Yo Luke - what's your take on those big capacitors?

[george graves]

That was more my question - for getting rid of RPM based lows that seem to happen to these older cars. No one seems to have a lot of first hand experience.

[browntown]

George you have a m30 don't you? Put a b35 140amp alternator on there.

[george graves]

Hmmm. I'll have to check what I have. I have a m30b35.

[browntown]

Does it have a big air cooling duct on the alternator? Thats the 140 version. I used an old m20 alternator as a core for a big 140amp one at autozone.

[StereoInstaller1]

Fuck it, HID don't flicker in my car at 140ish DB, drawing well over 80A on an 80A alternator.

[browntown]

This is what happens when I don't call you back right away? Angry Luke

[u3b3rg33k]

On an E30? 2 choices: put a cap on the headlights or go HID.

A cap anywhere in the system (like on the battery), will help with sudden loads, it doesn't have to be at the end destination (and if you did, it would blow the fuse when you turned on the lights).

I still like the pretty lights...

Seriously, on a car with the battery in the trunk they are pretty silly.

I use them as distribution blocks and as voltage displays.

I couldn't disagree more. Trunk battery means it's easier to wire in the capacitor. I can only imagine how much my battery and alternator prefer to have a capacitor when I plug the air compressor into my 1500W inverter and turn it on. A 1 farad capacitor has enough stored energy to start (but not run) a small "1hp" rated air compressor.

Capacitors are only of use for sudden loads, like the moron who runs his house off of his e30 when the power goes out. I can watch the voltage gauge drop when I plug in two refrigerators at the same time, it's a much softer hit on the car electrical system when I have a capacitor wired in. By the way, you can use a 24V inverter if you have two cars wired in series with (00 AWG) jumper cables. What kind of moron would do that? Oh right, that'd be me...

[StereoInstaller1]

I couldn't disagree more.

Hmmm...well, lets see...your "disagree" versus my having installed well over 100 caps in cars with big systems, and not having seen much change...hmmmm.

I guess that whole "30 years of experience" and "professional" thing doesn't carry much weight compared to your "engineering student" thing, does it?

[kinvodA]

Hmmm...well, lets see...your "disagree" versus my having installed well over 100 caps in cars with big systems, and not having seen much change...hmmmm.

I guess that whole "30 years of experience" and "professional" thing doesn't carry much weight compared to your "engineering student" thing, does it?

Oh SNAP! I've learned to not disagree with Luke, especially when it comes to stereos in BMWs. When my previously "knowledge" doesnt line up with what Luke is saying, his explanation clears up the issue for me and sets me straight and makes sense.

[u3b3rg33k]

"seen much change"

You're not going to see that much change if you're watching headlights (thermal mass), a dvom (slow), or an old VOM (mass). Try an oscilloscope.

As for throwing caps at cars, it's part of a system. Capacitors don't solve too small of an alternator, or wires that are too small. They can help compensate for cheap amps, or stupid loads like those you'd see when you turn on a refridgerator (160A draw for a half second is a lot more than most amps will pull at the terminals).

[StereoInstaller1]

"seen much change"

You're not going to see that much change if you're watching headlights (thermal mass), a dvom (slow), or an old VOM (mass). Try an oscilloscope.

As for throwing caps at cars, it's part of a system. Capacitors don't solve too small of an alternator, or wires that are too small. They can help compensate for cheap amps, or stupid loads like those you'd see when you turn on a refridgerator (160A draw for a half second is a lot more than most amps will pull at the terminals).

This, Ladies and Gentlemen, is why those of us with actual experience think college kids are retards.

[KennyT]

Luke, what should theoretically happen is what he's mentioning. The real question is if they do anything. I would really like to see a scope hooked up at various points in the system, just to put hard data behind your experience.

Personally, only systems I've ever worked on were cheap, low quality, loud systems. The amps were probably way overdrawn, and they sounded like ass. They were all in friends cars.

[StereoInstaller1]

Luke, what should theoretically happen is what he's mentioning. The real question is if they do anything.

Obviously...but the talk of how well they work to fire up a freezer or whatever is just retarded...way too many books, way too little time actually DOING stuff.

And just so you know, I got my first 'scope when I was 12.

That would be 1975. Long long ago, in a galaxy far away.

We used a better one as a tachometer (three phase self triggering) on our local slot car track (GP 12, 20, 27 and open class Wing cars) and found our ideal gearing with that knowledge.

I am well versed in theory too, but it is pointless and useless. George knows his shit, if he wanted that kind of info he would haver done his own research. Instead he specifically asked me to address the issue.

And George, just for that I am gonna burn this motherfucker DOWN!

oh yeah...I still like the pretty lights.

[KennyT]

oh yeah...I still like the pretty lights.

At least that is what is important.

Give my fellow student time, eventually he will realize the books and classes he has paid for don't teach you much.

[darrenforeal]

Hmmm...well, lets see...your "disagree" versus my having installed well over 100 caps in cars with big systems, and not having seen much change...hmmmm.

I guess that whole "30 years of experience" and "professional" thing doesn't carry much weight compared to your "engineering student" thing, does it?

+1

Obviously...but the talk of how well they work to fire up a freezer or whatever is just retarded...way too many books, way too little time actually DOING stuff.

And just so you know, I got my first 'scope when I was 12.

That would be 1975. Long long ago, in a galaxy far away.

We used a better one as a tachometer (three phase self triggering) on our local slot car track (GP 12, 20, 27 and open class Wing cars) and found our ideal gearing with that knowledge.

I am well versed in theory too, but it is pointless and useless. George knows his shit, if he wanted that kind of info he would haver done his own research. Instead he specifically asked me to address the issue.

And George, just for that I am gonna burn this motherfucker DOWN!

oh yeah...I still like the pretty lights.

I too have done a lot of installs on high and low end systems with and without a cap. Granted not like Luke but still. Does it make a noticeable "real world" difference? NO. The end. But for god sakes if you must use one don't get a 1 farad one.

Also, I haven't been around this board that long but it is easy to tell Luke knows his shit backwards and forward. And theory and application are worlds apart in car audio.