jetta electrical help.

[soulnomad 10+ year member]

hey guys, im trying to figure out ways to stiffen my charging system, im having crazy voltage dips and am trying to figure out what size HO alternator/combination of batteries would work best, thanks in advance! =]

Stock Alternator:90A

Battery:Optima Yellowtop G34 (had 2 in parallel, too much of a strain on alty)

Wiring:All 0/1 (big 3, All grounds double checked secure)

Idle:13.5V max (dips all the way to 10.4V on long transients)

Resting:12.6V

Total Current Demand :273A (3700rms and 40% stock current demand)

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[KMS 10+ year member]

How many watts do you have to the subs?

 

[soulnomad 10+ year member]

conservatively 3700rms to front stage and substage.

 

[KMS 10+ year member]

conservatively 3700rms to front stage and substage.

I'm pretty new to caraudio and I think 3700rms on a 90amp alt is a lot. Anyway if you have a daytime running lights, get a euro switch to turn them off to get a little extra out of what you have or there is a wire to be cut. Just check vwvortex.

IDK if you drive a MK3 2.0 8v but if you do then you can get a 120amp alt from a VR6 MK3 for cheap. Check the vwvortex classifieds. 120amp alt still isn't going to be enough but it's better then the 90amp,

Many don't like Optima batteries and will tell you to get a kinect or whatever they're called. Many like those.

 

[soulnomad 10+ year member]

im an electrical engineering student and have been into car audio for a while and yeah its definitely overkill haha hence me asking for suggestions for alternator/battery configs.any other suggestions!?

 

[sexy 10+ year member]

hey guys, im trying to figure out ways to stiffen my charging system, im having crazy voltage dips and am trying to figure out what size HO alternator/combination of batteries would work best, thanks in advance! =]
Stock Alternator:90A

Battery:Optima Yellowtop G34 (had 2 in parallel, too much of a strain on alty)

Wiring:All 0/1 (big 3, All grounds double checked secure)

Idle:13.5V max (dips all the way to 10.4V on long transients)

Resting:12.6V

Total Current Demand :273A (3700rms and 40% stock current demand)

When you say total current demand is that the whole car or just the audio system? And I am an electrical engineer that competes in SPL so maybe I can help a little

Did you test with a dc amp clamp or are you coming up with those numbers some other way?

If your current demand is that high then you will have to have at least that much coming from the alternator or I might suggest alternators. I use three ho/alts to accomplish what I need and no I did not pay a lot of money for them.

 

[soulnomad 10+ year member]

yes i REcalculated total current demand accounting for amplifier inefficiency and actually looks like my amperage draw is 196.3A (the whole car with current one battery audio system).

 

[VWBobby 10+ year member]

The bare minimum would be a 220A alt (to have a margin of extra) and an upgraded battery.

I just traded in an 01 1.8T Jetta for an 02 BMW 330xi //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I know the Mk4 Jettas have a pretty tight spot for the battery. You can fit a pretty tall battery in that spot, or maybe put your AGM battery on its side? You will have to check measurements and compare to batteries online.

Another, better option would be to install a 2nd battery near your amp(s).

 

[soulnomad 10+ year member]

okay I have 3 g34 yellowtops (one under hood) at the moment...so finding a +220A alternator and installing one extra batt in the rear should be sufficient?

 

[VWBobby 10+ year member]

It would be plenty. It would give you at least 20A more than your theoretical maximum power requirement.

What a lot of people don't seem to realize is if you're not doing a continuous burp at max power, you're not going to require your whole charging system's capacity. The battery makes a good reserve that the alternator can charge up at the low parts of the music. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Now if you were doing a 20 second burp at maximum power, chances are you might drain the battery a substantial amount.

Remember, a 105AH battery means, 105 Amp Hours, or 105 amps per hour. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[sexy 10+ year member]

It would be plenty. It would give you at least 20A more than your theoretical maximum power requirement. What a lot of people don't seem to realize is if you're not doing a continuous burp at max power, you're not going to require your whole charging system's capacity. The battery makes a good reserve that the alternator can charge up at the low parts of the music. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Now if you were doing a 20 second burp at maximum power, chances are you might drain the battery a substantial amount.

Remember, a 105AH battery means, 105 Amp Hours, or 105 amps per hour. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

105 amps off a car battery for an hour is pretty misleading. The battery would have to be as big as a whole car and it would have to have a built in cooling system to deliver 105 amps for an hour.

 

[slim2fattycake 10+ year member]

hey guys, im trying to figure out ways to stiffen my charging system, im having crazy voltage dips and am trying to figure out what size HO alternator/combination of batteries would work best, thanks in advance! =]
Stock Alternator:90A

Battery:Optima Yellowtop G34 (had 2 in parallel, too much of a strain on alty)

Wiring:All 0/1 (big 3, All grounds double checked secure)

Idle:13.5V max (dips all the way to 10.4V on long transients)

Resting:12.6V

Total Current Demand :273A (3700rms and 40% stock current demand)

What amps are you actually running?

 

[90accordman 5,000+ posts]

What year Jetta is this? as i have a HO alternator for sale for a mk3

260amps max 160 idle its a DC Power alternator powdercoated Purple

 

[soulnomad 10+ year member]

**** dude.mk4 how much did that run you for mk3 just curious i got a quote for a 250A from dc a while ago...pretty scary price tag.

 

[slim2fattycake 10+ year member]

Which line did you ask about? If you asked about the XP line, then yeah its going to cost because its their top line.