it’s limited by mechanical means and is much faster (a few ms to 10ms) than we can perceive. Voltage regulators adjust the field cycle typically 2-3x as fast as this, this is how they are set. That’s pretty standard, for electromagnetic regulators. PWM regulators typical duty cycles are around 5-10x that.

In your car it sounds like the voltage regulator is part of the engine computer controller, pretty common. In your case it’s not the alternator’s or voltage regulator’s lack of reaction time, it’s the fact that at idle the load can’t be supported by the field adjustment or resistance adjustment of the voltage regulator. So after a set point amount of time the computer increases idle. A very different issue.

A battery has a skin voltage that is higher than its nominal voltage, basically the same as the charging voltage. It will begin to contibute current as soon as the voltage begins to drop. Consider also that having a battery near the amps will also eliminate the voltage drop caused by the cable run from the front of the car to the rear and the gain from adding one should become more apparent.

As the term implies, “surface charge” has very little relationship with chemical vs electrode reaction in a battery. So while a battery may exhibit a higher than normal voltage due to the surface charge, current discharge is very low for the surface charge potential.

And yes a battery will eliminate the extra wire Vdrop by having it in the rear, which is only going to significantly discharge below 12V, probably closer to 11V. And the Vdrop should be very low to begin with, because the wire should be sized properly.

The determining factor on whether or not you need a HO alt is the average current drain of the system. With most daily systems and music the average draw is actually really low (

If the wiring and the alternator are properly sized, there should be no perceptual dimming. Average load means nothing without implying a specific time integration. The alternator should be selected based on average estimated transient load, not total load. Once this is met, which can easily be done with most non-competitive systems, there won’t be any problems. Unlike the results from adding batteries, which won’t eliminate large voltage drops.

 

[audiolife 5,000+ posts]

lol this guy cracks me up

 

[yacob.naif 10+ year member]

i dont think theyve been replaced before so probably 10 years. Ill ask my dad though. They put out alot of juice though cause i need to use both my parents cars to jump it

i feel your pain, when my battery died in the e250, i had to have a towtruck come, cause nobody could jump me

this was just last night, actually

it was like 17 degrees outside, and the gas station i was at closed like a half an hour before the tow truck got there

 

[audiolife 5,000+ posts]

what makes the alt/regulator slow is the ever changing load placed upon it also if the battery was "so weak" in the set up the regulator would be toasted in very little time like 6 months to a year (diodes in a regulator can die in under a few minutes when you remove the battery from the alt with the vehicle running)

 

[helotaxi 5,000+ posts]

As the term implies, “surface charge” has very little relationship with chemical vs electrode reaction in a battery. So while a battery may exhibit a higher than normal voltage due to the surface charge, current discharge is very low for the surface charge potential.

Car batteries have a capacitance value will allow for a significant discharge from the skin voltage.

And yes a battery will eliminate the extra wire Vdrop by having it in the rear, which is only going to significantly discharge below 12V, probably closer to 11V. And the Vdrop should be very low to begin with, because the wire should be sized properly.

Under a large current load, a V drop of 1V front to rear in the car is pretty common even with 1/0 wiring. Add to that the fact that if your battery is only providing 11V under a load coming off a full charge, then it's shot.

If the wiring and the alternator are properly sized, there should be no perceptual dimming. Average load means nothing without implying a specific time integration. The alternator should be selected based on average estimated transient load, not total load. Once this is met, which can easily be done with most non-competitive systems, there won’t be any problems. Unlike the results from adding batteries, which won’t eliminate large voltage drops.

Your whole argument is based on a series of faulty assumptions, the most glaring of which is that resistance losses in the system are negligible. Not only are they significant but they obviously increase with the current load. With the car running and the system off, you will measure the alt voltage at the amp terminals all day, but turn on the system even at low volume and the voltage will drop measurably because of the increase in current. The basic premise that you are arguing against has been proven more than once by multiple different people. If you were right, then it would be a waste for the high level competitors to have banks of batteries, because they have 4 huge alts and their cars are running during metering. According to your logic, their voltage should be stable without those batteries.

Basically what it all comes down to is your premise that a second battery does nothing to help with voltage dips during dynamic music is not valid with most cars or most daily systems. Adding a battery can help and help a lot for most people.

 

[Thnking 10+ year member]

Car batteries have a capacitance value will allow for a significant discharge from the skin voltage.

LOL, oh really…and what exactly is the capacitance value in proportion to surface charge.

Under a large current load, a V drop of 1V front to rear in the car is pretty common even with 1/0 wiring. Add to that the fact that if your battery is only providing 11V under a load coming off a full charge, then it's shot.

Give me a break, 1V…LOL.

Even with 20’, the resistance is going to be under .002ohm.

1V=I*.002

That’s 500A, which also is well above any recommended ampacity for the 1/0 wire.

There’s nothing wrong with relocating the battery, but it’s not going to have any significant effect on Vdrops along the line.

Your whole argument is based on a series of faulty assumptions, the most glaring of which is that resistance losses in the system are negligible. Not only are they significant but they obviously increase with the current load. With the car running and the system off, you will measure the alt voltage at the amp terminals all day, but turn on the system even at low volume and the voltage will drop measurably because of the increase in current. The basic premise that you are arguing against has been proven more than once by multiple different people. If you were right, then it would be a waste for the high level competitors to have banks of batteries, because they have 4 huge alts and their cars are running during metering. According to your logic, their voltage should be stable without those batteries.

I never said resistance is negligible, I said resistance in wiring should be properly matched to load to minimize opposition to current. Once that is done resistance isn’t significant.

Competitors use batteries based on completely different reasoning. Banks of batteries are easier to install and provide very large amounts of current for short durations. 1 battery may be able to discharge 400A for a sec over 2V potential. But that in 2 banks of 4 batteries, and we have very large capacity.

Trying the same thing with an alternator is much different. Alternators increase current output, to begin with, with an increase of mechanical energy. They also are regulated to produce variable fields. Those make them difficult to properly adjust for purely a competitive standpoint. They also, aren’t made regularly to provide as much current as a large battery. And 4 alternators don’t fit under any hood I’ve ever seen.

Basically what it all comes down to is your premise that a second battery does nothing to help with voltage dips during dynamic music is not valid with most cars or most daily systems. Adding a battery can help and help a lot for most people.

Only if the dimming is very bad, or voltage drops are very large…in which case the alternator isn’t large enough to begin with. Wiring and source (alternator) should be matched to the load, period.

 

[audiolife 5,000+ posts]

thnking you really need to earn how to apply everything and how everything is relative to eachother. you can throw out 90000 equations i dont care they dont mean **** if not applied right

 

[Thnking 10+ year member]

what makes the alt/regulator slow is the ever changing load placed upon it also if the battery was "so weak" in the set up the regulator would be toasted in very little time like 6 months to a year (diodes in a regulator can die in under a few minutes when you remove the battery from the alt with the vehicle running)

What makes the alternator "slow" is the cycling of the field. If the load is proportional to the alternator's max output, the field must be cycled to full. Make the alternator larger, and there aren't any dimming problems and the alkternator is "fast" again.

 

[Thnking 10+ year member]

thnking you really need to earn how to apply everything and how everything is relative to eachother. you can throw out 90000 equations i dont care they dont mean **** if not applied right

I look at things from a realisitc standpoint, and have first hand experience technically with what I'm discussing.

Any equation I apply to anything denotes the physically way it operates.

It seems like this is all ruining your imaginary perception of how batteries work.

 

[audiolife 5,000+ posts]

What makes the alternator "slow" is the cycling of the field. If the load is proportional to the alternator's max output, the field must be cycled to full. Make the alternator larger, and there aren't any dimming problems and the alkternator is "fast" again.

you are on crack . the amount of power an alt can do is dependant on two things the load and rpm.... the reactance to either of these is a factor and takes time in anyway you want to look at it lol

 

[audiolife 5,000+ posts]

I look at things from a realisitc standpoint, and have first hand experience technically with what I'm discussing. Any equation I apply to anything denotes the physically way it operates.

It seems like this is all ruining your imaginary perception of how batteries work.

nope not in the least.....

 

[Thnking 10+ year member]

you are on crack . the amount of power an alt can do is dependant on two things the load and rpm.... the reactance to either of these is a factor and takes time in anyway you want to look at it lol

The cause of the dimming is the excitation of the stator to a full field.

A transient load doesn't necessarily cause the voltage regulator to cycle to field to a full excitation. It relative to alternator output potential at a given stator speed vs load x duration. The actual reaction of the alternator to the faster regulator is around 5-10ms.

I hope that's easy enough for you to understand