Subs draining TOO much power...

[botchla90393]

hey guys,

Last night i was on a cruise and had the system cranking for about 3 songs while the car was idling in traffic....the head unit shut off randomly while playing it and the interior and exterior lights became very very dim even when nothing was playing...i shut it off straight away when it came back on to see if my lights would brighten up more, and they didnt. so in an attempt to make my voltage rise, i revved the engine, nothing past 2500rpm because my water temp was already rising really really quickly until the thermostat kicked in and brought it back down.

my system is:
4 x rockford fosgate punch splits
1 x alpine mrp-f450 amp (8 gauge wire)
2 x alpine type s subs making 600RMS
1 x alpine mrp-m850 amp (4 gauge wire)
head unit - alpine 9881

the car (vt commodore) has never done anything like this before and i have played songs for a longer period of time and nothing would happen....im just worried that the next song i will turn up will do some more damage....

do any of you know what might have caused the lights to stay dimmed AND make the water temp rise?? what i could do to fix this problem???

thanks in advance

[Tasmaniak]

how old is your battery?

[commsirac]

hey guys,

Last night i was on a cruise and had the system cranking for about 3 songs while the car was idling in traffic....the head unit shut off randomly while playing it and the interior and exterior lights became very very dim even when nothing was playing...i shut it off straight away when it came back on to see if my lights would brighten up more, and they didnt. so in an attempt to make

Did things revert to normal when you shut the stereo down.?
for the head unit to switch off, it indicates that the voltage dropped very low, and along with the dimming of your lights it suggests the presence of a very large fault creating currents that are most likely due to short circuits.

Either the problem could be in the wiring that goes to your amps(fuse protected?) or an internal problem within the amps. Id try one amp at a time 1st and take it from there.

From what you describe it is not a battery problem.

[StoneX]

Don't play the stereo loud at idle... That's how you kill things... The Alternator doesn't output much current at idle and big current draws will drop the voltage too low for products to work properly. Amplifiers can die from this.

Have your alternator and battery checked by an auto elec. They should do it free of charge if they're a good guy, as it only takes a couple of mins.

[Luked]

With that gear you could calculate the load and then opt for a 1-2(circa) farad capacitor. Or run dual batteries with relay'd isolators off the ignition barrel.
Ensure everything is fused individually too to be safe

[botchla90393]

Did things revert to normal when you shut the stereo down.?
for the head unit to switch off, it indicates that the voltage dropped very low, and along with the dimming of your lights it suggests the presence of a very large fault creating currents that are most likely due to short circuits.

Either the problem could be in the wiring that goes to your amps(fuse protected?) or an internal problem within the amps. Id try one amp at a time 1st and take it from there.

From what you describe it is not a battery problem.

the battery is prob 2 years old which would need replacing soon...was looking at the optima deep cycle batteries but theyre quite pricey for a good battery.

things did revert back to normal once the head unit was swiched off, but not instantaneously. took about 3-4 minutes before all the lights 'clicked' back on properly. i revved the engine during this stage to try and re charge the battery more but it did nothing.

All fuses are intact and nothing blew. i dont really think it would be an amp problem because the head unit power dropped and thats why the music stopped....

thanks for the replys.

[Stretchomatic]

how big is the negative cable that grounds to the chassis from your battery terminal?

[botchla90393]

Don't play the stereo loud at idle... That's how you kill things... The Alternator doesn't output much current at idle and big current draws will drop the voltage too low for products to work properly. Amplifiers can die from this.

Have your alternator and battery checked by an auto elec. They should do it free of charge if they're a good guy, as it only takes a couple of mins.

so if i want to play music loud i have to rev the engine? lol....

and yeah ill get them checked.

[botchla90393]

how big is the negative cable that grounds to the chassis from your battery terminal?

the big 3 havent been touched....are they like 8 guage stock???

[Stretchomatic]

i dunno how much of a difference it makes but alot of the guys that do sound systems around here tell me my lights dim when bass hits because my negative cable isnt big enough.
kinda makes sense considering theres a 8 and 4 guage power and large ground cables from the amps earthing out to the chassis, so its gotta get back in somehow.

[botchla90393]

alrighty ill give that a whirl as well as investing in a new battery...see how that goes.

no one can explain the water temp rising though... :S

[Stretchomatic]

no idea man...has the temp risen since or often.

[botchla90393]

since then, nop. probably because im too chicken to turn up the volume again! haha

[commsirac]

things did revert back to normal once the head unit was swiched off, but not instantaneously. took about 3-4 minutes before all the lights 'clicked' back on properly. i revved the engine during this stage to try and re charge the battery more but it did nothing. .

I can only think of three possibilities here:

1. The large current draw continued after switching off the stereo
2. The regulator on the alternator took its time in switching to charge mode and or other problem in the alternator.

All fuses are intact and nothing blew. i dont really think it would be an amp problem because the head unit power dropped and thats why the music stopped.

What is the rating on the fuses ? Do the cables for the amps lead directly from the battery and how far are the fuses from the battery.
Indeed it may not be an amp problem, however, the head unit switching off is most likely evidence that the voltage dropped below 10V due to a large untypical current draw and certainly I wouldnt rule out the amps being the source of that.

[commsirac]

alrighty ill give that a whirl as well as investing in a new battery...see how that goes.

no one can explain the water temp rising though... :S

Is there something wrong with the battery? If not, id leave that last on your list of things to try.

no one can explain the water temp rising though... :S

Possibly the power to the electric fans was also affected too.

Loose fan belt would also cause poor water circulation and alternator performance. I doubt this would be your problem though as it would be doing a lot of squealing when the revs are increased.

[commsirac]

i dunno how much of a difference it makes but alot of the guys that do sound systems around here tell me my lights dim when bass hits because my negative cable isnt big enough.
kinda makes sense considering theres a 8 and 4 guage power and large ground cables from the amps earthing out to the chassis, so its gotta get back in somehow.

A lot of it would make its way back through the drive train and engine and through the -ve cable going from the block to the battery, however, as suggested, it would be prudent to have a substantial additionaly cable going from the -ve terminal of the battery to a good chassis earth at the front of the car.

[botchla90393]

I can only think of three possibilities here:

What is the rating on the fuses ? Do the cables for the amps lead directly from the battery and how far are the fuses from the battery.
Indeed it may not be an amp problem, however, the head unit switching off is most likely evidence that the voltage dropped below 10V due to a large untypical current draw and certainly I wouldnt rule out the amps being the source of that.

yes the power cables lead directly to the battery and there isnt any distribution blocks or anything like that used. the fuses are located merely inches from the battery and rated at 60A for both.

and i dont think id rule out my battery as it is pretty ****ty and old...i cant even play music with my car off otherwise the battery will drain within 1 minute of playing music....loud or not.

thanks for the replys

[kopper69]

You can roughly check the condition of your battery and charging circuit using nothing more than a $14 multimeter. If you dont have one, get one. Available from just about anywhere. Once you know how to use it you will save yourself a lot of trouble. Could be your battery, could be your alternator, could be a bad connection on the battery or alternator. Check all the connections, give them a pull and make sure they are all rock solid. Fix any that arent. Get the multimeter and let me know and we can run through testing to find your fault.

I always recommended replacing batteries at two years, simply because thats when their warranties expire. Battery companies know that the battery will last two years and if you replace it every two years you are pretty much sure that you will never have a problem because of the battery. If you do, its the car that is causing it. However, I see that some batteries are now offering a three year warranty, and so I would recommend three years from these batteries. How long they will last though depends on how they are treated. If you leave the lights on or stereo to the point that you cant start the car, you have done damage to the battery that will affect its capacity and life.

If you are sus of the battery, replace it. For something so critical is sad that some people simply refuse to blame it. Really, the cost isnt huge for the role that it plays. Its a starting point anyway. I wouldnt be too surprised if it was your alternator though from the problems that you are describing.

[SAV_117]

hahaah $14 mulitmeter mate if my tafe lecturer heard that hahaha i just bought a 500 dollar one i think its best to get battry and alternator at least checked first it takes 2 seconds even if its not them it rules them out

[commsirac]

and i dont think id rule out my battery as it is pretty ****ty and old...i cant even play music with my car off otherwise the battery will drain within 1 minute of playing music....loud or not.

thanks for the replys

Well, if the battery is that far gone it could cause problems.......how can you even start the car with it if wont power the stereo after a minute?

[immortality]

hahaah $14 mulitmeter mate if my tafe lecturer heard that hahaha i just bought a 500 dollar one i think its best to get battry and alternator at least checked first it takes 2 seconds even if its not them it rules them out

mate, a $500 meter is over kill for the home mechanic who is simply checking for voltage and and maybe some resistance stuff at best.

get a meter as suggested (couple weeks ago the local dicksmith had a deal, 2 meters for $16 ). then check the battery and charging circuit as suggested. definitly upgrade the battery to chassis link as the factory one is not up to the job (minimum 4gauge).

i'd ignore the water temp reading for now. if the system voltage dropped low enough to shut down the head unit the reading won't be totally accurate. your water temp will rise when sitting in traffic idling anyway. as long as the thermos kick in everything should be fine

[TheyDontWantMusic]

hahaah $14 mulitmeter mate if my tafe lecturer heard that hahaha i just bought a 500 dollar one i think its best to get battry and alternator at least checked first it takes 2 seconds even if its not them it rules them out

you're an idiot.

I work in electronics assembly, the most expensive meter we ever use, is about $300, and thats only because we need guarenteed accuracy!

for 99% of people, a $30 meter has more features than they'll ever even use, and an $8 meter will do everything they need.

[Tasmaniak]

you're an idiot.

I work in electronics assembly, the most expensive meter we ever use, is about $300, and thats only because we need guarenteed accuracy!

for 99% of people, a $30 meter has more features than they'll ever even use, and an $8 meter will do everything they need.

Almost...on newer model vehicles a cheap multimeter can cause more damage then good when look for certain wires. More expensive multimeter are high impedance and only put a very minute load on the circuit you are testing. Some cheaper models don't have that and close to only 20ohms on the circuit. In which case one wrong mood and the PCM/ECM/BCM can take the big sleep. When testing wires on aftermarket accessories its fine but after that, you need to be careful....for whats it's worth I paid close to a grand for my Fluke but thats because it's also an scope which I find a valuable tool from time to time...measure anything but definetly overkill for the average installer.

[TheyDontWantMusic]

Almost...on newer model vehicles a cheap multimeter can cause more damage then good when look for certain wires. More expensive multimeter are high impedance and only put a very minute load on the circuit you are testing. Some cheaper models don't have that and close to only 20ohms on the circuit. In which case one wrong mood and the PCM/ECM/BCM can take the big sleep. When testing wires on aftermarket accessories its fine but after that, you need to be careful....for whats it's worth I paid close to a grand for my Fluke but thats because it's also an scope which I find a valuable tool from time to time...measure anything but definetly overkill for the average installer.

no digital meters put that much of a load on things.

most are 20 megohms internal resistance.

analog meters may be that low, but I wasn't talking about a 1980's meter here.

[botchla90393]

how can you even start the car with it if wont power the stereo after a minute?

simple, only play music with the car on. otherwise, ill have to put up and bare the silence lol.

if i did get a new battery would i be able to play a song or 2 with the car off?? or would i need to run it just to be safe....

ill buy a multimeter and let you guys know wtf is up with it lol.

cheers