help with planning my quad-alt setup

[merzbow 0]

So... I just ordered four XP 270 alts and a bracket for my Tahoe. For batts I've got an S3400 for the front and four D3100s for the back. To start with I'm planning on running 10kw to the subs, maybe 1100w to components. So I need wiring advice. Do I:

1. Run the positives from all four alts to the S3400 positive post, then go from there to the D3100s (which will be connected with a bus bar)? This is the "single pool of power approach".

Or:

2. Run the positive from one alt to the S3400, then run the positives from the other three alts to the D3100s. This approach completely isolates three of the alternators and the four D3100s, which will be used exclusively to power the sub amps. The other alt and the S3400 are used for everything else in the vehicle.

On the phone Kyle suggested option 2, but I didn't entirely understand why. Kyle if you're reading this can you elaborate? To the layman it would appear option 1 would be better because with option 2, I imagine much of the power of one of the alternators could go unused. Don't the voltage regulators in the alts ensure that 14v (or whatever) is always being produced?

[sefugi 166]

Option 2 sounds like a lot of power for the vehicle. With option 2 maybe he was thinking that you would run the 1100 watts for the components off the front alt. and bat. along with running the vehicles needs.

[merzbow 0]

Option 2 sounds like a lot of power for the vehicle. With option 2 maybe he was thinking that you would run the 1100 watts for the components off the front alt. and bat. along with running the vehicles needs.

Yes, I should have made that clear; since the component amps would be somewhere in the back of the car also I would have to run a wire for them specifically from the S3400. Now that I think about it I suppose 1100w is a good deal of power on its own (potentially 80+ amps), although since it's components I probably won't ever be able to hit 1/10th of that without going deaf, lol. I also recall Kyle saying something about the control wire from the vehicle potentially "confusing" the other alternators...

[merzbow 0]

So I got the alts (build thread here), and they look great. I have a few questions (emailed Kyle but haven't heard back yet).

1. The relay has a long fused red wire and a white wire coming from it. I assume the red wire goes to a free ignition switched slot in the fuse box, and the white wire to ground?

2. Each of the three connectors has a red wire and a blue wire. Where do I attach these?

3. Any tips on routing the new belt? I assume it's important to get as much "coverage" around each pulley as possible? Is there a rule of thumb for how much of each pulley I should cover in order to avoid slippage (40%, 60%, etc.)?

4. If I wanted to run a ground wire to an alt, where do I attach it?

From digging around I believe I have answers to all 4 (1 - yes, 2 - both on output stud, 3 - do your best and see what happens, 4 - on the "ear" bolts), but I really want to be sure before risking equipment.

[sefugi 166]

That's a sweet lookin' setup!!!!

Didn't the alts/bracket come with a routing for the belt? By looking at the bracket I can visualize how the belt should go... The alts don't have a ground stud on them?

Checked out your build, damn that's a lot of sound deadener!!

[DC Power Kyle 21]

Belt routing

relay harness: https://support.dcpowerinc.com/index.php?/Knowledgebase/Article/View/4/0/installation-guide-for-relay-harness-with-blue-sense-wire

ground studs on alternators aren't needed... the alternator itself is a grounding point if it was needed OEM manufactures would do it as well :laughs: ground anywhere to the bracket, engine, back of the alternator where the mounting holes are, or wherever else you can get some grounds on.

[merzbow 0]

Lol, I completely missed that you guys had a knowledgebase section on your web site. Going to go through it in detail...

The pic definitely helps, thanks.

[DC Power Kyle 21]

No problem. More pics of the quad kit are on our facebook.

[merzbow 0]

That's a sweet lookin' setup!!!!

Didn't the alts/bracket come with a routing for the belt? By looking at the bracket I can visualize how the belt should go... The alts don't have a ground stud on them?

Checked out your build, damn that's a lot of sound deadener!!

I fixed the pic.

Edited August 8, 2011 by Merzbow

[merzbow 0]

OK Kyle, with my GM service manuals in hand I've been reading up on the charging system in this vehicle in preparation for the immense amount of work I have to do here. You probably know all this already but I just want to state it for my own understanding. Tell me if I'm wrong anywhere, please...

Guess what this is (2011 Chevy Tahoe):

That's the "battery current sensor" clamp. It fits around the negative cable from the battery to the frame. (Actually, there are TWO negative cables, a big one to frame and a small one apparently just for the headlight assembly return path, but whatever.) This sensor feeds into the BCM (body control module), which also measures voltage. Using these data, the BCM controls the alternator (by adjusting the field current supply, I think).

This is a problem if we want to upgrade that cable as part of installing a high-output alternator. Just keeping the OEM cable connected and running a new 1/0 cable is NOT sufficient because the clamp will NOT see the current running through the new cabling. Basically, this current clamp must see all current being returned to the battery (that is connected to the OEM alternator) for the alternator to be controlled properly. Luckily, it appears this clamp will fit around a 1/0 cable. (The OEM cable is apparently 4-gauge.) So I think I can just do a straight-replace on that cable.

Note that there is no way this clamp would fit around MULTIPLE negative cables, nor is there any way to have the BCM control more than one alternator. Which I suppose is why you recommended I completely isolate the extra alternators and their batteries. However, since I'm also replacing the OEM alternator with a 270XP, I need to upgrade the OEM battery and cabling, hence this worrying.

So am I right in assuming I can just straight-swap the OEM 4-gauge negative with 1/0, fitting it through the OEM current clamp, and magic will happen?

[merzbow 0]

After waking up I realized I wasn't quite accurate. The alt is of course not grounded directly to the battery, it's grounded to the frame or engine, and that negative battery cable is also grounded to the frame/engine. So the current clamp doesn't see current returning to the alt, only current returning to the battery. This means it only sees battery load. Doesn't change the conclusion though, you should still upgrade that to 1/0.

[DC Power Kyle 21]

From what I read it seems you got it figured out. If you have any more issues just shoot me an e-mail at [email protected] or call me. Always the best way to get ahold of me

[merzbow 0]

Got the first alt installed:

http://www.*****.com/board/topic/114410-2011-chevy-tahoe-10k-watts-4-fi-btl-15s-4-dc-power-alts/page__view__findpost__p__1644898

Too sexy. Surprised that you guys can go with such a small pulley yet still provide such a high idle output. Anyways tomorrow I plan to throw on the entire quad-alt kit (although the alts will just be running as dummies without the harness attached, I don't have my sub stage battery bank or 1/0 back runs installed yet).

And BTW, god damn that is sexy. (Worth mentioning again.) Kudos to your powder coater. And as promised I will find a unique way to work the DC Power logo or name in this area somehow.

Edited August 12, 2011 by Merzbow

[DC Power Kyle 21]

You mean go without such a small pulley?

Glad you liked the powder coating! Enjoy!

[merzbow 0]

You mean go without such a small pulley?

Glad you liked the powder coating! Enjoy!

Well it's definitely a good deal smaller than the stock alt, but I imagine some competitors of yours must be going even smaller, given the complaints on their forums about idle performance. (Not that I'm naming any names, heh.) Anyways it's all the same to me as long as it works.

[merzbow 0]

http://www.youtube.com/watch?v=5wiuS-KEbD8

No problems in the end that I couldn't fix with a Dremel and an angle grinder (see the build thread, heh.) Nothing blew up, shattered, caught on fire, or otherwise summoned demons from an alternate dimension. (Actually I was kind of hoping for the demons, but oh well.) No harness or wires hooked up yet so right now all they do is spin and look pretty.

[DC Power Kyle 21]

Looks very badass.

FYI we could run stock size pulleys and still see 160-170 at idle.. but 190-210 is always better

Why didn't the belt work for you?

[merzbow 0]

Looks very badass.

FYI we could run stock size pulleys and still see 160-170 at idle.. but 190-210 is always better

Why didn't the belt work for you?

It did work in the end (and quite well, final tension ended up to be very close to OEM), there were just two bolts in the way, both relatively easy to fix with Dremel/angle grinder:

Bolt 1:

Bolt 2:

It wasn't a big deal, everything about this is highly custom and there are so many vehicle variations, so I didn't come into this with the expectation that everything would be a perfect fit from the get-go. But in the future you may want to look into moving the top pulley a tad (there is a second hole for it but that puts the pulley right on the bolt) and providing a shorter-head bolt for that bottom location (or insetting that bolt hole into the bracket a bit). Overall I'm very impressed, there are ZERO clearance issues with the alts as they sit, everything seems solid. All that's left is to get to the point where they are providing power and see what they can do.

Edited August 13, 2011 by Merzbow

[DC Power Kyle 21]

Glad to hear things went pretty smooth. I'll relay the bolt information on to dave. If the gates green belt works, run that over the black belt.. they're a lot stronger.

[merzbow 0]

http://www.youtube.com/watch?v=LFYfGpUpTGo

Fixed the bracket alignment by putting a washer under each of the three bracket bolts, pulleys all now line up. Also got the new "Green Line" Gates belt in. The roughness I was experiencing when revving from low RPMs while moving is now greatly reduced. After some driving, the tension ended up a bit tighter than the OEM position, but not near maximum tightness. Now when I put the belt on, it was near maximum tightness. I think this is just due to simple physics - objects will take the path of least resistance - driving around and having the belt rotate will automatically cause it to "optimize" its path around the idler pulleys reducing tension as much as possible. I have no complaints here, in fact if it was any shorter, there was NO WAY I could have gotten it on in the first place. As it is, I had to loosen all the bracket idlers and remove one of the OEM idlers (temporarily) to do so.

Anyways, I have all the 1/0 hooked up to the alts, and the harness hooked up, but the harness is not powered yet because I don't have my battery bank installed (or any amps or subs for that matter, lol). Going to be interesting to see how they perform when I finally get music playing at max. I suppose if there's belt slippage then, I will be hard-pressed to hear it with 10k watts of sub stage crushing my eardrums, heh...

Edited August 25, 2011 by Merzbow

[swagger_wagon468 53]

VERY SEXY ALTS! Did you absolutely need all four alts for 10k watts? Or are you trying to stay above 14v at full tilt? Reason I ask is because I can only fit one alt in my car and was gonna go with a single 390xp. But I will be running 10-12kwatts as well. I hope it will be enough. Lol

[merzbow 0]

VERY SEXY ALTS! Did you absolutely need all four alts for 10k watts? Or are you trying to stay above 14v at full tilt? Reason I ask is because I can only fit one alt in my car and was gonna go with a single 390xp. But I will be running 10-12kwatts as well. I hope it will be enough. Lol

270*14*3 = 11340 so the alts should be providing just enough power at full-tilt RMS to not draw from the batteries. This is, of course, at ideal RPM and assuming very efficient amps, so in real-word scenarios batteries will still be drawn upon a bit, I imagine. In your scenario you will be relying a lot more on battery power, so load up on the D3100s (I have 4, you should have AT LEAST 4, but ask on their forums).

[DC Power Kyle 21]

Looks amazing!