rpms drop at idle help?

[fireball75427 10+ year member]

right and wrong at the same time... re-read what i said...
low voltage is not the cause of alternator failure. increased demand from the charging system(IE excessive current draw) can cause alt failure, but seeing as how the alternator is the originating source of the voltage, i dont think it is likely that it will harm itself...

heat is the enemy of all electronics. extra current = extra heat. extra current needed = alt works harde. alt working harder = increased heat output. increased heat leads to alt failure.

but you are on the right track with it, saying that low voltage is going to kil an alt is kind of a blanket statement. re-wording it to say "the excessive current draw ******* my voltage down is going to harm my alt" would be more corrector //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

well i just dont want to get all complicated and detailed for ppl who dont understand. yes ur right and totally agree with you. the electronics is the cause of the low voltage and will be the cause of an alternator failure. all i know is he needs a bigger alternator or it could cost him more then he expects from replacing not only his alt but his amp, subs, wutever he has hooked up. just spend the 150-200 wutever it costs for the 200 amp alternator for the car to be on the safe side. especially since car audio is addictive and you always find a way to upgrade.

 

[draarong2004 10+ year member]

dangerous advice man... low voltage can kill electronics...

if his voltage drops that much, there's something wrong in the car, and the battery will die LONG before anything is damaged.

sounds like u need a bigger alternator(200 amp). the stock one is prob around 120-130. yes u can buy a stiffening capacitor but my experiences wit caps tell me its a waste of money when u can just buy a bigger alternator for the price and does a lot better job. most likely ur lights dim if u havent noticed.

i HIGHLY doubt his stock alternator is that big, i've got a 130 amp in my truck, i'm running more power, and mine don't go down like that unless i'm at full tilt with all the lights/heater on. i think a 130 amp would be an upgrade for him, if i'm not mistaken, those cars came stock with 70 amp alternators.

 

[hoss 5,000+ posts]

if his voltage drops that much, there's something wrong in the car, and the battery will die LONG before anything is damaged.

you sure about that? you care to explain to me why my amp caught on fire before the battery died? or do you want me to go ahead and explain it for you?

the voltage is a combination of two sources, voltage coming from the battery(reserve power), and voltage coming from the charging system(A.K.A. the alternator, A.K.A. power on tap). if the voltage dips lower than the battery can support, it will drain it from the alternator, if the alternator cant keep up, the voltage goes into the danger zone. while this isnt good for the battery, it is not going to kill it in the short term. any time you present low voltage to a battery, it isnt going to be healthy for it, but as long as you dont keep it in a low voltage environment, it will be ok. if you keep a battery at a low voltage for any extended amount of time, its not going to come back to the voltage its supposed to be at.

however, if you present a low voltage situation to the electronics, even for short periods of time it can cause harm. lets say, for example, you have a car stereo that is made to be run at 12v, but your charging system cant keep up and you are drawing it down to ~9-10v. the input side of the amplifier is going to be working overtime trying to feed the output side of said amplifier. with the input side working overtime, it causes heat. heat causes parts to become inefficient, inefficiency leads to them working even harder, which leads to more heat, which leads to dead electronics. the battery on the other hand while its not happy at what you are doing to it, once you stop and it breathes a sigh of relief because it has current again, can charge back up, and go on about its business.

low voltage is going to kill your electronics before it hurts the battery. so saying that you will be fine because your battery will keel over before your stereo will is a large crock of shit //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

so now, if you have any info to back up your claim, i really would like to know why my amplifier caught on fire before my battery even thought about having a problem //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[thatsgonnahurt 10+ year member]

the voltage is a combination of two sources, voltage coming from the battery(reserve power), and voltage coming from the charging system(A.K.A. the alternator, A.K.A. power on tap). if the voltage dips lower than the battery can support, it will drain it from the alternator, if the alternator cant keep up, the voltage goes into the danger zone.

however, if you present a low voltage situation to the electronics, even for short periods of time it can cause harm. lets say, for example, you have a car stereo that is made to be run at 12v, but your charging system cant keep up and you are drawing it down to ~9-10v. the input side of the amplifier is going to be working overtime trying to feed the output side of said amplifier. with the input side working overtime, it causes heat. heat causes parts to become inefficient, inefficiency leads to them working even harder, which leads to more heat, which leads to dead electronics. the battery on the other hand while its not happy at what you are doing to it, once you stop and it breathes a sigh of relief because it has current again, can charge back up, and go on about its business.

my response:

the alternator supplies power for the vehicle when the engine is running. when the alternator cant keep up with the demands of the electrical system and its voltage drops below the battery floating point of 12.66 volts then and only then does the battery supply power. at all other times it appears as a load to the alternator and the degree to which depends on its state of charge.

now, about the amplifier low voltage myth. if an amplifiers voltage is too low they simply will not work. if the voltage drops low but still within the specs of the amp it will work more efficiently. it will not draw more current to maintain its output with a reduction in input voltage. the less voltage the amp sees the less current it draws. less current equals less heat. so with lower input voltage amplifiers actually run cooler. this has been demonstrated by richard clark. you can read more on carsound.com

 

[regal8r 5,000+ posts]

Thanks alot, its still a good idea to upgrade my Big 3 tho right? I was told by my local shop not to upgrade the Big 3 since im only running 4 awg power wire is this true or should i go ahead and do it anyway?

what can it hurt...seriously???

on my car with a 105a alt and a bx2005d running at 1 ohm, my rpm's will drop about 300 rpm in extreme cases at idle. i have tested voltage at my battery with system playing at full tilt and it never dropped below 13.8v. if u have a dmm, just put it across the battery in the dc voltage setting and see what u get for voltage with ur system on. if it says above 13.5 with car running, u should be fine.

 

[hoss 5,000+ posts]

now, about the amplifier low voltage myth. if an amplifiers voltage is too low they simply will not work. if the voltage drops low but still within the specs of the amp it will work more efficiently. it will not draw more current to maintain its output with a reduction in input voltage. the less voltage the amp sees the less current it draws. less current equals less heat. so with lower input voltage amplifiers actually run cooler. this has been demonstrated by richard clark. you can read more on carsound.com

LMFAO!!! ok. whatever you believe, go for it //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

and as for it being a myth... sorry man, its a proven fact. not all amplifiers have protection circuits, so they arent just going to cut themselves off...

you cant always depend on something else to save your ***. i bet that you believe that condoms are a 100% sure way from getting a chick pregnant too //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

 

[thatsgonnahurt 10+ year member]

check it out if you like, its a discussion on input voltage to amps and overheating post #16 for startershttp://www.audiogroupforum.com/csforum/showthread.php?t=9590&page=2&highlight=11.5+volts+overheating

post by rc showing input voltage versus current post #182http://www.audiogroupforum.com/csforum/showthread.php?t=5010&page=19&highlight=ground+currents

 

[hoss 5,000+ posts]

without reading all of that i can already tell you, i have witnessed first hand what low voltage can do... and within reading the first few repolies, people have already said what i have witnessed.

low input voltage leads to more input current, leads to the input side of the amp working harder to try to compensate for what the output side of the amp is demanding of it. the output side of the amplifier is demanding a certain amount of power from the input side, and when the input side is seeing less voltage, it is going to compensate by drawing more current. now since the input side of the amp is having to work way harder than it would be if the voltage was at the point it should be, it is going to heat up, become less efficient, yadda yadda yadda.

if an amp has protection on it, whether it be thermal, under voltage, low impedance protection, it will shut off. if it doesent have said protection, it will keep over working itself until something finally goes internally. and like alot of electronics, it could be a chain reaction. one thing goes, leading another member to fail, leading something else to explode, and so on down the line.

remember, im not speaking on behalf of what i read in a book, what i read on the internet, what someone has told me, or according to physics... im talking in the real world, that i have witnessed. i was there, the trunk of my car was shooting flames. at the time, the only flaw in my system was that my amp was drawing current down to about 7-9v. the battery and charging system was fine. the member that failed, was the amplifiers input section which overheated. no repairs were made to the output side of the board.

 

[thatsgonnahurt 10+ year member]

hoss, i have no doubt your amp caught on fire due to overheating. ecessive current leads to overheating which leads to fire. what input voltages did your amp see?

 

[draarong2004 10+ year member]

you sure about that? you care to explain to me why my amp caught on fire before the battery died? or do you want me to go ahead and explain it for you?
the voltage is a combination of two sources, voltage coming from the battery(reserve power), and voltage coming from the charging system(A.K.A. the alternator, A.K.A. power on tap). if the voltage dips lower than the battery can support, it will drain it from the alternator, if the alternator cant keep up, the voltage goes into the danger zone. while this isnt good for the battery, it is not going to kill it in the short term. any time you present low voltage to a battery, it isnt going to be healthy for it, but as long as you dont keep it in a low voltage environment, it will be ok. if you keep a battery at a low voltage for any extended amount of time, its not going to come back to the voltage its supposed to be at.

however, if you present a low voltage situation to the electronics, even for short periods of time it can cause harm. lets say, for example, you have a car stereo that is made to be run at 12v, but your charging system cant keep up and you are drawing it down to ~9-10v. the input side of the amplifier is going to be working overtime trying to feed the output side of said amplifier. with the input side working overtime, it causes heat. heat causes parts to become inefficient, inefficiency leads to them working even harder, which leads to more heat, which leads to dead electronics. the battery on the other hand while its not happy at what you are doing to it, once you stop and it breathes a sigh of relief because it has current again, can charge back up, and go on about its business.

low voltage is going to kill your electronics before it hurts the battery. so saying that you will be fine because your battery will keel over before your stereo will is a large crock of shit //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

so now, if you have any info to back up your claim, i really would like to know why my amplifier caught on fire before my battery even thought about having a problem //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

how can you prove that you had low voltage going to your amplifier? were you able to take a dmm to the battery while the car was on fire? did you have a "live" voltmeter in your dash somewhere......then no you can't prove it, and any amp that doesn't have a thermal overload wasn't worth much to begin with if it "caught on fire" because of heat. and if your voltage was dropping that low, your amp would've actually shut off, there's a reason why it requires a 12 volt turn on lead, a normal amp will actually shut off when that goes below 10-11 volts //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[hoss 5,000+ posts]

how can you prove that you had low voltage going to your amplifier? were you able to take a dmm to the battery while the car was on fire? did you have a "live" voltmeter in your dash somewhere......then no you can't prove it

ok, lets start here. do you need to have a voltmeter to know that you are getting low voltage? no, any person with a shred of intellect (this clearly rules you out...) can notice tell tale signs that their voltage is dropping. you can look at the lights in the car, if you notice them dimming profusly, guess what, your voltage is probably pretty low. and yes, i did test it with a DMM at one point, and guess what, my assumption was accurate, i had low voltage. holy ****ing christ! what a novel concept.

and any amp that doesn't have a thermal overload wasn't worth much to begin with if it "caught on fire" because of heat.

if you think that the Tru H-series amps arent that great, then keep thinking that. or any SPL oriented high output amps designed to be run at low impedances and generate alot of heat for that matter. just because a company doesent give the amp a protection circuit doesent mean anything about its quality.

and if your voltage was dropping that low, your amp would've actually shut off, there's a reason why it requires a 12 volt turn on lead, a normal amp will actually shut off when that goes below 10-11 volts //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

dude... the car was at 7v, the HU was still putting out 12v... think outside the box here, the car has voltage, the HU has its own voltage, car voltage changes, HU stays the same, amps stay powered...

now, are you done being wrong, or would you like me to correct you some more? //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[ibanender 10+ year member]

how can you prove that you had low voltage going to your amplifier? were you able to take a dmm to the battery while the car was on fire? did you have a "live" voltmeter in your dash somewhere......then no you can't prove it, and any amp that doesn't have a thermal overload wasn't worth much to begin with if it "caught on fire" because of heat. and if your voltage was dropping that low, your amp would've actually shut off, there's a reason why it requires a 12 volt turn on lead, a normal amp will actually shut off when that goes below 10-11 volts //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

He can prove it. How, because I personally have tested his vehicle! If you have the stereo on and you stop at a traffic light and your car shuts off after it idles funny, thats low voltage. The amp actually caught fire while the car was off and he wasn't in it. How do I know? It could be because I was on the phone with him when he got back to his car with tools to see why it quit playing. Thermal protection isn't active when the amp isn't turned on, and if you knew ANYTHING about those amps, you'd know they do have a thermal shut off and thermal monitoring because the fans will actually turn on to cool the amp when the remote wire has no power on it. Yes, thats right, the amps fans run to cool it BEFORE YOU TURN IT ON.

Now that we've established that amp isn't a normal amp, can you think of more amps that just die instead of shutting off? I certainly can. USAmps wont shut off, they'll die, MA Audio wont shut off, they'll die. The sudden lack of voltage will make them shut off, the constant borderline voltage strains the power supply which is what dies.

 

[draarong2004 10+ year member]

i'd love for someone to make sense of the hu putting out a 12v solid signal if it isn't even getting 12 volts, if you could explain that one it'd make everything fall into place, please don't forget your resources //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[draarong2004 10+ year member]

He can prove it. How, because I personally have tested his vehicle! If you have the stereo on and you stop at a traffic light and your car shuts off after it idles funny, thats low voltage. The amp actually caught fire while the car was off and he wasn't in it. How do I know? It could be because I was on the phone with him when he got back to his car with tools to see why it quit playing. Thermal protection isn't active when the amp isn't turned on, and if you knew ANYTHING about those amps, you'd know they do have a thermal shut off and thermal monitoring because the fans will actually turn on to cool the amp when the remote wire has no power on it. Yes, thats right, the amps fans run to cool it BEFORE YOU TURN IT ON.
Now that we've established that amp isn't a normal amp, can you think of more amps that just die instead of shutting off? I certainly can. USAmps wont shut off, they'll die, MA Audio wont shut off, they'll die. The sudden lack of voltage will make them shut off, the constant borderline voltage strains the power supply which is what dies.

and if thats the case, and its well known that the amp won't shut off from low voltage, why don't you take precautions to stop that from happening, like getting something like this http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7539467807&category=4660

 

[hoss 5,000+ posts]

i'd love for someone to make sense of the hu putting out a 12v solid signal if it isn't even getting 12 volts, if you could explain that one it'd make everything fall into place, please don't forget your resources //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

because power doesent run straight through the HU... the HU creates the 12v turn on signal, it generates a 12v signal, with extremely low current. the 12v does not simply pass through the HU and go to the remote wire, its part of what the unit itself does. my particular head unit at the time was capable of three 4v pre-outs, and 4 channels of 45watts of power. do you think that these 4v pre-outs and 45 watts of power were generated by the cars 12v system? //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif . remember when i said think outside the box? you are still stuck in it. the HU generates that 12v signal, it is completely independant of the cars 12v charging system. do you think that your amplifier running your speaker is putting out 12v? no, its probably putting out well over 12v, with less current going out of it than is coming into it. while it is dependant on the cars electrical system, it still runs INdependantly.

and if thats the case, and its well known that the amp won't shut off from low voltage, why don't you take precautions to stop that from happening, like getting something like this http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7539467807&category=4660

because we didnt think it to be as serious a problem as it actually was. and i, for one, never knew of such a device. but hey, hindsight is 20/20. i lived, i learned(something you should try //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif )