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severe voltage drop, bad alternator?


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astro88 
Copper - Posts: 195
Copper spacespace
Joined: December 01, 2003
Location: Canada
Posted: November 08, 2006 at 12:58 PM / IP Logged  
The car is a 92 z34 stock alternater(105 amp)
The system is kicker kx1200 running two re se 10s.
zapco ag200 running components
Alpine 9815 h/u
All 4 awg wiring to amps and grounds.
Ive upgraded the grounds ,battery to bdy, battery to engine,i havent done the alt to battery(those that know the z34 know why).
When i have the system running moderately the lights dim very badly,if i push it really hard the car will actually stall!
with system off im reading 13.8-14.3 at the amp,when i push it hard the voltage drops down to low 11s when the bass hits.
I had a 1 farad lightning audio cap in there(which i removed today to see if it was helping or hurting)and its worse now than b4.
I know 4 awg is pushing it for a kx 12oo but i had one in another gm 2 years back ,all 4 awg as well with no issues at all.
Any input is welcomed thanx.
forbidden 
Platinum - Posts: 5,352
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.spacespace
Joined: November 01, 2003
Location: Alberta, Canada
Posted: November 08, 2006 at 1:44 PM / IP Logged  
Bad alternator, bad battery quite possibly as well, bad ground (read the grounding sticky) and you should be using a 2 or 0 gauge wire ideally. Meter the voltage at the alternator, what does it show?
Top Secret, I can tell you but then my wife will kill me.
Alpine Guy 
Platinum - Posts: 2,478
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Joined: October 18, 2003
Location: Canada
Posted: November 08, 2006 at 1:58 PM / IP Logged  
I would have to say old alternator being hit with an impossible task.  Even if the alternator was brand spanking new, you would have the same problem, you need to upgrade that alternator. You need at least a 150 amp alternator, 180 amp would be perfect and anything better is, well, better.
2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.
astro88 
Copper - Posts: 195
Copper spacespace
Joined: December 01, 2003
Location: Canada
Posted: November 08, 2006 at 2:13 PM / IP Logged  
forbidden wrote:
Bad alternator, bad battery quite possibly as well, bad ground (read the grounding sticky) and you should be using a 2 or 0 gauge wire ideally. Meter the voltage at the alternator, what does it show?
I checked the voltage drop at the battery as well as at the amp,it read pretty much the same.
As for checking at alternater.....on the z34 the alternater is mounted low on the 3.4l engine which makes it near impossible to get to.
i did try to put a new wire on it from the wheel well area but i ran out of patience(and bandaids!)
I know 105 amps is pretty lacking for this amp,but im really not pushing it that hard and the dimming and stalling just really seems excessive.
The alternater in like 1.5 years old the battery is about 1 year old.
My grounds are all clean and scrapped of paint,ive tried different ground locations in the trunk,all with the same outcome.
I want to rule out any connection/ground issues before i look into buying a new alternater.
would a upgrade of the alternater wire to battery make a huge difference or should i just upgrade the alternater and wire at the same time?
I just dont wanna take the alternar out to change the wire and not fix the problem,its like a 8 hour job to change them is these cars!
Thanx for the input so far
Mad Scientists 
Silver - Posts: 380
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Joined: February 07, 2004
Location: United States
Posted: November 08, 2006 at 2:21 PM / IP Logged  

Have the alternator output checked.. not just voltage, but amp output also. Also measure AC voltage at the battery.. see if there's any. What it sounds like to me is either a weak alternator or you're pulling more amps then you think.

Jim

astro88 
Copper - Posts: 195
Copper spacespace
Joined: December 01, 2003
Location: Canada
Posted: November 08, 2006 at 3:22 PM / IP Logged  
Mad Scientists wrote:

Have the alternator output checked.. not just voltage, but amp output also. Also measure AC voltage at the battery.. see if there's any. What it sounds like to me is either a weak alternator or you're pulling more amps then you think.

Jim

I will check the ac voltage at battery, and how do i check output amps? withh dmm or do i need to take it to a garage?
More amps thani think? are you saying possibly a amplifier problem?
My gain on my amp is at about 10-11 o'clock sub out is set to +15 as im told to set it to (alpine 9815)
astro88 
Copper - Posts: 195
Copper spacespace
Joined: December 01, 2003
Location: Canada
Posted: November 08, 2006 at 3:47 PM / IP Logged  
Ok on my dmm i have it set to acv at 200,is this correct setting for ac voltage?
Anyways its reading 30.8 with engine running when i turn up the system it dips to 27.5-28.2
at the same time the 12v voltage dips from 14 to low 12s
with engine off the gattery ir reading near 13v and the ac voltage is sitting at 28.0.
the dmm i have is called equus model #4320 if it matters?
Mad Scientists 
Silver - Posts: 380
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Joined: February 07, 2004
Location: United States
Posted: November 08, 2006 at 5:38 PM / IP Logged  

I'm trying to help you determine if the alternator is outputting its rated output and you're drawing more than that, or if the alternator is weak and not outputting its rated output.

The AC measurement is to check for a shorted diode in the alternator..

The current output of the alternator needs to be checked with a clamp on ammeter.. if you don't have one, you'd need to either go to a shop, or find a friend with out.

Jim

sedate 
Silver - Posts: 1,173
Silver spacespace
Joined: July 03, 2004
Location: Colorado, United States
Posted: November 08, 2006 at 5:50 PM / IP Logged  
Huh.
Okay there isn't anything wire is going to do for your at this point. You have two *enormous* amplifiers and a 14 year old charging system.. that.. if you stop with this torture now.. you should be able to preserve in working order. But, seriously, lay off the stereo until you have another battery in your car or you might just fry out the alternator you have. (I destroyed a stock AC Delco alt in 3 days by adding a JL monoblock to my old car.)
I'm not really with the "bigger alternator or nothing"-crowd that usually frequents this forum. I would first try a true Deep Cycle battery, and see if that doesn't put enough of a buffer between your amps and your car.
*My* method of solving your problem would be to take *two* Optima Yellows and wire them directly together.. but you kinda have to buy them at the same time... there are some hardware issues here as well as far as termination rings and blocks and such.. (and a relay if you want to get fancy and disconnect the batts when the car is off) but for about $400 (well less than a new, higher capacity alt) you could wire them together, in parallel, with one in your engine and the other in your trunk. You get a much bigger reserve for your amps, and, by moving a battery right next to the amps and another one right next to your headlights, you'll find headlight dimming should be all squared away.
And you need to bite the bullet and run a wire from your + post to your battery. But don't even bother without some real power capacity between your car and your amps.
As far as another alternator goes.. that is probably the best bet in the end, but you would still get excellent results adding a new, preferably deep cycle battery in the car to support amps that ridiculously massive. I mean really dude. That is like... what? 1600 watts RMS?
Anyway, if you are going to go with an alternator, to make those worthwhile, in my experience, really requires some quality and money put into them.. by a Stinger or something of that nature.. I've had several alts rewound and have never had a satisfactory one... always like 9v output at idle and crap like that. Stick with big, expensive name brands for an investment like that.
I'd do the batteries.
   
"I'm finished!" - Daniel Plainview
sedate 
Silver - Posts: 1,173
Silver spacespace
Joined: July 03, 2004
Location: Colorado, United States
Posted: November 08, 2006 at 5:58 PM / IP Logged  
Mad Scientists wrote:
I'm trying to help you determine if the alternator is outputting its rated output and you're drawing more than that, or if the alternator is weak and not outputting its rated output.
What?! Of course he's drawing more than that. For gawd sakes he's got like two enormous amps in that little car. Isn't a z34 like a Cavalier or something?!
That Kicker amp alone should bury his alt nevermind the Zapco. He'd need all 105 amps just to meet that 1200watts of output.. nevermind another 10-30% in amp overhead. THEN add ANOTHER amplifier.. Zapco's are really beefy amps.. so he's probably, when he's pushing it, asking like 150 - 180amps off a battery that he has not indicated that he has upgraded at all.
Oh boy. All the caps and wires and multimeter prodding in the world are not going to help here. See above.
"I'm finished!" - Daniel Plainview
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