Thread: Lights dim when bass hits, weird.

Originally Posted by pancit175

The battery, while the engine is running, it is acting as an efficient capacitor. I wish I had the chance to get a picture or draw out what i'm talking about but I'll try to explain.
Long and short of it, you may already know this, but within the altenator, before it runs through the diodes, it is an AC voltage generator. And in simplest terms the negative portion of the AC voltage is reversed into a positive voltage. But because of this, the voltage is "dirty" with peaks and dips in the signal (kind of like: ^^^^^) And you may know that a capacitor is used to clean up this signal as a capacitor is resistant to change in voltage.

Yes, I know how an alternator works. The diodes rectify the signal so it is a bunch of "humps", otherwise the net voltage would be zero. Thanks for the clarification, but I still don't believe the battery regulates the voltage. It may "clean" the voltage, but one's voltage is usually much greater while the engine is running than while not. On my car, for instance, the voltage is around 12VDC while not running, but while running, the voltage is around 13.5VDC.

Regardless, I'm still sticking to my original advice: I think he needs a beefier alternator.

The voltage regulator handles voltage regulating. Through the 70's they were external, the 80's they were beginning to place them internally inside the alt. At one time you used to be able to adjust the air gap in them and raise or lower the voltage output. They then went solid state then internal. They are for the most part not replacable as you just replace the entire unit. There have been rumors for years now that at a near future the power demands will surpass the 12 volt system and manufacturers will move to 24 volt like they did with the change from 6 volt.

Having any luck? First, the battery doesn't clean the voltage bro. The battery and alternator are connected in a 'Parallel' circuit, not 'Series', which is why you can disconnect the battery on a running car and it will continue to run. That being the case, the current will follow the path of least resistance to it's destination and take a direct route, not go through the battery. The battery only comes into play on a running car when the alternator voltage drops below the battery voltage.

Second, Keep in mind the when checking Ohm's on a speaker, it's going to read less. For example, a 4 Ohm speaker might read 3.2 Ohm's or so with a digital multimeter, so be aware of that and don't go tossing speakers because they're less than you expect. This is because the speaker is rated in IMPEDANCE, which is rated against AC current. Impedence is a combination of Resistance, Capacitance, and Inductance induced by AC current, whereas a Multimeter uses only DC power and takes only the resistance into account. Does that make sense?

Anyway, now that that's clear....

It looks like you're using your deck to power you speakers. You swapped it out with a different deck, same result. This will only happen when the current draw is too much for the charging system to handle, and there's only a limited number of things it could be.

First, Disconnect the carputer and throw a CD or something in the deck. If it stops, it's the carputer.

Second, if you have the RCA's to your sub amp unhooked that should be fine, but disconnect the Remote turn-on cable just to be certain.

Second, run an extension cord out and power your PC with house power to see if it's the power system. Is it power directly by DC or an inverter?

Third, if you don't think it's the carputer, turn the fade all the way to the front or rear so you're only powering 2 speakers, see if that helps (won't mean alot, but good to get as much info as possible on the symptoms)

If you do think it's something with the carputer, try running a different audio input into your deck, like an iPod, or from a home amplifier with an extension cord. If this solves the problem, it's definitely the carputer.

Basically you want to pull each component out of the system 1 at a time until the problem is solved. Gotta narrow it down to some portion of the system. Something is pulling way too much current, or you alternator is crapping out. You said you had your battery checked, have the alternator checked as well.

You can leave your car not running, and use jumper cables to connect to a friends car and let his charging system power your car for testing. If the problem goes away, then it's most likely your alternator, since chances are he'll be putting out less current than your system should.

Also, Disconnect your speakers from the deck and use a multimeter between the 2 speaker wires and make sure nothing is shorted, meaning nothing should be 0 Ohms. In my experience, a speaker with 4 Ohms impedance with have around 3 Ohms resistance when measured with a multimeter.

That's about all I can think of. Another possibility is the amplifier in the Deck just isn't very efficient, but apparently this only started after the CarPuter install, so that shouldn't be the problem.

Any way, hope that all helps, and good luck.

Originally Posted by durwood

First he has already upgraded his alternator, second no way does he need a bigger alternator-just to run his headunit, come on now. If there is no signal going to his sub amp then it's not drawing ANY current other than to idle so maybe a amp or 2.

Secondly, the regulator on the alternator is too slow at times to deliver more current instantly, therefore the voltage starts to drop to the voltage level of the battery, which provides reserve current. SO a battery does regulate essentially.

Anyway, the op has done a pretty good job of trouble shooting IMO, but I would like him to answer the questions I asked earlier, before he goes and starts spending more money on what could be something really simple.

The regulator is not designed to deliver any more power than the 13.3 to 14.1 it is designed to do. Which does not matter anyway as the amps is what is needed here. If his car is pulling more amps than the alternator is pushing out regardless if he upgraded already, he needs a bigger alt. If he has multiple or high draw amp(s) his carputer, whatever other factory options, plus AC and anything else he added aftermarket he may well not had upgraded to a big enough alt. Besides if he went with a larger factory unit he probably only added 10 to 20 amps.

it is probably the alternator. if its an upgraded unit they sometimes provide less current at idle rpms than a stock unit. and only get to "high" output at higher rpms 4-5k
my 2 cents, now i'll slowly back away from this thread