power problems
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=42216
Printed Date: April 28, 2024 at 6:43 AM
Topic: power problems
Posted By: wheelerdr
Subject: power problems
Date Posted: November 04, 2004 at 1:10 AM
I have a1995 chevy with 2 yellow top deepcycle batteries, runs the whol system. I purchased a 140 amp alt. from local part store, and a 1 farad cap. I have the 2 guage power wire running on a 100 amp fuse to the cap and then to the my Kenwood 811d(heard it was a power hog) and a 2 guage ground from the amp to the frame, a 2 guage ground from the cap to the same spot as the amp. I have put a 2 guage power wire from the alt-to the battery. a 2 guage ground from the battery to the fram and from the alt to the same spot as the battery ground. I have a rockford punch stage 3 in a ported box, wired 2ohm + 2ohm, itis at 4ohm now only driving 500 watts from my amp, but when low bas hits my voltage still drops low, and distorts, gain is set to about half, set to 60 htz. bass on radio is set to 0. can anyone tell me what my probleme is. I was thinking about buying a 200 amp high output alt, or adding my old 105 anp alt to my truck, but do not know how to wire the second alt. was told I would need an isolator but where to get one. and how to wire the black plug into the second alt, my black plug is on the first one. any help would be outstanding. thanks SSgt Wheeler USAF Alaska
Replies:
Posted By: kfr01
Date Posted: November 04, 2004 at 1:32 AM
Don't upgrade your alt. again. Something is wrong. That amp is only rated at 75amps and I find it hard to believe it is pulling anywhere near that much during your daily driving, especially with a ported box. Anyway, hopefully someone else with more power system experience will weigh in, but I highly doubt that you need more amperage.
In the meantime, I would check your gain. If your amplifier is driven to hard clipping it can try to pull much more power than it should. This would cause just about all the problems you point out.
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New Project: 2003 Pathfinder
Posted By: wheelerdr
Date Posted: November 04, 2004 at 1:46 AM
Yea I will check my gain I know it is only hlaf way up. I hope others will help to i see alot of views but no post, thanks alot
Posted By: supradude
Date Posted: November 04, 2004 at 7:34 PM
Did you charge the cap before you hooked it up? Or are you sure the cap is good? I was having a problem similar to yours, and found my cap had gone bad. You don't need a bigger alternator, or 2 of them with the power you have. Make sure of all your connections are secure and grounds are to bare metal.
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'85 Toy
Posted By: forbidden
Date Posted: November 04, 2004 at 8:01 PM
Measure the resistance on the ground return. Connect 1 end of your dmm to the - battery terminal. Disconnect the ground wire from the amp and connect the other probe to the end of this wire. Do not touch the wire and make sure that the wire does not contact anything else. A good ground will show under 1/2 ohm of resistance. GM vehicles are notorious for having a poor ground return. Post up your results.
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Top Secret, I can tell you but then my wife will kill me.
Posted By: wheelerdr
Date Posted: November 04, 2004 at 11:06 PM
I have checked my gain and it sems to be good only half way up and set to 60 hertz for bass, I have checked that all my grounds are on bare metal and very clean, forbidden what is the best way to check the ground return. with my battery in the front of the truck and my amp in the back of my extended cab with a 10" long wire. any sugestions. or am I just not getting the picture. thanks
Posted By: stevdart
Date Posted: November 04, 2004 at 11:40 PM
Rob might be busy so I'll put my thoughts in on this. You have to run a length of wire from the battery negative back to the amp, copper wire and the larger the better. The wire has resistance, so it has to be measured first. Also, the DMM has internal resistance and that, too, has to be deducted. Find the internal resistance by touching probes and getting a reading. My DMM, for example, reads 0.8 ohm internally, so I deduct that from any reading. Get your reading of the farthest end of the ground wire from the chassis / wire to battery.....then deduct the total that you came up with previously. A good ground will be 1/2 ohm or less. This order: measure DMM internal resistance. That's value no. 1 Measure resistance of temp. wire, then deduct value no. 1 from that. that's value no. 2 Connect temp. wire to battery neg. and disconnect ground wire from amp. Measure from ground wire to temp. wire, then deduct the two values. ------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: chevyman26
Date Posted: November 05, 2004 at 12:15 AM
wheelerdr wrote:
I have checked my gain and it sems to be good only half way up
The position of the gain potentiometer really doesn't matter at all, either. As long as you're using a DMM to check the ground, go to this link - https://www.jlaudio.com/tutorials/index.html and click on the Gain setting tutorial. I used to think I had my gain for my sub set pretty close, then I learned the right way to do it. Now, set correctly, my gain is just barely over 1/4 of the way up. The actual position will depend on the voltage from the preouts on your headunit. Nothin' beats a properly set gain. As far as the alternator goes, I'm still running the stock 105 amp with a basic Interstate 800cca (i think) Batt., with no cap., pushing around 400 clean watts, and I get slight dimming only at idle, with no other problems (in a '97 Chev. ext. cab), so your 140 amp alt. should be plenty for your 500 watts. ------------- You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."
Posted By: haemphyst
Date Posted: November 05, 2004 at 12:39 AM
Check the output voltage of the alternator (from alternator output post to alternator chassis), with the engine running, and slightly above an idle. Check the voltage at the front battery, again, engine running. Check the voltage of the back battery, then the cap, then right on the amp power terminals. At each of these points, with your DMM connected, try to duplicate the issue. Wherever you start to see a voltage drop, this is where you need to start looking to address the issue - ONE CONNECTION STEP AHEAD OF WHERE YOU MEASURE THE VOLTAGE DROP. Example: If you measure correct voltage at the cap, but not at the amp, the issue is in the wiring or connections BETWEEN the amp and the cap. Easy... If the issue cannot be resolved with all of your electrics connected, start to remove each electrical component, one at a time, (while leaving the circuit complete to power the amplifier, of course) and then follow the same steps outlined above... It's a lot of work, but you will get there. My guess is, your alternator or regulator is bad or going that way. I know you said it is new, but anything can happen with electronic equipment.
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: chevyman26
Date Posted: November 05, 2004 at 12:56 AM
wheelerdr wrote:
I have a rockford punch stage 3 in a ported box, wired 2ohm + 2ohm, itis at 4ohm now only driving 500 watts from my amp,
Just want some clarification here - you do mean wired in series, right? If it is wired in parallel, you'd be putting a 1 ohm load on the amp. If so, it would probably go into protection mode, but you never know. ------------- You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."
Posted By: wheelerdr
Date Posted: November 05, 2004 at 9:59 AM
yea it is in seriies now, I wanted to go to 1 ohm so I could drive this sub at around 900 watts but If I cannot get imy electrical system to handle the 500, then the 1000 is out of the question. Thanks for all the advice I am going to go to work on my truck will post the results asap. thanks
Posted By: SmokeyJMB
Date Posted: November 05, 2004 at 12:38 PM
Did you hook up a battery isolator? if not you need to. Stinger makes a nice one that is not to expensive. What the isolator will do is let on battery run the car and the other one run the system but the alternator will charge both.
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DO it right, Don't use SONY
Posted By: haemphyst
Date Posted: November 05, 2004 at 12:59 PM
DO NOT INSTALL AN ISOLATOR! Read this recent thread regarding the subject. There are also many others regarding the very same subject on this board, but this is the most recent. ------------- It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: wheelerdr
Date Posted: November 05, 2004 at 2:05 PM
ok i will read it, but I think everyone mught think I have one battery for my truck and another one for my AMp but My truck runs off of 2 batteries. It is a diesel with 2 batteries
Posted By: forbidden
Date Posted: November 05, 2004 at 2:24 PM
I was going to guess this small fact but did not have a chance to. Any luck with that resistance reading yet?
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Top Secret, I can tell you but then my wife will kill me.
Posted By: wheelerdr
Date Posted: November 05, 2004 at 3:03 PM
no im in a air force class all day just comming home for lunch, does anyone no wher i can download a test tone so i can set my gains
Posted By: wheelerdr
Date Posted: November 05, 2004 at 8:13 PM
I down loaded a test tone (I think) put my desk at about 3/4 with bass and trebel at 0, disconnected the sub, and conected my multimeter on the = and - for the sub output of the amp and I could turn up the amp all the way and did not get any volt reading from it. I looked at the jl audio tutorials and I should have gotten at least 47.3. Am I doing something wrong
Posted By: stevdart
Date Posted: November 05, 2004 at 8:30 PM
Set your DMM for AC volts. And we will need to know about that ground resistance, too.
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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
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