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Old 05-17-2011, 08:59:33 AM   #1
RXL
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Lack of voltage?

I have a 76 and wondered if these alternators are up to the task of running amps or is it more likely my grounds.
The audio sounds ok when the engine isnt running and is ok for about 15 minutes running, then gets a static sound. No whining, but more like a bad radio signal. RCA's run down the opposite side of the car from the speaker wires.
Only one amp is hooked up right now. It's an alpine 4 channel 100watt rms x4.
2 guage runs to a distribution block and then 2 4 guage runs to the trunk. Block is at the firewall.
I posted this in electronics section a few days ago, but things seem pretty slow there. No replies.
Thanks for any ideas.
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Old 05-17-2011, 09:39:35 AM   #2
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One of my friends had a similar problem many years ago, here in europe...
Not in a camaro, ok....
It was a bad ground connection.
Try putting a wire from the ground of the amplifier to the negative of battery. If it works ok is the bad ground connection.
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Old 05-18-2011, 07:20:37 AM   #3
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Figured I had good ground, but maybe not. I'll have to find some time to mess around it more.
I dont listen to it much in a 4 gear car anyway, but when I hit the highway it would be nice.
Everything worked perfectly in the shop over the winter just hooked to a battery. As the battery got low, I got the same sound. Hook up th charger and it was right back to good sound.
There's a new battery in the car and it's taking a full charge, so ground is where I'll start. Cheaper than an alternator. lol

Thanks
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Old 05-18-2011, 07:27:45 AM   #4
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Quote:
Originally Posted by RXL
I have a 76 and wondered if these alternators are up to the task of running amps

The GM engineers designed your factory alternator to run the car's electrical needs.
Not the needs of additional large amp drawing stereo equipment.

If you're adding on stereo equipment you need to figure out how much more
juice you need your generator to pump out, to supply enough juice for your amps.

Sure it will work for awhile, but you're not charging the battery like you're supposed to be.
Then your battery will take a sh**. That's basically what's going to happen.....

My suggestion is to just get a CS130 140amp alternator if you're adding one amp.
If you're adding 2 or more, you'll probably need more then that. Louder it gets, the
more juice it sucks.
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Old 05-18-2011, 01:06:05 PM   #5
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I wont be listening to it often because I like to hear my car, but I have an Alpine m605-400rms x1 and a mrv345 4 channel-75rms x4.
I've installed many stereo's without any real tech knowledge but this is starting to annoy me. Everything is fine while the vehicle isnt running. 15 minutes into running and it goes for a crap. I swapped the grounds and still have the same issue.
Is there a junk yard upgrade I can grab for an alternator? Bolt in?
I have a 3 wire alternator and am looking for a cheap fix as I have other priorities for the car. It's new to me.

Also, can I run a 0 guage wire straight to the alternator from power on the battery? Leaving th power to the starter obviously. Will it aid in charging the battery? I did what is referred to as the "big three" on my 93 chevy truck and wondered if there is a simular upgrade for the Camaro
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Old 05-18-2011, 01:40:44 PM   #6
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yeah a third gen 105 amp alt is a bolt in, from a pre-serpentine belt car (pre 1988 I think). you just swap out the multi rib pulley for your v belt pulley and wire it accordingly for a CS series upgrade
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Old 05-18-2011, 04:31:22 PM   #7
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Got it, thanks.
Full size trucks have them too?
I'm sure they would. I'll know when I hit the bone yard. Need some A pillar trim too, so it's an excuse to go for a stroll.

Appreciate the input fellas.
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Old 05-18-2011, 07:36:58 PM   #8
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Quote:
Originally Posted by RXL
Got it, thanks.
Full size trucks have them too?

Yes. I think the newer GM trucks use CS-144's though, and they are big
AMP Generators. The LY6 one I got is 160amp from the factory.

I think someone else told me they go up to 200amp, but not sure if that's true
or what models to find them on.
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Old 05-18-2011, 07:54:06 PM   #9
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Do you happen to know off the top of your head if it's the same wiring configuration for these big amp alternators?
I can build a motor, but I cant wire a set of tail lights. lol
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Old 05-18-2011, 08:23:10 PM   #10
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It's just 2-3 wires on a modern alternator.

Frankly IMO it's the best way to break the ice for a wiring newbie.
It's so simple that when you're done it will give you more confidence.

Just get the biggest you can that matches your pulley setup and mounts correctly.
Then come here and ask about the pigtail wiring, and we can help.

Ricardo just posted a pigtail site that I rehosted in the High Tech Retrofits sticky.
http://www.qualitypowerauto.com/catalog.php?item=81
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Old 05-18-2011, 08:31:43 PM   #11
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Holy moly Ace, He doesnt need but around a 100 amp alt. He's not running 4 15" subs!!! lol Batt should last awhile with a 100 amp alt. The original is 60 amp I believe on my 73 no A/C. not sure if it was different with A/C. I ended up going 100amp when I bought the camaro.
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Old 05-18-2011, 08:40:43 PM   #12
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I'm not sure what the amperage was for the factory alternator.
70 something amps ??

I just factor in 2 amps for a stereo on average.
One amp for 4 speakers
One amp for a Subwoofer.

140 amps puts you in the clear with a little room for growth.
I'm putting my CB radio in my Camaro again. LOL

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Old 05-18-2011, 10:59:38 PM   #13
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lol, been awhile since I seen that movie. Classic

If I go the junk yard route, I'll make sure I get the connector and hard wire it to the existing harness.
Will the fuseable link have to upgraded or will it be ok?
Shyte...I'll have to look around the wire pile. I bought a 350 last year just because it was cheap and it was complete with alternator and starter. Parted it out, but I still have the harness somewhere.
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Old 05-20-2011, 03:46:03 AM   #14
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Here's a quick way to figure out what size alternator to run.

If you're running a 100 watt, 4 channel amp (25 watts at each channel) all you gotta do is divide the wattage by the amp's efficiency, then divide that by the voltage.

Since this is a 4 channel amp, it's probably a class A/B amp. Those run ~60% efficient.

100 watts ÷ 0.6 (<- 60% in decimal form) = 166 watts
166 watts ÷ 13.5 volts = 12.3 amperes

That's at full volume.

If it's an amp that puts out 100 watts at EACH channel (400 watt amp), then it'll require, basically, four times as much current.

400 watts ÷ .6 = 667
667 watts ÷ 13.5 = 49.4 amperes

Again, that's at full volume.

Without having fuel injection, with every option in the car on (headlights, rear window def., heater blower full blast, and the stereo at full tilt) I'd go out on a limb and say you might actually need a larger alternator than the stock 60 amp if that amp is a 100 watt x 4 channel amplifier.

If not, and it's only 25 watts x 4 channels, no worries. The stock 60 amp will be fine.
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Old 05-20-2011, 07:27:59 AM   #15
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It's 75 rms x4 at 4ohm and 150 x4 at 2 ohm load
The mono is 400rms x1 at 4ohm and 600rms x1 at 2ohm load.

Damn, I just polished and anodized this alternator. lol
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