Alt, batt, cap???

[Poundin'Metal 10+ year member]

Give me some feedbak here -- I finally found an alternator upgrade -- the ONLY alternator upgrade -- I have a Jetta w/ a 90 amp alt in it -- way not enough. The only thing better I can find is a 120 amp alt. I would like to be pushing 1500 watts -- my lights dim now at 550. The new alt is $233.65 plus tax -- is it even worth it for 30 amps? Would such a small jump even make a difference. My other option is a Xstatic BatCap 800 and a 35 farad capacitor. This runs $500. I don't have the money for the alt and the batcap and the cap -- what should I do?

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[xSomeguyx 10+ year member]

First, I'd look at re-assessing your power scheme. How many amps does your amp draw? Also, before you go upgrading anything crazy like your alternator, you may want to at least give the new system a try (you said you were running 550w now, but want to go to 1500w). That way, you'll know there's a problem.

Also, before you go blowing $100 on a cap, check out ebay, you'll find one a lot cheaper.

 

[n2audio 5,000+ posts]

Wow - problems with 550W?

Is it possible you have a weak battery causing a lot of current draw from the alt?? Bad connection somewhere?? I would expect 1200w or so off a 90A alt w/o any problems. One of the mods at SD is running 2kw+ off a 95A and it works fine.

And yes, I think a 30A upgrade is pretty significant. That's 30 unaccounted for amps, probably 1000 watts of music power, maybe more. Unlike your 90A alt - 40 or 50A of which is already being consumed by the rest of the elctrical system.

 

[Poundin'Metal 10+ year member]

C'mon -- help me out here...MTX tech. services says the addition of just a yellow top should do it -- but I don't believe them. Some feedback please.

 

[helotaxi 5,000+ posts]

Have you upgraded the block ground, battery ground and charging lead yet? If not start there. As n2audio said, the 30A upgrade is pretty significant. The MTX tech was blowing smoke. A battery will never stop dimming. It can't. It's 12V and the drop from 14.4V to 12V is your light dimming. The upgraded cables will get rid of that with your current setup. The combo of the alt and the cables will allow for a decent upgrade beyond what you currently have.

 

[pavengmike6 10+ year member]

I just fixed a problem with a system like you are saying. It sounds like your power system (power and ground wire) are not up to par. The system I just fixed is in a truck with a 90 amp alt. He was running 2000 watts and was getting headlight dimming. I ran a 4 gauge power and 2 different 4 gauge ground wires. (make sure you use 2 different ground spots)

What size wire are you useing? Do you have the old snake tounge ground (i mean are you using a connection tip, or did you strip off enough wire to wrap around a bolt)? If you do not use a good connection end you are only hurting you system.

With what you have now, you should not have a probem with headlight dimming. How old is your battery? Have you ever run you battery down all the way? If you did that you have a chance of buring a cell, and not getting the required volts out of the battery.