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DC Power 270a Only Making [email protected] On Escalade

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Brian:

When we clamped it, ALL positive wires coming off the alt (factory 4 gauge and big 3's 0 gauge) were run through the clamp meter. And we used the amp to put a large enough draw on the system that it *should* be putting out power. Voltage was dropping to 12.1 at the alt, so I don't think it's because of a lack of load. The d3100 is in the stock location and there is no rear battery at the moment.

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Makes sense Brian.

But how come is amp is shutting off from low voltage?

Installer error? LOL

thought you meant your amp, not his... in that case refer to my post about resistance below.

Edited by Audiofanaticz

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Brian:

When we clamped it, ALL positive wires coming off the alt (factory 4 gauge and big 3's 0 gauge) were run through the clamp meter. And we used the amp to put a large enough draw on the system that it *should* be putting out power. Voltage was dropping to 12.1 at the alt, so I don't think it's because of a lack of load. The d3100 is in the stock location and there is no rear battery at the moment.

Either way, that is still being a huge buffer on the system. since then the power wire runs from your alt to your battery, from your battery to your amp.. The battery is first in line of the path with least resistance.

Its a battery made to support easily 2 rf 2500bdcp before it even feels like its being stressed.

Another thing people dont think about is the voltage loss from a single piece of wire. 1 run of power wire will have a huge voltage drop, which in return results in less power output from the amp...

Mike singer uploaded a picture the other day, with 4 charge lines running from 1 alternator and people where baffled why does a single 300amp alternator need 1200amps worth of wiring.. the answer is simple voltage drop.

Here is Nick's response for the people who couldnt understand.

41550_661464708_1205682757_q.jpg
Nick Probst You

have to look at full path from alternator to amp. which we'll assume

thats 20 feet. if you did 2+ and 2- per alt so 200a per pair youd have

over a 1v drop from wire at full load. 100a per 1/0 pair drops you down

to only losing .5v from wire. Miikes rule of 100a per run of 1/0 is

definatly a smart idea, as you could buy 2 more 300$ batteries and not

gain .5v.

Edit, to go farther, nick is saying you have a good 1volt worth of voltage drop from the front of your charging system to the rear at your amplifier with 2 runs of positive and 2 runs of negative. i
Now if you only have 1 run of pos and 1 run of negative, expect even more voltage drop. More if your just running a single positive charge line to the rear, and not using something like the frame rail for a ground.

Edited by Audiofanaticz

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Hey guys. I just bought a new DC Power 270a alt, internally regulated. We clamped it and are only getting 170a at 2000+ RPM on a load. The amplifier is drawing the voltage down and cutting off after maybe 20 seconds because it isn't getting enough power. All Shok 0-ga, big 3 done, D3100 battery with RF T2500bdcp amp on two 18s.

Since you overlook the obvious, let me point that out for you.

You have a 270amp alternator.

You have an amplifier that draws 300amps max.

You have a D3100 battery that is capable of 5000amps max, and can easily provide 1000+ amps continuously over the length of your clamp testing done on your alternator.

Do you see where Im going with this?

An alternator is not made to charge the batteries, its made to maintain them. The alternator will only work as hard as they need too.

Your amplifier is pulling as much as 300amps of current on a solid test tone from such a big battery and your alternator is not going to need to work hard.

You remember back in the day with discmans, and how you had that 30second antiskip? Where the CD is being read 30seconds ahead of the time then the music your hearing in your ears.

Think of that big d3100 battery as the antiskip feature on that diskman, that battery is giving you a huge reserve time, where the alternator is not needing to work at full load.

If you cant create the current demand needed to drain your battery reserves, then that battery is being a huge buffer in your electrical system (which is what they are designed to do). Not to mention that Im sure your d3100 is the battery in your rear, and you also have a stock battery under the hood of the vehicle, which is creating even more of a buffer..

Current pulls from the path with least resistance. Your rear battery has a shorter power wire running between your amp and battery, so most of your amps power is going to pull from that battery, before it even thinks about going thru that 18+ feet of power wire that runs to the front of your truck where another battery is.

Another thing most people forget to do is also clamp your factory charge wire on the alternator along with your 1/0gauge power wire you added to it when you did your big 3 upgrade.

That factory wire can support an add 20-50 amps of current, and if you left the factory wire connected (like you should), theres going to be additional current flowing there that is not being clamped.

So if you want to officially get a legit clamp on your alternator you need to clamp all the power wires that are bolted to it, and you need to either A) create a higher current demand then what all your batteries can support, or B) disconnect the d3100 and wire your amps power directly to the power wire that runs to the front, and even at this point, your factory battery will still create somewhat of a buffer and hinder your clamp test results but not as bad as a d3100 would.

This goes for any brand alternator out there, if you can not create more load then your batteries can support, or disconnect those batteries, you wont get accurate clamp results.

Great writeup. I was going to derail the thread with "remember the phonograph record?" but I'd simply be dating myself! Good info.

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Agreed about voltage drop on the wire. We were seeing 12.1v at the alt(one probe to the terminal, the other to the casing) and 11v at the amp(reading from the inputs).

The alt should be kicking up the power to keep a constant voltage right? You'd think that you shouldn't need to drop down below 12v to get power from the alt. Especially since I have the same alternator and I've clamped mine doing just over 200a at idle at 12.3v - his doesn't even do that while revving and we both have 270XPs. That's why this is so baffling.

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Was talking about his amp lol

Just missed the h


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And then he gets to say ok all you guys were right. im sorry for being a dummy poo poo head.

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Agreed about voltage drop on the wire. We were seeing 12.1v at the alt(one probe to the terminal, the other to the casing) and 11v at the amp(reading from the inputs).

The alt should be kicking up the power to keep a constant voltage right? You'd think that you shouldn't need to drop down below 12v to get power from the alt. Especially since I have the same alternator and I've clamped mine doing just over 200a at idle at 12.3v - his doesn't even do that while revving and we both have 270XPs. That's why this is so baffling.

Not necessarily, and if your having things such as resistance, your not going to see said voltage.

The lack there of wiring to the amp is already hurting things, so any benefit that your alt could see will not be seen.

Lets face it, your batteries are 12volt, d3100s normally rest 12.9 on a good charge, without being drained. Its not the alternators job to keep the batteries charged at 15volts like most highout put alts do with no load on them.

I have 3 alternators on my truck, 2 270xp, and a 390xp.

With running my 2 saz4500s @ .35ohms each, with two 4yearold d3100s, and a smaller c&d under the hood, I dropped to the low 11volt marks, sometimes 10.9s.

When I wanted to clamp my alternators, I had to unplug 2 of the alternators, and clamp each alt by itself, along with disconnect one of my d3100s to be able to get a full legit load on my alts, and still was not able to fully load down my 390xp.

IIRC my 2 amps wired at .35ohms each pulled somewhere around 1100amps of current playing music.


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Brian:

When we clamped it, ALL positive wires coming off the alt (factory 4 gauge and big 3's 0 gauge) were run through the clamp meter. And we used the amp to put a large enough draw on the system that it *should* be putting out power. Voltage was dropping to 12.1 at the alt, so I don't think it's because of a lack of load. The d3100 is in the stock location and there is no rear battery at the moment.

Either way, that is still being a huge buffer on the system. since then the power wire runs from your alt to your battery, from your battery to your amp.. The battery is first in line of the path with least resistance.

Its a battery made to support easily 2 rf 2500bdcp before it even feels like its being stressed.

Another thing people dont think about is the voltage loss from a single piece of wire. 1 run of power wire will have a huge voltage drop, which in return results in less power output from the amp...

Mike singer uploaded a picture the other day, with 4 charge lines running from 1 alternator and people where baffled why does a single 300amp alternator need 1200amps worth of wiring.. the answer is simple voltage drop.

Here is Nick's response for the people who couldnt understand.

41550_661464708_1205682757_q.jpg
Nick Probst You

have to look at full path from alternator to amp. which we'll assume

thats 20 feet. if you did 2+ and 2- per alt so 200a per pair youd have

over a 1v drop from wire at full load. 100a per 1/0 pair drops you down

to only losing .5v from wire. Miikes rule of 100a per run of 1/0 is

definatly a smart idea, as you could buy 2 more 300$ batteries and not

gain .5v.

Edit, to go farther, nick is saying you have a good 1volt worth of voltage drop from the front of your charging system to the rear at your amplifier with 2 runs of positive and 2 runs of negative. i
Now if you only have 1 run of pos and 1 run of negative, expect even more voltage drop. More if your just running a single positive charge line to the rear, and not using something like the frame rail for a ground.

Here is what I don't get about that whole post, cuz in my truck I am running similiar setup on runs of 1/0 and I have half as much wire as what he has per alt and I don't drop even .1 volt so where is he getting this 1 volt rule? And my 1/0 runs are 25 ft long to my battery bank in the bed of my truck.

Edited by AMI CUSTOMS

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To add to what Chris said, the system had a 200a fuse on the positive line between the battery and amp and it never blew in six months time. Not once, and I drive around at full volume a lot. Today, that fuse finally blew when I revved the engine to 4500rpm with the stereo cranked at full volume. So, it is reasonable to assume that the alt has never put more than 200 amps of current through the line from the battery to the amp in six months. Surely in six months time, that system should have at some point, pushed more than 200 amps of power to a t2500bdcp at full volume if the alt was working properly.

What it boils down to, is that if the alt was working properly, either the amp would not be going into protect after 20 seconds at full volume, or the fuse would have blown long ago.


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