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Discussion Starter · #1 ·
I'm trying to put in a Alpine MPR-M2000 or PDX M12 to power two Alpine SWR-1043D 10" subs. Theres alot of power in those amps but I'm trying not to have to have duel batts or install a HO alt. What can I get away with when I comes to our trucks?
 

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Discussion Starter · #2 ·
Maybe just doing the "big three" and using a cap instead of spending the money on a HO alt.?
 

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At 2,000 RMS you should be ok with just the big 3, but that would be my limit. Anything above I'd add another battery.
 

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Discussion Starter · #4 · (Edited)
The amp I want is 1500W RMS. It would suck though...if I bought it and installed it only to find another battery or HO alt. is needed. How do you even know if the stock charging system would be enough?
 

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No I don't believe it will be enough not if you drive your system as hard as I do. I have the Big 3 and an Optima Yellow top and if I drive my amps (Sundown 1200d and Sundown 100.4) hard enough my voltage will drop to low and shut the sub amp off.
 
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I think different alternators came with different trucks, this is the one that came with mine:

Hitachi alternator:

LR1130-701
12v-130A nominal rating
Negatvive ground polarity
1,200 RPM Minimun revolution under no load (when 13.5 volts is applied)

Hot output current (when 13.5 voltage is applied)

More than 78A/1,800 rpm
More than 108A/2,500 rpm
More than 130A/5,000 rpm

14.1-14.7V @ 25C regulated output voltage

6mm (0.24 in) minimun length of brush

1.0-3.432 N (0.102-0.3501 kg. 0.22-0.7715 lbs) brush spring pressure

26mm (1.02 in) Slip Ring outer diameter

2.1 ohms Rotor (field coil) resistance

Then you can figure out the current draw by knowing your amp efficiency and using the equation Power (in watts) = Volts x Current (amps)

Or you can take the easy way out and go here:


http://www.bcae1.com/images/swfs/systemdesignassistant.swf

Which tells you that a 1500 watt class D amp driven to clipping will draw around 136 amps
 

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Discussion Starter · #7 ·
I think I'll get something thats a little less power hungry. A 600W amp shouldn't give me any problems.
 

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You can still use that Amp, if that is an Amp you like. Just don't pump the volume as much as it is capable of doing. All else being equal (Amp Efficiency, Good Wiring etc), the Amp will only draw what you demand it to draw (Volume setting).
 

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Watch your battery terminals, you will corrode the positive terminal extensively with the stock battery, alternator and high powered amp if you don't protect them.
 

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Discussion Starter · #10 ·
I would like the larger system ($712) but I think the lesser system ($480) will work better without having to mod my charging system. I still have 3 months until I buy it so I might decide to go with the bigger system when the time comes. I wouldn't plan turning the gain very far past half on the larger amp...would I still be good with the big three and a yellow top? Not having to worry about not turning my volume very high in fear of the amp cutting out would kinda get old....

I've already replaced the stock battery (not a REAL good one...) and the stock pos battery term. That terminal didn't last very long after I installed my current amp.
 

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No I don't believe it will be enough not if you drive your system as hard as I do. I have the Big 3 and an Optima Yellow top and if I drive my amps (Sundown 1200d and Sundown 100.4) hard enough my voltage will drop to low and shut the sub amp off.

You have a different problem then. With my big 3 and 1 SVR under the hood with my old AQ 2200D @ 1 ohm and DC 175.4 I had no problems, at full tilt voltage barely dipped below 13.0. Of course adding a second battery helped, but you shouldn't be having those problems. Plenty of people run 1500-2000 on stock electrical with the big 3 and a decent battery.
 

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I am probably running close to 1900 rms power between my amps my peak draw is probably 3000+ watts. I have 0 gauge power and ground with 0 gauge Big 3 wiring I know that I am requesting to much of my electrical system.:teethmast
 

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I am probably running close to 1900 rms power between my amps my peak draw is probably 3000+ watts. I have 0 gauge power and ground with 0 gauge Big 3 wiring I know that I am requesting to much of my electrical system.:teethmast

You do realize that the 2 amps I listed are pushing 3k+ RMS at 14.4v? My big 3 is all with 2/0 welding cable, and a pretty decent sized SVR AGM under the hood at the time. Now I'm running 2 runs of B+ and 2 runs of - 1/0 welding cable to the back to 2 more SVR's running my DC 3.5K and my DC 175.4.
 

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It depends on how much power you are actually drawing when listening to the stereo and at what RPM the alternator is spinning. Adding a second battery will help with transient high amp draws, but if you are consistently outdrawing the alternator, it will drain the batteries, and then the alternator has to charge the batteries in addition to running the truck and stereo. Batteries and/or a cap do not compensate for consistently outdrawing the alternator.

If you have access to a DC clamp meter, you can tell exactly what is going on. With the stock alternator and a TRU 4.100 and TRU 2.100 both cranked driving two sets of comps and one 10" sub, my stock alternator could not keep up at idle. If you have a helper, you can tell exactly what is happening at various RPMs by clamping the wire from the alternator and then clamping the main power cable to your (amps).
 

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Yea at 13.2 volts-1900 watts rms I am pulling 144 amps. If my voltage drops close to 10 volts on a hard pull, and I am pumping out all my amplifiers can give which I would assume 3000 watts I would be using 300 amps of power. Either way the amps rms load on the electrical system is more than my alternator can supply.
 

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Yea at 13.2 volts-1900 watts rms I am pulling 144 amps. If my voltage drops close to 10 volts on a hard pull, and I am pumping out all my amplifiers can give which I would assume 3000 watts I would be using 300 amps of power. Either way the amps rms load on the electrical system is more than my alternator can supply.
How did you tune your amps? If you didn't use an o-scope you could be clipping which would cause it to pull more than normally.
 

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Discussion Starter · #20 ·
this link does not work it says page not found
Sorry...link works for me. Heres what the post says.

Since this question comes up again and again here, I thought this might be a useful post. Performing a "Big 3" upgrade on your vehicle is one way to improve the electrical system performance and its ability to supply power to your audio system. This upgrade will help any vehicle using an after-market amplified stereo system, and most certainly should be performed on any vehicle after a high-output alternator is installed.

Please be sure you read and understand this entire instruction before you begin.

Definition: the "Big Three" upgrade means improving the current capacity of three cables: 1) alternator positive to battery positive, 2) battery negative to chassis, and 3) engine ground to chassis. Some people replace the factory wiring; others add additional cables to the factory wiring. This instruction is to add cables to existing OEM wiring.

Parts and Tools:

As a minimum, you will need to purchase the following:

• Sufficient length of high-strand count high capacity power cable.
- The length required differs for every vehicle. You can measure the length of the existing cables and buy the same length, or contact your dealer or a mechanic and ask, or sometimes you can look it up in a manufacturer's wiring book, or guess. If you guess, make sure you over-estimate and buy too much.
- High strand count cable is more flexible and more reliable than low-strand count cable. Never use solid-core wire in a moving vehicle as it will eventually break.
- The gauge of wire you need depends on the total current draw of your audio system, and/or the current generating capacity of your alternator. Never use smaller cable that you used to power your amps; never use smaller cable than what already exists in your vehicle; never use smaller cable than the generating capacity of your alternator; never use smaller than 4 AWG (it's just not worth the time to use anything smaller); if in doubt, always use higher gauge cable than you think you need. If you look at the Power and Ground charts and your amplifier current draw corresponds to 2 AWG cable, use no smaller than 2 AWG cable, and use 1/0 if you can.

• 6 ring terminals or lugs of the appropriate size for the cable chosen. Two of these need to be large enough to fit over your battery posts, or appropriately sized to bolt onto your existing battery terminals.
• 1/2" or 5/8" shrink tubing (or some other form of permanent electrical insulation. Tape is NOT recommended.)
• Cable ties (plastic zip ties.)

• Wire cutters large enough to handle the cable you choose.
• Crimpers large enough to handle the connectors you choose.
• Soldering iron or gun.
• Solder.
• Scotch brite and/or a small wire brush.
• Heat gun.
• Safety razor blade (or other tool for stripping cable).
• Heat gun (if using shrink tubing).
• Wrenches for removing bolts in your vehicle.

Procedure:

1. Make sure your engine is completely cool before beginning. Identify the three cables being replaced. Make sure you can reach both ends of all cables. NOTE: the engine block to chassis cable may be between the engine and the transmission, or connected to the transmission and the fire wall, and is often an un-insulated flat braid cable.

2. Determine the lengths of cable needed to reach between the three locations being upgraded. Be sure you measure with a flexible tape (a tape measure used for sewing works great) and record the total length along the path you intend to install the cable. You do not want your cables to be pulled tight between any two locations as things move and vibrate as you drive. Be sure to include at least 1 inch extra for slack. NOTE: there is no reason to copy the existing wiring layout in your vehicle unless you want to. Also, be sure that the path you choose does not follow or lay across anything that gets hot, like exhaust parts, or anything that must move, like throttle linkage.

3. Cut your new cable to the three proper lengths. NOTE: some people like to use red cable for positive and black cable for negative. Doing this is completely up to you and is nice, but not necessary. You can use cable with any color insulation you like.

4. Strip each end of all cables to the proper length for the terminal lugs being used. NOTE: after full insertion into the lug, a small "band" of bare wire is usually seen between the back of the lug and the beginning of the cable insulation.

5. Begin at any one end and insert the stripped cable into the lug. Make sure it is fully inserted. Crimp the connector to hold the wire in place. NOTE: crimping large cable can be difficult. The intention here is not to make the crimp the sole means of holding the wire, but only to make sure the lug does not slip around during the soldering phase. I do NOT recommend using hammers or pliers or vices to crimp the connector as over-crimping can break the strands of the cable, reducing the current carrying capacity. Do not over-crimp.

6. You may need to use a vise or some other set of "helping hands" to hold the cable while you solder it. Heat your soldering iron and place it on the connector (on the lug side) barrel. Hold a piece of solder against the tip of the iron and melt the solder into the strands of the cable. Use sufficient solder to fill the connector and completely cover all strands of the cable. NOTE: the lug will get hot and will burn you if you try to hold it. Also, if the insulation on the cable starts to melt, you are over-heating the cable and not paying attention to melting the solder into the cable. You do not need to try and melt the cable!

7. Repeat the above steps on each end of all three cables.

8. After the cables have completely cooled, cut a piece of shrink tubing long enough to cover the soldered barrel end of the lugs and reach about 1/2" onto the insulation of each cable end. Slide this over each lug and use a heat gun to recover the tubing in place.

9. Disconnect your battery, starting with the negative cable first then the positive cable. Discharge any caps you may have in the system.

10. Begin adding your new cables along side the existing ones. I usually begin with the alternator positive cable. Locate the output stud on your alternator and remove the nut. Slip the new cable onto the lug and replace the nut. There is no need to disturb the existing cabling. Route the new cable to the battery and position it to connect to the positive battery post (or connect it to the positive terminal on the OEM wiring) but do not connect the battery yet.

11. Secure the new cable in place by using cable ties every 6 to 8 inches. Secure the cable to cool non-moving parts!

12. Locate where the negative battery cable attaches to the vehicle chassis. Remove this bolt and the OEM battery cable, and clean the mounting area of the chassis using scotch brite and/or a wire brush. Make sure there is no dirt, rust, paint, undercoating, etc in this location. You want bright shiny metal. Connect both your new ground and the OEM ground back to the chassis. NOTE: Some people like to create a new ground location by drilling into the chassis and using a bolt with star lock washers for the new ground cable. Route this new cable back to the battery and position it to be attached, or connect it to the negative terminal. Do not reconnect the battery yet.

13. Secure the negative cable using cable ties every 6-8 inches. Again, don't tie it to anything that moves or that gets hot!

14. Disconnect the engine ground strap at both ends. Using the wire brush or scotch brite, clean both the engine block and the chassis as you did for the first ground strap.

15. Line up the lugs on both the OEM ground strap and your new ground cable, and use cable ties to secure them to each other. This is much easier to accomplish in your lap or on the floor than it is while lying under your car or hanging upside down in the engine compartment. Reinstall both cables at the same time using the factory bolts.

16. Double check to make sure all bolts are tight. Be careful not to over-tighten them as you don't want to strip anything! Also, on some factory alternators it is WAY too easy to twist off the positive output lug. If you break it off, well hell, you really wanted a high-output alternator anyway, right? It is also a good idea at this point to measure resistance of the new cables. Take an ohm reading between the battery end of the new ground cable and the engine block. It should read less than one ohm. Also check between the alternator bolt and the disconnected positive battery terminal, which should also be less than one ohm. If you read too high resistance, double check all connections and make sure you do not have something c**ked sideways or hanging loose.

NOTE: Realize that the "absolute ground" of the electrical system is not the battery negative terminal or the vehicle chassis, but is the case of the alternator itself. This is why perhaps the most important cable among the Big 3 is the engine ground strap, as this is what connects the alternator ground to the vehicle's chassis. Be certain the resistance between the alternator case (the engine block assuming the alternator is properly bolted to the engine) and the battery negative is minimized. (Thanks to the12volt for pointing this out!)

17. When you are sure you are done and anything in your system that you may have disconnected are re-connected, clean your battery posts and reconnect the positive battery terminal first, then the negative one.

18. Start your vehicle. Hopefully the engine starts. :) Examine the engine compartment and make sure none of your cables are getting hot or are vibrating or shaking around. If they are vibrating too much you may need to relocate them or use more cable ties. If you see smoke, immediately shut off the car and disconnect the battery. Seek help. :)

19. Assuming all looks good, take a voltage reading at your amplifier and ensure you read 13.8 (or higher) volts. This indicates a properly operating charging system.

20. Now'd be a good time to turn it on and make sure it sounds good! Then of course log onto the12volt.com and post that you have upgraded your Big 3!
 
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