Lights dimming WTF?

[altoncustomtech 10+ year member]

Hey guys, I've just got my van back from the mechanic (head gaskets). While there the system was out but I left the stupid CAP in and it got stolen. I've had it back for a couple of weeks now and I've had a few problems with it. 1) The Exide Orbital battery died, no one knows why but I replaced it with the second one I got for my car (upcoming build log) and it was DOA and never used so I've installed a Red Top. So the starting battery problem has been fixed. 2) Severe noise similar to white noise, turned out the little fuse in the Pioneer HU was blown, neatly soldered a wire into place and that problem is fixed. Now it was at the mechanics about 4 months (since late August '08) and I've been diagnosing these other problems for a few weeks so we've been easy on the system, no bumpin' too hard until here lately. I'll be dammed if now I've got a voltage drop issue and the lights are dimming. To fill in the background here this thing has a 250A alternator, BIG 3 is done, terminals and connections are clean as can be after changing the battery out twice. It only has one BXi2006D subwoofer amp running two BX12D2 Brutus subs wired series-parallel for a 2 ohm load at the amp. The voltage is dropping from 14.8 at idle to 11.5 on a bass heavy hit such as the ones found in Lil Wayne's A Milli. So anyone have any ideas on where I'm going wrong here. I should have a little more stability than that seeing as I'm only running 1900 Watts RMS total (when you add the Zeus 6006 running 2 ohms stereo) and thats more than likely an optimistic number. Any suggestions here would be greatly appreciated guys. --Also the alternator has been tested giving 260 amps of output at 2800 RPM and 112 amps at idle.

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[chase007 10+ year member]

Check ur wires maybe the alt to the batt isn't giving it a good charge...I'd get out the voltage meter and check every wire in the big 3.

 

[jeres313 10+ year member]

put an extra battery in there... that should do the trick...

 

[jdawg 5,000+ posts]

I would say first upgrade all your stock chatging wires (big 3) then add another batt

 

[Enellz 10+ year member]

Before you ANYTHING AT ALL, check your voltage with a DMM everywhere

 

[altoncustomtech 10+ year member]

I would say first upgrade all your stock chatging wires (big 3) then add another batt

BIG 3 is already been done...... 2 Guage wire ALT to BATT + , BATT - to chassis, ALT mounting bolt (engine) to chassis and even a 4th ALT mounting bolt to BATT -

The BIG 3 is covered

 

[altoncustomtech 10+ year member]

Before you ANYTHING AT ALL, check your voltage with a DMM everywhere

I've checked the voltages at the battery and amps the carry the same voltage with both the system at idle and at full tilt.....

 

[loopkiller 10+ year member]

Your battery died because it was sitting for 4 months without being charged. I would not expect a single Redtop under the hood to power 1900W RMS of music anyways.

Oh, and BTW, the guys at the shop tossed the cap in the trash for you, where it belongs. //content.invisioncic.com/y282845/emoticons/fyi.gif.9f1f679348da7204ce960cfc74bca8e0.gif

 

[n2audio 5,000+ posts]

put an extra battery in there... that should do the trick...

I would say first upgrade all your stock chatging wires (big 3) then add another batt

I would not expect a single Redtop under the hood to power 1900W RMS of music anyways.

Why all the concerns with the battery?

As long as the car is turning over the battery shouldn't even be a factor. The 250A alt should power a 2Kw HF class D w/o the battery ever being part of the equation.

I wonder if the Volt Reg in the alt isn't working the way it's supposed to be, just taking some time (a fraction of a second would show up as dimming) to up the current, but the ~11v measurement doesn't make any sense.

 

[loopkiller 10+ year member]

As long as the car is turning over the battery shouldn't even be a factor. The 250A alt should power a 2008d w/o the battery ever being part of the equation.
I wonder if the Volt Reg in the alt isn't working the way it's supposed to be, just taking some time (a fraction of a second would show up as dimming) to up the current, but the ~11v measurement doesn't make any sense.

It makes every bit of sense. His alt cannot keep up with playing music. I have no doubt it would be fine if he was burping though. Since his alt cannot keep up with the dynamic load that music presents, it is depending on his battery for the additional power. Since it is only a Redtop way up under the hood, he is seeing big voltage drops. This is to be expected with his setup.

OP I think that if you play a test tone instead, you will see your voltage stay much closer to your charge rate than if you were playing music. Give that a try and see what happens. Post back so we can see.

 

[n2audio 5,000+ posts]

I still disagree. A 2006d at 2 ohms is going to draw - AT MOST - 123A, and that would happen very rarely, if ever. Why should an alt measured 260A at 2800rpm and well over 100A at idle struggle with that when you know as well as I that systems of similar power have been known to run fine on 1/2 the charging system?

You CERTAINLY don't need a 2nd battery, but make sure the one you have is healthy. To have drops to

 

[quins90lac 10+ year member]

BIG 3 is already been done...... 2 Guage wire ALT to BATT + , BATT - to chassis, ALT mounting bolt (engine) to chassis and even a 4th ALT mounting bolt to BATT -
The BIG 3 is covered

ok so let me get this you have a 250w h/o alt and you did the big 3 in 2 awg ? i think the 2 awg on the big 3 might be your problem unless you mean 0/2 awg cause i heard you have upgrade to at the least 0 or 0/1 awg if you upgrade your alt . and just out of curiosity what size fuse is your alt to bat wire fused with

 

[microhaxo 10+ year member]

The 2gauge wire is fine for big 3, at 2 ohms he isnt pulling much past 1200w rms.

The length of that 2 gauge is less than 3 feet it should easily be able to handle 100a loads and I SERIOUSLY doubt he is even pulling 80a loads.

I would have your battery tested under load at autozone or pepboys just in case.

Otherwise it might be your ALT, Check all cables connected to the alternator and re connect them. When my car was worked on they pulled out the plastic clip and when they put it back on they broke a small part of it on the inside so it wasnt very secure. Anyway long story short my alt would randomly not charge my battery from a bump or vibration.

 

[quins90lac 10+ year member]

no 2 awg is not fine for a big 3 when dealing with a 250 amp alt . what im saying is with a 250 w amp using 2 awg is simply not except able . ask mechman if you should use 2 awg for a 250w alt .seeing how electricity will take the path of least resistance with 2awg your creating more resistance then their needs to be .if he weer to up grade his big 3 to 0 or 2/0 or even welding cable his dimming issues will probity go away cause maximum amps for power transmission is only 94 amps while 0 is 150 you do the math cause i did and that's 56 amps of power hes losing . if he goes to 2/0 then he picks up like 96 amps of power and with the 250amp alt figured in it goes like this for his loss 2 awg loses 156 amps 0 awg loses 100 and 2/0 he only loses 60 amps . now if it weer me ide want to lose as less as possible . that and its winter the battery is cold and he probably running the blower motor

 

[altoncustomtech 10+ year member]

Thanks guys for the input, it is regular 2AWG wire and I'll be picking up some 0/1 or even 0/2 if they have it in stock. I figured with the short runs (longest is 18") that the 2AWG would be ok for this application. I believe the voltage regulator is working just fine, however the alternator was tested at those levels before the Orbitals went to crap so there's a chance I may need to retest it off the engine. I've had it tested with Advance's portable tester and it passed with flying colors tho. Just when I thought I'd already spent enough money. //content.invisioncic.com/y282845/emoticons/laugh.gif.48439b2acf2cfca21620f01e7f77d1e4.gif Not with this hobby.