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Duramax with Sound System needs 3 batteries?

8K views 10 replies 6 participants last post by  2500-HD 
#1 ·
Hi all....

I have a 2004 GMC Sierra 2500HD. I have about a 2500-3000 watt sound system and I removed one of the acid batteries (standard battery) and replaced it with an XS Power D3400 AGM Battery. These are popular for sound systems as they are powerful enough to act like a capacitor as well.

The issue I am seeing is that if I am driving and listening to my system loud, I feel the transmission shifting harder/rougher. I go back and play the same song but lower it this time and drive again and the shifting is fine. No issues. So I am wondering if my 2 batteries is not enough or correct for the truck to function correctly? Not sure if anyone has seen this before. Do I need to add back my old battery and then possibly add the AGM battery as well on a bracket hidden somewhere under the truck? I have done the big three upgrade and have a 253 amp alternator. Although the alternator is one I got off R0CK Aut0 and i can't really be sure it's outputting those 253 amps.

Any help would be greatly appreciated.
 
#2 ·
Test the alternator for output and see what it's actually producing. Ive never had an issue with anything Ive purchased from Rock Auto over the years, but then again Ive also never bought anything listed under the Economy classification or any of the lesser priced items for whatever I was buying. I wouldnt think three batteries would be a necessity but it has been several years since Ive messed with any audio equipment. I also think you'd get a better feedback by posting this in the electrical section of the forum.
 
#3 ·
Thanks Zach....this is what I purchased from Rock

POWER SELECT / WPS 8292N253A {#8292253} Info
253 Amp Aftermarket upgrade

Not sure how to test the output other than to take it to a local eletrical shop and see what they tell me. At the moment the truck didn't even start. I left the lights on inside and i thought they shut off on their own. I guess this time they didnt? I went out to try it this morning and it didnt turn on. Left it on the charger and will try later. I will try to get this onto the correct subsection.

Thanks!
 
#5 ·
Duramax with Sound System needs 3 batteries? - RE-Posting in correct sub forum.

Hi all....

I have a 2004 GMC Sierra 2500HD. I have about a 2500-3000 watt sound system and I removed one of the acid batteries (standard battery) and replaced it with an XS Power D3400 AGM Battery. These are popular for sound systems as they are powerful enough to act like a capacitor as well.

The issue I am seeing is that if I am driving and listening to my system loud, I feel the transmission shifting harder/rougher. I go back and play the same song but lower it this time and drive again and the shifting is fine. No issues. So I am wondering if my 2 batteries is not enough or correct for the truck to function correctly? Not sure if anyone has seen this before. Do I need to add back my old battery and then possibly add the AGM battery as well on a bracket hidden somewhere under the truck? I have done the big three upgrade and have a 253 amp alternator. Although the alternator is one I got off R0CK Aut0 and i can't really be sure it's outputting those 253 amps.

Any help would be greatly appreciated.
 
#7 ·
Isn't there a safe conversion, X amount of Amperage means you can run Y amount of watts?

My roommate has 16- 10" Subs in his Yukon. He's running 3 alternators, with 4 batteries.

I'm assuming you've done the Big 3?
 
#9 ·
Yes, done the big 3. Running a 253 amp alternator by power master, purchased from rock auto. Not sure how good it really is. I am running 2 8 inch sundown audio subs, powered by an execution audio 1500watts rms amp, it does over 2000 watts though rms. Then I have a CT Sounds 125.4 to run my components. This does closer to 150-200 watts x 4 because its rms output is rated at 12.8 volts rather than 14.4 v. So when the truck is on, the output goes higher. This totals about 2500-3000 watts rms.
 
#8 ·
I "think" the battery/alternator tester at an auto parts store will give you a decent idea of what the output amperage is. So if you have an Autozone or Oreillys near by, once you get the truck started you could run by the parts store and have them test it for you. IIRC to test the batteries you have to disconnect one to test the other and vice versa. But for the alternator, I think you can leave both batteries hooked up and it wont effect the testing. Ive never had to run multiple batteries or excessively higher amperage alternators on anything so when it comes down to what you really need to keep up with your audio stuff I cant help there. Most Ive ever had in one vehicle was about 1400w ish.
 
#10 · (Edited)
You should replace both batteries at the same time and use two batteries that are the same unless you are running an isolator. For the dmax, it needs both batteries to start, so thats not a great idea...

Replace both batteries with some deep cycle batteries in the area of 1000CCA or beeter (each). Make sure you have at least 2ga, but preferrably 0ga cables going directly from the alternator to each positive terminal. And it goes without saying, but make sure you have a good size cable (0ga or 2/0ga) running to your power bar for the sound system and a solid ground to the chassis and body (multiple grounds from engine to chassis, engine to body and body to chassis are all as important as the batteries to chassis and body)

Very few alternators, but especially "economy or discount" ones will produce anything close to their rating. When they heat up, performance drops off, how much is what makes the difference between good, economy and top shelf alternators. Also what RPM is that 253 rated at? Does your engine spin it fast enough at 60mph on the highway to generate that? What about at idle? How much is it pulling down your batteries while you are stopped at a light?? Is that 253 still putting out even close to even 100 at idle while your system and the trucks various loads are pulling over 200 amps???

If you are serious about doing it right, throw a pair of deep cycle 1200CCA batteries in your truck, (I use a pair of 1500CCa odyssey) and look at a 270amp alternator from DC Power Engineering. It still puts out 180 amps at idle when hot, and makes the 270 just above 2500 rpm on a dmax... Or even better, get a pair of 250amp alternators. You could run the system full tilt with the truck idleing.
And then direct wire everything with 0ga wire including the cross over between the batteries.

Dont spend big bucks on a sound system and then skimp on a proper power system, it will affect far more than just the sound...
 
#11 ·
I removed one of the acid batteries (standard battery) and replaced it with an XS Power D3400 AGM Battery.
That's most likely your issue...you need 2 batteries with equal output. Your truck is acting like one battery is starting to go dead.
 
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