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severe voltage drop, bad alternator?


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sparkie 
Platinum - Posts: 2,061
Platinum spacespace
Joined: November 06, 2003
Location: Canada
Posted: November 09, 2006 at 7:01 PM / IP Logged  
The great thing about this site is you can learn new things even if you have been doing for a very long time like me. Someone once said that there is no such thing as a wrong answer, only a well supported answer.
sparky
astro88 
Copper - Posts: 195
Copper spacespace
Joined: December 01, 2003
Location: Canada
Posted: November 09, 2006 at 7:49 PM / IP Logged  
Well i rewired the subs to be at 4 ohms and it sucks big tim!
i need to do some upgrades cause i need more bass lol,i never bought a 1200w amp just to run 300w!
And still turning up the volume with this set up i get dimming,not really bad but still present,gonna have to look into a new alternator around 200amp.
Thanx everyone for youre advice.
sedate 
Silver - Posts: 1,173
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Joined: July 03, 2004
Location: Colorado, United States
Posted: November 09, 2006 at 7:58 PM / IP Logged  
wirewise wrote:
Feel free to argue all you like, but it will not change this fact.
I take your leave to argue. Sometimes I get scared on this board.
wirewise wrote:
Adding more or larger batteries is really only a band-aid for the additional load placed on the existing electrical system once it has exceeded the output of the alternator. Yes, it will appear to solve the problem at first, but eventually the system will fail.
Okay. I think I figured this guys current draw to be like.. factoring amp overhead, a solid 150amps. At a 105amp alt, i dunno, 25-50% of which goes to the vehicle proper..this does leave a rather enormous power deficit. Of course.. this rests on the obviously incorrect assumption that power draw will *always* be 150amps + what the vehicle needs. A *constant* pull of 200+ amps would of course overwhelm a stock alt backed by *any* amalgamation of batteries in short order. This is however, is not typical behavior of a monoblock amplifier. The nature of dynamic music would only require such output.. every.. I dunno.. sayy.. 1/2 of a second, every other second. So 75% of the time the alternator is *well* above what the system requires for optimum output.
SOOOO ... utilizing larger batteries... which, on the whole, net more or less what they release, and are less susceptible to interminent voltage drop-off than the stock SLI batteries, is a highly competetive solution to the original posters' problem.
"I'm finished!" - Daniel Plainview
stevdart 
Platinum - Posts: 5,816
Platinum spaceThis member has made a donation to the12volt.com. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spaceThis member consistently provides reliable informationspace
Joined: January 24, 2004
Location: Pennsylvania, United States
Posted: November 09, 2006 at 9:23 PM / IP Logged  
Huh.
Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
astro88 
Copper - Posts: 195
Copper spacespace
Joined: December 01, 2003
Location: Canada
Posted: November 09, 2006 at 9:29 PM / IP Logged  
Originally i had a dual 4 ohm L7 hooked to this amp with 600wrms coming from the amp i had no big dimming problems.
I put in the re's and loaded the amp down to 1 ohm and at first it was pumping nicely for like 5 minutes.
I shut the car off and when i went out like 3 hours later it was weak and the voltage drops got real bad.
Now i have it loaded to 4 ohms so 300rms and now its dimming still....almost as bad as it was at 1 ohm,noticeable clipping too.
Could i have messed up my amp? Im still leaning towards a bad alternator cause even when i put the blinker on my dash lights dim now.
I will take it to the shop and have the amperage checked in the next couple days.
druidpagen 
Member - Posts: 13
Member spacespace
Joined: November 09, 2006
Location: United States
Posted: November 09, 2006 at 10:25 PM / IP Logged  

actually you weren't drawing as much amps as you thought. i did some calcs and you were running about 105 amps and probaly peaking slightly over that. wich is your problem.,your alternator was constantly recharging your your bat. runnning 4 ohms (300 watts) is like burning $ and a wast! eather way your gonna have to spend some cash to get up to optimal performance. earlier posts had some good sugestions.

*add another alternater (or stronger one), battery or both. wich would probably be the more expensive aproach but will let you run your 1200 watt set-up.

*sell your subs and get  2- 4ohm subs wired to a 2 ohm load and run 600 watts wich would draw around 66-75 amps giving you some head room. this would probably be cheaper than option 1.

unfortunetly your hot load probably ruined your alternator (wich im almost positive) being an installer and mechanic. which is probably the problem right now.  your battery is probably ok unless you ran your first set-up for a long time or ran it dead. if you ran it dead pitch it. autozone can check your battery for free so atleast that's one cheap thing. good luck 

wirewise 
Moderator - Posts: 489
Moderator spaceThis member has made a donation to the12volt.com. Click here for more info.spaceThis member consistently provides reliable informationspace
Joined: March 07, 2002
Location: California, United States
Posted: November 10, 2006 at 10:07 AM / IP Logged  
sedate wrote:
wirewise wrote:
Feel free to argue all you like, but it will not change this fact.
I take your leave to argue. Sometimes I get scared on this board.
wirewise wrote:
Adding more or larger batteries is really only a band-aid for the additional load placed on the existing electrical system once it has exceeded the output of the alternator. Yes, it will appear to solve the problem at first, but eventually the system will fail.
Okay. I think I figured this guys current draw to be like.. factoring amp overhead, a solid 150amps. At a 105amp alt, i dunno, 25-50% of which goes to the vehicle proper..this does leave a rather enormous power deficit. Of course.. this rests on the obviously incorrect assumption that power draw will *always* be 150amps + what the vehicle needs. A *constant* pull of 200+ amps would of course overwhelm a stock alt backed by *any* amalgamation of batteries in short order. This is however, is not typical behavior of a monoblock amplifier. The nature of dynamic music would only require such output.. every.. I dunno.. sayy.. 1/2 of a second, every other second. So 75% of the time the alternator is *well* above what the system requires for optimum output.
SOOOO ... utilizing larger batteries... which, on the whole, net more or less what they release, and are less susceptible to interminent voltage drop-off than the stock SLI batteries, is a highly competetive solution to the original posters' problem.
A 105 amp alternator, or any other for that matter, does not continuously put out a 105 amps of current. Alternators only put out as much as is demanded from them up to their respective rating. Averages mean nothing with regards to the maximum load placed on an alternator. Once the maximum load exceeds the output rating of the alternator, any one of the three sets of rectifying diodes are in danger of being destroyed. For each one of these that fails, maximum output is reduced by a third. And yes, adding more batteries will put an additional load on the alternator.
BTW, there's nothing to be scared of on this board, unless of course you fear learning something new ;)
~wirewise~
astro88 
Copper - Posts: 195
Copper spacespace
Joined: December 01, 2003
Location: Canada
Posted: November 10, 2006 at 1:11 PM / IP Logged  
Went to the alternater shop today and got the system checked and its working like it should?
Can anyone reccommend a good place to order a ho alternater   
that will ship into canada,or preferably one that IS in canada?
kicker guy 
Copper - Posts: 86
Copper spacespace
Joined: August 25, 2006
Location: United States
Posted: November 10, 2006 at 1:22 PM / IP Logged  
Generally I don't like to recommend ebay but i like Iraggi alts
sedate 
Silver - Posts: 1,173
Silver spacespace
Joined: July 03, 2004
Location: Colorado, United States
Posted: November 11, 2006 at 1:02 AM / IP Logged  
wirewise wrote:
And yes, adding more batteries will put an additional load on the alternator.
See... even if.. somehow.. this is true.. which.. I suppose it would be in .. in a way.. I'm just not sure I understand why it would even matter in this application. The idea is "Get my amps to work" ... adding huge power capacity will accomplish this.. and do no harm to the batteries or the electrical system..
Would you agree that adding paralleled deep cycles by themselves isn't going to cause catastrophy to the car? Would you agree that all other things being the same, doing that would have absolutely no effect on vehicle operation what-so-ever?
Soo.. if you had a deep cycle.. in my scenario, the ubiquitous Yellow Top.. that can put out like 25 amps for a solid hour before it drops under 12v.. and then have two of them.. right? Then attach a power supply that at most would supply like half of all the power that that car could possibly need.. an operating alternator.
So attached to this you are asking intermitent 150 amp pulls and this is going to somehow fry out batteries with that sheer amount of storage?! Nevermind batteries that can physically withstand the huge power drains that are actually being asked of it?
wirewise wrote:
Once the maximum load exceeds the output rating of the alternator, any one of the three sets of rectifying diodes are in danger of being destroyed. For each one of these that fails, maximum output is reduced by a third.
This is absolutely correct. So.. wouldn't it be desirable to keep huge loads *away* from the alternator and on Deep Cycle batteries that are made for such abuse? Electrical generators off all kinds like thier loads constant.. so wouldn't having a real battery between the alt and the amps be desirable.. regardless of alternator output?
Which brings us back to the original poster.
astro88 wrote:
Now i have it loaded to 4 ohms so 300rms and now its dimming still....almost as bad as it was at 1 ohm,noticeable clipping too.
Could i have messed up my amp? Im still leaning towards a bad alternator cause even when i put the blinker on my dash lights dim now.
Yea you killed your battery. You (sort of) indicate that you had your electrical system checked, but you might want to remove the battery and do that one on its own. See.. what happens to SLI batteries when you ask that kind of power outlay is very similer to what you describe here.. blinker causing light dimming and such. While the battery reads 12v at the poles and can sort of start the car.... any actual load beyond the 20 or 30 or so amps it takes to start the car brings total failure to the electrical system as it instantly brings the system down to unmanagable single-digit voltages from the warped, corrupt battery. A properly functioning alternator, which you won't have for long if you don't LAY OFF THE AMPLIFIERS UNTIL YOU GET SOME REAL BATTERIES, will *NOT* always properly power a vehicle when the battery is corrupt..
Again.. the battery was DESIGNED to start the car and then run on the alternator. (I guess I'll concede that) But you asked it to run ENORMOUS amplifiers and you need a battery(ies) that can stand up to that sort of abuse... REGARDLESS of alternator output... particularly with amplifiers of this size.
"I'm finished!" - Daniel Plainview
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