Hollyw00d
I just installed a 200amp alternator on my 2005 jetta (old style), did the big 3 with some 1/0, and ran 1/0 power to the trunk. I have a new optima 34r red top. I'm running a 12" shocker super xtreme with an earthquake ph-d2. When I crank it up, the headlights dim real bad. On a steady tone, they stay dim, so I don't think it's the alternator reacting slow. They MAY brighten very slightly on a steady tone, but it's hardly noticeable, if anything at all. The dash will dim slightly also.

If I were to compare it to my old 95' beretta with the stock alt and 2 batteries, the dimming seems worse. This is all while driving. I have no idea what it could be.

I few idea's I have:
-bad ground at the amp (although I don't know why I'm even considering it :\ )
-car's computer limiting output.
-battery is bad. Doubtful because the car cranks over great, but, it was completely drained due to the old alternator going bad. Charged it with 12amps for about 30-60 mins, then 8amps the rest of the way.

But as I said, I really don't have a clue.

[ 07-05-2010, 01:00 AM: Message edited by: Hollyw00d ]
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D-Bass
quite likely that the alt is computer controlled.

what is the resting voltage of the battery with ignition OFF?

what is the IDLE voltage with the engine running, measured at the front battery?
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Hollyw00d
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Originally posted by D-Bass:
quite likely that the alt is computer controlled.

what is the resting voltage of the battery with ignition OFF?

what is the IDLE voltage with the engine running, measured at the front battery?
The first resting voltage I got was 12.28-12.35, and it was not directly on the battery posts, but on the terminals connected to them. I turned the car on and got a 14.42-14.45 at idle and 2krpm, directly on the posts. Then I measured again directly on the posts with the car off and got a 12.53ish.

Additionally, something came on when the car was running, sounded like a fan (but it wasn't the radiator fan.) I'm pretty sure it was some secondary air intake thing, came from towards the bottom of the engine. I've read about it before but forgot what it's called. Anyways, the voltage dropped to the low-mid 12's then back up to 14 while it was still on I believe. I'm going to get some reading with the sub playing.
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D-Bass
a redtop battery should rest around 12.9V after the higher float charge drains away.

An AGM battery that is resting at 12.25 is only 50% charged.
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Hollyw00d
hmmm, I charged it up to about 95% the day i installed the alternator
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Hollyw00d
Quote:
Originally posted by D-Bass:
a redtop battery should rest around 12.9V after the higher float charge drains away.

An AGM battery that is resting at 12.25 is only 50% charged.
I'm not sure about that now.

I disconnected the battery chassis ground and hooked up my charger with a 2amp charge and it's up to 14.8 volts (probably just what the charger is putting out) and 80% charge and rising quickly. With my charger, the battery% display climbs very quickly until it get's to the actual level of the battery, then the display slows down to actual charging speed. Maybe there is a slight, but abnormal draw when my car is off?

15.2v and 88% is what it steadied at.
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D-Bass
i don't think it matters much what its saying while it's on the charger, at least at this moment. Right after you turn off the charger, it should be reading 13+ volts. If you let it sit for 20 minutes with a meter reading it the whole time, you should see it drop to about 12.9V as the float charge bleeds off and the plates cool.
If you're battery isn't resting near 12.9V, it's either not charged, or there is something wrong with the battery.
If you don't believe me about a 12.2V battery only being about 50% charged, check with a company that manufacturers 12V AGM batteries and you will see.

not sure what kind of charger you are using, but I wouldn't trust the charge readout on most chargers.
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Hollyw00d
Quote:
Originally posted by D-Bass:
i don't think it matters much what its saying while it's on the charger, at least at this moment. Right after you turn off the charger, it should be reading 13+ volts. If you let it sit for 20 minutes with a meter reading it the whole time, you should see it drop to about 12.9V as the float charge bleeds off and the plates cool.
If you're battery isn't resting near 12.9V, it's either not charged, or there is something wrong with the battery.
If you don't believe me about a 12.2V battery only being about 50% charged, check with a company that manufacturers 12V AGM batteries and you will see.

not sure what kind of charger you are using, but I wouldn't trust the charge readout on most chargers.
It's a schumacher 1200a. I believe you about the 12.2v 50%. The charger says 99%. Is it possible that there's a drain which makes the voltage readout lower when the car is off? I'll try disconnecting the battery/reconnect and get some readings.
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Hollyw00d
It's already down to 12.7 and still dropping no more than 2 minutes off the charger. Optima's site says between 12.6-12.8v though. I'll see if it goes back down to 12.3
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D-Bass
you may try giving it a hot charge, then draining it back down to 11V, then hot charge to 14+v, then drain, then hot charge, repeat, etc. to try to bring the battery back to life. This could bring it back to life, or it could take the battery's "wounded cell" and put it out of its misery for good.
OR find someone with a powermaster/xs charger. I forget the model number, but I've heard stories of them bringing batteries back from the dead.
If you can't get the battery to rest at least at 12.7 a few days after being taken off the charger, you have a bad cell in the battery and need to replace it.

In my car I used to have 1Redtop, 2yellowtop G34's, and a 200A alt and a smaller pulley. This was running TWO Ph-D2's.
I replaced all 3 batts with one XS-Power D3100 in the back, and there is plenty of power to run those and another 1200rms for the mids/highs. I have now swapped the D2's for a single 3kW amp

My D3100 rests at 13.0-13.1V in typical conditions, and not lose a tenth of a volt with the domelight and radio memory on for 7hours. that test was in my mazda though. your vehicle being a 2004+ german vehicle, there is quite possibly a slightly higher drain for the first 45min-2hours before the computer shuts goes to sleep the last stage.
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Hollyw00d
It's at a steady 12.59-12.6 for about 2 hrs now. Other than the battery, what else might it be, if anything?
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Loudcav
perhaps the charger sucks alot of us prefer the XS Power Intelicharger its not cheap but if you have used it or seen it used you will understand why its worth it
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Hollyw00d
Ran some more tests today and last night. Last night with the system blasting with the car off, headlights on, I had slight to no dimming. Turned it on, it was dimming again.

Got home from work today, and the highest voltage at the terminals with the car running was 14.0v. With the headlights, fog lights, and a/c full blast I got about 12.5-12.6v. With the headlights off it was just over 13v. With the a/c off it was back up to 14v. With the car off it's between 12.5-12.6v. Very strange because I've seen 14.4v with the car running.
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Loudcav
well it is hot out
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Hollyw00d
Quote:
Originally posted by Loudcav:
well it is hot out
yeah i know, I'm just throwing everything out there though man.
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