Battery Use While Car is Running

[qtipextra 5,000+ posts]

As many people are confused (including myself) with this issue, I would like it set straight.

Does the battery help stabalize voltage and provide current when your car is running? I was under the impression that the battery doesn't provide current, put instead pulls some (to charge). So therfore upgrading your battery has no positive effects on your amperage available while your car is running? Is this correct, or not?

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[scooter924 10+ year member]

Well I could be wrong, but I think it acts as a reserve when driving. The alternator does most of the work when the car is driving, but if your system draws more amps than the alternator can supply, then the battery provides the extra juice.

 

[PhatTonyDeMarco 5,000+ posts]

Well I could be wrong, but I think it acts as a reserve when driving. The alternator does most of the work when the car is driving, but if your system draws more amps than the alternator can supply, then the battery provides the extra juice.

No you are correct on that.

 

[reneeb7363 10+ year member]

a lil more:

The alternator is a SOURCE of energy when the enigne is running, and, by its nature 'charges' the battery and provides the power for the other electrical components. It's output is regulated by the regulator. A battery has two basic functions... when the vehicle is off it provides power both through chemical reactions and its natural capacitance value. It also acts as a buffer to the electrical system (in conjunction with the regulator in the alternator) to cushion voltage spikes.

thats just my $0.02--

 

[qtipextra 5,000+ posts]

That makes sence. Thanks to who contributed.

 

[scooter924 10+ year member]

a lil more: The alternator is a SOURCE of energy when the enigne is running, and, by its nature 'charges' the battery and provides the power for the other electrical components. It's output is regulated by the regulator. A battery has two basic functions... when the vehicle is off it provides power both through chemical reactions and its natural capacitance value. It also acts as a buffer to the electrical system (in conjunction with the regulator in the alternator) to cushion voltage spikes.

thats just my $0.02--

huh? Is that a word or did you just make that up //content.invisioncic.com/y282845/emoticons/uhoh.gif.c07307dd22ee7e63e22fc8e9c614d1fd.gif

 

[DBfan187 5,000+ posts]

huh? Is that a word or did you just make that up //content.invisioncic.com/y282845/emoticons/uhoh.gif.c07307dd22ee7e63e22fc8e9c614d1fd.gif

http://en.wikipedia.org/wiki/Capacitance

 

[scooter924 10+ year member]

Cool, thanks. Just never seen the word used before.

 

[Thnking 10+ year member]

As many people are confused (including myself) with this issue, I would like it set straight.
Does the battery help stabalize voltage and provide current when your car is running? I was under the impression that the battery doesn't provide current, put instead pulls some (to charge). So therfore upgrading your battery has no positive effects on your amperage available while your car is running? Is this correct, or not?

I agree with the other poster as well, a battery isn't going to play a significant role unless the alternator isn't properly sized. Alternator and wiring should be the #1 concern.

 

[audiolife 5,000+ posts]

I agree with the other poster as well, a battery isn't going to play a significant role unless the alternator isn't properly sized. Alternator and wiring should be the #1 concern.

show me an alt that can put out 500 amps of current on a whim..also an alt is not flip a switch and it does full power.

 

[oxsign 5,000+ posts]

I love threads like this where one can accually learn something. Great thread guys. //content.invisioncic.com/y282845/emoticons/cool.gif.3bcaf8f141236c00f8044d07150e34f7.gif

 

[Ali1 10+ year member]

exactly

 

[audiolife 5,000+ posts]

if you really want to learn get a dmm that has a wave function(that will put readings into a wave format). start off on the output of the alt then after the battery, then by the amp i think it would become obvious what is happening.

 

[helotaxi 5,000+ posts]

if you really want to learn get a dmm that has a wave function(that will put readings into a wave format). start off on the output of the alt then after the battery, then by the amp i think it would become obvious what is happening.

I'm assuming that you're referring to the capacitance of the battery acting to filter out the ripple voltage from the alt?

As far as an alt providing 500A, no normal system draws that kind of current. For a pure comp system, the alt becomes largely irrelevant during the burp as the battery bank becomes the primary current supply.

For a realisitc daily system, the alt SHOULD be the primary source of current and the battery there to back up the alt when the demand exceeds what the alt is currently putting out. The maximum capacity of the alt doesn't need to be exceeded for the battery to play a part. As hinted at above the battery will react faster to transient demands than the alt and the battery can act as a buffer to soften a transient voltage drop until the alt catches up.

For a daily system, a single good battery should provide more than enough reserve capacity. Adding a second battery shouldn't be necessary, as the alt should be the source of power for the car. Remember that the alt has to replace any energy drawn from the battery eventually so regularly exceeding the alt's capacity and relying on the battery to pick up the slack is a sure recipe to kill the battery and bun up the alt. Adding more batteries won't help this situation either as it doesn't diminish the amount of power that the alt has to replace and it also can make the siuaition worse because multiple batteries wired in parallel will draw more current while recharging than a single battery.

The real bottom line is that it isn't possible to to simply say that if you have X amount of amp power and the alt is rated for Y then you need to add Z to the car to make sure that you don't have any electrical problems simply because every system, every car and every user is different and what works for one may not work at all for another.

 

[audiolife 5,000+ posts]

a 200 amp alt isn't a 200 amp alt all the time regardless of the load on it (it has to spin @ xxxx rpm to do that and its alot less than 200 amps at idle) if you listen to music either alt (stock or hi output) will use the battery as a buffer regardless. under normal conditions a 80-100 amp alt will have time to adequately charge up 2 batteries if you aren't constantly beating on your system. not only that but i think i would rather have that extra reserve of the battery for when i wanted to blast my system (which is usually done while parked or driving really slow when your super alt isn't quite so super). also when you add a battery to the back with the right sized wire/wires from the front battery all of the sudden something else happens......more than likely you will have less voltage drop AT the amplifier which does what with our "buffer"? (which it is more than a buffer and acts more than a buffer when needed i would fully call it usable reserve lol)

i wont argue that a high output alt wont make you "louder" (by a few tenths usually anyway) but in situations where you beat on your system to show it off or to see what it can do (you probably aren't going to do that in all likely hood at 50 miles an hour as i dont know maybe it would take away from some of the effect of it lol) an extra battery can defiantly stop your amp from going into protection or worse. some of your high output alts actually put out less power at idle than a factory alt...and if it puts out a crap load of current at really low rpm its eating up hp in use and it will in all probability have some durability issues in its own right.

i have had less problems with modest systems that simply had an extra battery than i have had with high output alts that were professionally installed also imo its sort of a waste to have a HO alt without the extra battery...after all now you would have the charging capacity in which to work with.

heck in 1990-92 ppi told me to get an extra battery after they fixxed my 2200 AM the second time lol i went one step beyond that and got a dual 120 amp output alt and a deep cycle battery. at the time i had 2 4200's a 2150 and a 2200 in that car...worked great for a week at a time until i did the upgrade....