2nd battery...

[aaron7114 10+ year member]

So would just upgrading my current battery help any at all?

 

[audiolife 5,000+ posts]

it will help but you need to allow the system to recharge itself some. personally from your listening habbits i would do both alt and batt.

 

[spin dB 10+ year member]

If it was me I would think about exchanging the batt under the hood to a Kinetic HC 1800 or something like that. The discharge rate is a great deal higher and it is faster to recharge than a stock of the same amperage. I would also concider running a HC-800 near the amps, and if at all possible upgrade the alt and do the big 3 upgrade. Doing all this should help tremendously with voltage dip, depending on the current draw and the number of amps this should be able to stabalize the voltage to around 13 or 13.4vrms with the car running

 

[Thnking 10+ year member]

an amp wont blow if the voltage drops too low? lol they get hot and burn up magic puffs of smoke.

You’re telling me that an amp will burn up when voltage drops low...?

That’s absolutely ridiculous.

You do understand that excess VA burns up components in amps, not a lack of, lol.

plus the voltage drops you are talking about in a system are maybe .2 db at best in performance on average probably .1 on average.

Take an example; an amplifier is loading the circuit with 50amps, the efficiency is 70%, the voltage is 14.2V. Ignore other non-relevant losses.

That’s 497 watts.

The voltage drops to 13V, the efficiency drops to 60% (very realistic), the draw remains at 50amps…the number would probably change, but it’s dependant on power supply.

That’s 390amps. That’s a 120watt difference. Which is frequency dependant on SPL change, and VA drops will happen with every amp.

there are alot of amps that sell and get used that would take a monster of an alt to match with and we arent even talking about what the car needs. not very many people get amps this big to listen to music in a traditional sense either at some point i bet they throw in shine sweeps and specific hertz tones to some heavy bass music just to see what it will do. there are tons of subs out there that can take over 1000 watts to push. re xxx ,adire brahma, l7's solox's, i see w7's with over 1000 watts each on them plus alot more subs than that. again we arent talking even about the rest of the system or again what even the car needs.hell i can think of 3 cars in my little speed bump of a town that qualify for what im talking about. a good 240 amp + alt and getting it installed right isnt an inexpensive thing to do. when i talked to OG they said the 240 amp alt i have is good for a system from 2500-3000 watts WITH a second battery.

Are you reading what typing? Just because someone has 4x 1000watt subs with 4x 1200watt amps, doesn’t mean they are going to be driving loading their circuit with 4800watts. Just because someone has a 1000watt sub doesn’t mean that the average load on the system from a 1000watt amplifier will be 1000watts. Who cares what the voltage drops to with sweeps…this isn’t an argument on what happens when someone overloads their alternator. Your perception on people and how large of a system they have and how much they load their electrical is way off for most people. The fact is if the person can match load to alternator output, do it. They don’t need a 2nd battery. If someone can’t then it’s time to use a bank(s). Most people on this forum and on all other car audio forums can match their alternator to their load.

 

[spin dB 10+ year member]

If it was me I would think about exchanging the batt under the hood to a Kinetic HC 1800 or something like that. The discharge rate is a great deal higher and it is faster to recharge than a stock of the same amperage. I would also concider running a HC-800 near the amps, and if at all possible upgrade the alt and do the big 3 upgrade. Doing all this should help tremendously with voltage dip, depending on the current draw and the number of amps this should be able to stabalize the voltage to around 13 or 13.4vrms with the car running

I would do the Big 3 upgrade with 1/0 awg wire with a large thread count this will help even further. I would also concider upgrading the alt so that it will be able to adequately support the batteries and the voltage dip should be under control. You have to remember that you are not going to take care of Voltage Dip entirely, you will always have a noticable drop, either with a DMM or when you lights dim, you will know. All you can hope to do is stabalize it the best you can, and doing everything here will to just that!! As for the arguements between some of the other posters I would research those on your own and come to your own conclusions, both have some good points but it can get confusing if you don't completely understand!

 

[audiolife 5,000+ posts]

ok lets run a 1000 watt amp at 11-10.5v rest and see what happens ......lmao i have cooked amplifiers like this before be it not in 10 years but i have. when do most people turn up their systems? show me a car show or even the local parking lot where anyone revs their engine to show off their system better yet show me an alt that would do full or near full power at idle for daily use. weither you admit it or not the system will rely on the battery/batteries at some point. about 80% of the car audio buffs i know go cruising and park their cars. yes, some let their cars idle when they are listening but if you are at the point where the amps are pulling alot at idle that leaves less for other parts of the system and the car. my point wasnt a 1000 watt amp is always a 1000 watts the point was what about the rest of the set up + the car ....... never once did i say the alt isnt important but i dont know of any that would "stand alone" to run an entire system as if it would/could it would eat up alot of gas/hp and in all probability have a serious lifespan issue . i couldnt count how many times all we did was get a simple alt rewind (usually just a 15-30 amp increase) and slap in an extra battery and go never had an issue in doing that in a typical set up (in fact i have done/helped do it without an alt upgrade with pretty much same result). you argue about what an amps load is or could be but at the same time by a known percent your alt is only doing 50% power or so at some point on your trip unless you turn up and down your audio system to the amount of rpms your engine is doing (in a daily driver i have never seen anyone do that)....and most high output alt places i know of will always recomend a good battery to either add to or go with (under the hood) this goes back to lestech(17 yrs ago) to ohio generator....

 

[knukonceptz 10+ year member]

You’re telling me that an amp will burn up when voltage drops low...?That’s absolutely ridiculous.

You do understand that excess VA burns up components in amps, not a lack of, lol.

Lower voltage means more amps are drawn by the power supply. Each MOSFET is rated by amps, drawing too many amps over loads the power supply. When the power supply is overloaded a MOSFET goes poof.....

Are you reading what typing? Just because someone has 4x 1000watt subs with 4x 1200watt amps, doesn’t mean they are going to be driving loading their circuit with 4800watts. Just because someone has a 1000watt sub doesn’t mean that the average load on the system from a 1000watt amplifier will be 1000watts. Who cares what the voltage drops to with sweeps…this isn’t an argument on what happens when someone overloads their alternator. Your perception on people and how large of a system they have and how much they load their electrical is way off for most people. The fact is if the person can match load to alternator output, do it. They don’t need a 2nd battery. If someone can’t then it’s time to use a bank(s). Most people on this forum and on all other car audio forums can match their alternator to their load.

First, the watt rating of a sub has no relevance at all. I will agree with you that people's perception of what they draw on a daily basis is much lower then the systems maximum potential. Reason for this *Music is dynamic* Now then if they are using test tones they will see near full potential. I would guess the majority of the guys out there with one amp have something drawing 80-120A max so on a daily basis thats 50-80A something that wont need a HO Alt or extra battery.

Now then, guys buying 1/0 and having two and three amps are very capable of drawing 150A with music and 300A with test tones. Maxxsonics released an amp capable of 1000A draw (yes a single amplifier) it has 4 sets (as in power/ground x 4) of 2 gauge inputs - please see what they used to test the beast:

http://www.maxxsonics.com/index_images/PAS_Maxximus.pdf

Two modified 100A power supplies and 4 batteries - yet maintain 14V when, by your thinking, a battery only discharges below 12.8V. Now, you are obviously very intelligent person and know a lot of about alternators, but the audio industry seems to be throwing a curve ball your way. I do not have the complete and total understanding to explain it as to the actual physics involved - adding batteries will maintain your voltage above even 12.8V during a short term. And this is why I believe this:

Using a 120A alternator in daytime on a 150A stereo draw, at idle 14.4v from the alternator is also placing a surface charge on the fully charged battery so that it to is operating at 14.4v (its part of the system) Now then since the music is dynamic and very fast the amps require power very quickly. If the demand is 150A and the alt is making 120A (assuming we no longer at idle....lol ) in that split second the battery needs to displace the difference of 30A - now is that 30A 12.8V, no its part of what ever is out there most likely a high 13.x number. I am sure there is some direct relation and method to determine this, but we need more constants in my story for that. I will agree at some point a larger front battery will have little assistance.

However, we all seem to forget one thing in all our babble - RESISTANCE - At 12V with a 200A load on 1/0 cable you will have voltage loss of almost 1 volt at the rear. You put a battery in the rear (of the same size as the front battery) and you have eliminated a very real loss. Again it is a surface charge at higher voltage, but the amperage will still come from that rear bank because of lower resistance. An alternator cant compensate for the loss due to cable length travel - unless you mount the amp under the hood

I personally competed for over 2 years, using 5 batteries, (4 in the rear hatch) - no Isolators or solenoids with a 90A ford Alternator with Transpo external regulator. At a show - idle set at 15.1V I could play 30 seconds and stay in the 13V range with over 300A draw (4 sub amps - each drawing 80-90 amps on a test tone) Using a isolator in car audio is pointless, you lose 0.5V just connecting one up, the added reserve is much more valuable.

Anyone try the jumper cable test (second car off //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif obviously)

The average car will benefit from the second battery for the simple fact it will help decrease voltage spikes which will effect the output of the amp by altering efficiency. Even if the system can draw more then the alternator at its *dynamic* power because as stated - one person can not possibly listen to the radio 100% of the time** the car is running. While your on your phone- the alternator is recharging the battery. Ordering Taco Bell - the alternator is recharging the battery. Waiting for the cop to write the ticket, the alternator is recharging the battery. Changing tracks - the alternator is recharging the battery. Pretending to listen to your GF, the alternator is recharging the battery.

**At max volume

 

[AJ²06 5,000+ posts]

^^

Wut he said... //content.invisioncic.com/y282845/emoticons/word.gif.64b12e39f936af3b4fff38a1c0bd0244.gif

 

[Ali1 10+ year member]

so i should thank the police for pulling me over, so i my alternator can keep up, making my system louder for everyone to hear.....

 

[audiolife 5,000+ posts]

First, the watt rating of a sub has no relevance at all. I will agree with you that people's perception of what they draw on a daily basis is much lower then the systems maximum potential. Reason for this *Music is dynamic* Now then if they are using test tones they will see near full potential. I would guess the majority of the guys out there with one amp have something drawing 80-120A max so on a daily basis thats 50-80A something that wont need a HO Alt or extra battery.

point i was making about power is of those cars i know of everyone has the bass cds with the tones sweeps and the songs with the really long riffs. also being with kinetik last year (at finals,nopi, carl casper) and other shows i have seen amps go poof in less than 6 seconds during burps, also of those i seen go poof most werent that large of a set up. watching their voltage meters drop past 10v is a bit of a clue to what happened, and it doesnt take alot of time to get the ill effects from haveing low voltage.....when you press an amp like that its neither good for the amp nor the speakers....i would rather be safe than sorry as doing it right the first time saves money on equipment and time swapping the smoked equipment out .....alot of people will try to over look upgrading their car electrical in favor of getting larger amps. when you upgrade your car electrical it doesnt come and go like equipment does you can leave it in or add too it as your system grows or changes. much like using the right wire and propper accessories....you buy right the first time its one of those things that wont need changed as your system does.

 

[memphis10 10+ year member]

if i buy a nice hc 2000 will it make sense to jsut leave my stock battery in and install the hc elsewhere or will it be strong enough to replace my stock battery if i install an alternator

 

[audiolife 5,000+ posts]

depending on your set up if its modest you can put the 2000 back by your amps . i dont know your car or set up but if your alt works good and you are 2000 watts or under shouldnt be a problem at all

 

[Thnking 10+ year member]

Lower voltage means more amps are drawn by the power supply. Each MOSFET is rated by amps, drawing too many amps over loads the power supply. When the power supply is overloaded a MOSFET goes poof.....

Actually, the FET has a VA rating. What you’re saying is incorrect as well, and a different scenario than the voltage being low. If the supply voltage were to drop, yes current in a regulated amplifier would increase, but there is a limit. It doesn’t exceed whatever limit the amp manufacturer has designed for the particular PS.

If there is an UNDERVOLTAGE situation in the PS input, typically any modern amplifier goes into protection. If it doesn’t then a FET or MOSFET can fail to turn on, causing damage.

Like I said above, low voltage wouldn’t damage an amplifier, under voltage is typically protected against, and technically doesn’t damage an amplifier but rather makes the amplifier’s components not operate properly.

Two modified 100A power supplies and 4 batteries - yet maintain 14V when, by your thinking, a battery only discharges below 12.8V. Now, you are obviously very intelligent person and know a lot of about alternators, but the audio industry seems to be throwing a curve ball your way. I do not have the complete and total understanding to explain it as to the actual physics involved - adding batteries will maintain your voltage above even 12.8V during a short term. And this is why I believe this:

Using a 120A alternator in daytime on a 150A stereo draw, at idle 14.4v from the alternator is also placing a surface charge on the fully charged battery so that it to is operating at 14.4v (its part of the system) Now then since the music is dynamic and very fast the amps require power very quickly. If the demand is 150A and the alt is making 120A (assuming we no longer at idle....lol ) in that split second the battery needs to displace the difference of 30A - now is that 30A 12.8V, no its part of what ever is out there most likely a high 13.x number. I am sure there is some direct relation and method to determine this, but we need more constants in my story for that. I will agree at some point a larger front battery will have little assistance.

However, we all seem to forget one thing in all our babble - RESISTANCE - At 12V with a 200A load on 1/0 cable you will have voltage loss of almost 1 volt at the rear. You put a battery in the rear (of the same size as the front battery) and you have eliminated a very real loss. Again it is a surface charge at higher voltage, but the amperage will still come from that rear bank because of lower resistance. An alternator cant compensate for the loss due to cable length travel - unless you mount the amp under the hood

I personally competed for over 2 years, using 5 batteries, (4 in the rear hatch) - no Isolators or solenoids with a 90A ford Alternator with Transpo external regulator. At a show - idle set at 15.1V I could play 30 seconds and stay in the 13V range with over 300A draw (4 sub amps - each drawing 80-90 amps on a test tone) Using a isolator in car audio is pointless, you lose 0.5V just connecting one up, the added reserve is much more valuable.

Anyone try the jumper cable test (second car off //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif obviously)

The average car will benefit from the second battery for the simple fact it will help decrease voltage spikes which will effect the output of the amp by altering efficiency. Even if the system can draw more then the alternator at its *dynamic* power because as stated - one person can not possibly listen to the radio 100% of the time** the car is running. While your on your phone- the alternator is recharging the battery. Ordering Taco Bell - the alternator is recharging the battery. Waiting for the cop to write the ticket, the alternator is recharging the battery. Changing tracks - the alternator is recharging the battery. Pretending to listen to your GF, the alternator is recharging the battery.

**At max volume

I don’t see how a surface charge, which is merely a not completed state of charge, could increase potential, the actual surface charge wouldn’t increase past he batteries full SOC voltage (12.whatever). The potential may be a little higher than the manufacturer specs, but that’s normal.

I’m sure that what would happen in a situation where the alt was underrated for the load, is that the duty cycle of the music was high enough to take an average reading of 13V, while the actual voltage was dipping well below that number (or at least low enough to allow the batteries to discharge enough). 2.1V is a large dip for a daily driver, I know I wouldn’t tolerate that.

The truth of the matter is that a 2nd battery or 3rd or 4th or etc… has no added benefits over a properly sized alternator, and does start causing problems when installed (unequal resistance points, added equiv. impedance, doesn’t discharge until the voltage drops). It makes no sense to add one when you don’t need to.

 

[audiolife 5,000+ posts]

lol i have seen amps make nice smoke signals even with protection in fact i have even seen them go into protection and not come back out ....point is mute there is no 100% fail safe for that...

 

[knukonceptz 10+ year member]

Actually, the FET has a VA rating. What you’re saying is incorrect as well, and a different scenario than the voltage being low. If the supply voltage were to drop, yes current in a regulated amplifier would increase, but there is a limit. It doesn’t exceed whatever limit the amp manufacturer has designed for the particular PS.If there is an UNDERVOLTAGE situation in the PS input, typically any modern amplifier goes into protection. If it doesn’t then a FET or MOSFET can fail to turn on, causing damage.

Like I said above, low voltage wouldn’t damage an amplifier, under voltage is typically protected against, and technically doesn’t damage an amplifier but rather makes the amplifier’s components not operate properly.

Yes, they do operate at VA, and the number of amps draw is relative to the voltage - thus why capacitors are in the amp to smooth out voltage for the power supply.

You clearly have never seen an amp go bad, because obviously something is exceeding the manufactured "design". Low voltage will keep an amp from turning on initially. Once that sucker is on and working hard, the protect circuit will not always save you especially when driving an amp at a low impedance.

I don’t see how a surface charge, which is merely a not completed state of charge, could increase potential, the actual surface charge wouldn’t increase past he batteries full SOC voltage (12.whatever). The potential may be a little higher than the manufacturer specs, but that’s normal.

I’m sure that what would happen in a situation where the alt was underrated for the load, is that the duty cycle of the music was high enough to take an average reading of 13V, while the actual voltage was dipping well below that number (or at least low enough to allow the batteries to discharge enough). 2.1V is a large dip for a daily driver, I know I wouldn’t tolerate that.

The truth of the matter is that a 2nd battery or 3rd or 4th or etc… has no added benefits over a properly sized alternator, and does start causing problems when installed (unequal resistance points, added equiv. impedance, doesn’t discharge until the voltage drops). It makes no sense to add one when you don’t need to.

As I stated above, amperage is coming from out of the battery in the 13-14V range - there is no other explanation for it, otherwise everytime a load exceeded the ALT we'd all drop instantly to 12.8V and that is not what happens. But just for the sake of arguement - even if it isnt - the second battery in the rear WOULD strengthen the charging system by adding reserve and maintain a 12V load longer then a single battery and lower voltage loss from resistance in the cabling. 12V is what the power supply will and can work on. My whole point is that not everyone can get a HO Alt for there car - either they do not fit or the customer can not afford it. Adding one would be great if you can, a second battery however is atleast 1/2 the price and will certainly provide a benefit to anyone chossing that option.