Do I need an additional battery? I already have 2 Something isn't adding up?


1000101

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I have a 2015 Silverado 2500 with a beefed up power system (at least I thought).

My Voltage starts at ~14.7V and when I bump it gets all they way down to ~12.4.

YES it recovers pretty good.. but I shouldn't be breaking under 13V PERIOD !

What's your thoughts here...? I'll list the basic components of my setup...below:
(I can provide a detailed schematic if needed).

1. 320 AMP Iraggi Alternator w/Big 3 (Actually Big 4). ALL GROUNDS CHECK 3x

2. 4000W RMS Memphis Amp (Running at 2000 W RMS at 2 Ohms)

3. ~500W RMS Memphis Mojo Amp (Running Mids/Highs).

4. 1 Memphis Mojo 12'' 1500 RMS 3000 Max

5. 2 (Yes Two) Yellowtop Optima AGM D34/78 (750 CCA 55Ah = 110Ah).

6. ALL WIRES are GP Audio 0 Gauge wires.

I checked for clipping and I'm not clipping. I have the GAINS on the 4k Amp ALL THE WAY DOWN. Overall everything sounds ok, I just get such a large voltage drop and EASILY.

The only thing I can think is that I need to increase the (aH) by adding an additional battery. OR Maybe I'm having a PCM issue (with these newer vehicles) the PCM Module | US Alternators PCM http://www.usalternators.com/gm-pcm/ may be my resolution?

The PROBLEM is that the alternator should not even remotely struggle or have to even use the batteries period. Especially since I have my gains all the way down. (I checked 1x with a Clamp Meter and when at ~12.6V it was outputting 16-40A Max.) (Aka not struggling etc).

PLEASE HELP !!
 

hispls

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I'd be running more battery on that, and yellow top is NOT what they used to be. Obviously if you're charging fine not under load you need more something. Personally pre-lithium I'd be running 250AH of AGM on a 3K amp plus high output alternator. Sounds like you're maybe 100.
 

Coolhand20th

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Yellow top AGM's are bottom of the barrel batteries. Nothing is special about them anymore. Owned by johnson controls and they are selling because of the name nothing more. You can get the same kind of AGM anymore from johnson controls that cost less.

XS Power makes a really nice battery but you will pay for it. I am putting in a XS Power D6500 that is rated for 4K in the next couple of months but it is 370 dollars. I would do what hispls says. If I had more room I would be doing lithium in a heart beat.
 

Popwarhomie

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From what I just read the voltage is PCM controlled.
 
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Dafaseles

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From what I just read the voltage is PCM controlled.
I have a 2011 Silverado and from what I've read, 2006 and up all have a regulated voltage controller. Also, that RVC doesn't like it much when you ground to the frame. It doesn't get a good reading on if the batteries need to be charged when they need it. So my "big 3" has to be more like a big 2. I have a 1/0 gauge cable from the battery ground, going through the RVC "doughnut" grounded to the engine block, and everything else (secondary battery ground, amplifiers to a solid distribution block with 2 runs of 4/0) is ground straight to the alternator ground. If I'm not mistaken, it's called a closed loop circuit. I could be wrong on the name though.
When the truck first starts, or when it senses the battery needs recharging, it'll push the alternator to 15.3 ish. After it warms up, it'll drop down to 13.8 ish. But, at least on mine, if I keep the headlights on, it stays around 14.7 charging. It'll only charge the batteries to 80%-85%ish though to save on fuel and battery life.
The only way I've found to deal with the RVC is wire the system like I've stated, or get an externally regulated alternator and bypass the system completely.
Hope this helps.

P.s. those Optima batteries are only manufacturer rated at 72 AH a piece, and like previously stated, are not what they used to be.

One last thing, how many runs between the alternator and the battery do you have? And how many runs between batteries do you have? On that power, I personally would do 2 runs from alternator to battery, and 2 runs from battery to battery. If you haven't already. That will help aid with the speed the batteries recover at
 
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AnthonyO

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PCM
 
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1000101

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  • Thread Starter Thread Starter
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I have a 2011 Silverado and from what I've read, 2006 and up all have a regulated voltage controller. Also, that RVC doesn't like it much when you ground to the frame. It doesn't get a good reading on if the batteries need to be charged when they need it. So my "big 3" has to be more like a big 2. I have a 1/0 gauge cable from the battery ground, going through the RVC "doughnut" grounded to the engine block, and everything else (secondary battery ground, amplifiers to a solid distribution block with 2 runs of 4/0) is ground straight to the alternator ground. If I'm not mistaken, it's called a closed loop circuit. I could be wrong on the name though.
When the truck first starts, or when it senses the battery needs recharging, it'll push the alternator to 15.3 ish. After it warms up, it'll drop down to 13.8 ish. But, at least on mine, if I keep the headlights on, it stays around 14.7 charging. It'll only charge the batteries to 80%-85%ish though to save on fuel and battery life.
The only way I've found to deal with the RVC is wire the system like I've stated, or get an externally regulated alternator and bypass the system completely.
Hope this helps.

P.s. those Optima batteries are only manufacturer rated at 72 AH a piece, and like previously stated, are not what they used to be.

One last thing, how many runs between the alternator and the battery do you have? And how many runs between batteries do you have? On that power, I personally would do 2 runs from alternator to battery, and 2 runs from battery to battery. If you haven't already. That will help aid with the speed the batteries recover at
From what I just read the voltage is PCM controlled.
Yellow top AGM's are bottom of the barrel batteries. Nothing is special about them anymore. Owned by johnson controls and they are selling because of the name nothing more. You can get the same kind of AGM anymore from johnson controls that cost less.

XS Power makes a really nice battery but you will pay for it. I am putting in a XS Power D6500 that is rated for 4K in the next couple of months but it is 370 dollars. I would do what hispls says. If I had more room I would be doing lithium in a heart beat.
I'd be running more battery on that, and yellow top is NOT what they used to be. Obviously if you're charging fine not under load you need more something. Personally pre-lithium I'd be running 250AH of AGM on a 3K amp plus high output alternator. Sounds like you're maybe 100.
Sorry for the late reply's , but I think I'm close to a resolution (I was on DIYMobilAudio.com) with the same question. I got a lot of responses on there too. (And Thank you all for still assisting... I'm not resolved just yet.. still more testing to do).

But in a Nut shell...

I may need more Amp Hours (aka better batteries). But may also need a PCM regulator.

Also, Dafasles, The setup you're talking about with the "Current Sensor Loop" was what had me confused in the very beginning.... Everyone told me I had this .. INCLUDING LITERALLY LIKE 5-7 Installation Shops. ALL for me to find out that they were WRONG. The Chevrolet/GMC 1500's have the setup you mention... but 2500/3500 DO NOT. (I have a 2500).

Also if anyone is interested in the topic Dafasles mentioned, (I SUGGEST YOU READ ON IT IF YOU SO OWN A SILVERADO 1500), because it WILL affect your setup PERIOD. Please visit my thread at this link.. I compiled a lot of links/videos and a fellow poster shared a really good video on GM's RVC / SRVC PCM Controls.

Here's the link: https://www.caraudio.com/threads/do-i-need-an-additional-battery-i-already-have-2-something-isnt-adding-up.608427/


Overall thank you all so far.. I'll give updates soon
 
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Bobbytwonames

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I have the same problem in my Dodge with a 320 amp alternator, big 3, and an AGM battery. I'll drop into the high 11's on bass heavy songs after 30 seconds. I'm adding a bank of Lishen lithium to hopefully solve the voltage drop issue. I only ran 5 cells. Some people run six but not necessary.

20210629_154445.jpg
20210629_154425.jpg
 
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1000101

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  • Thread Starter Thread Starter
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I have the same problem in my Dodge with a 320 amp alternator, big 3, and an AGM battery. I'll drop into the high 11's on bass heavy songs after 30 seconds. I'm adding a bank of Lishen lithium to hopefully solve the voltage drop issue. I only ran 5 cells. Some people run six but not necessary.

View attachment 30248View attachment 30249
I'd like to hear your results from this.. please keep us updated
 

Bobbytwonames

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I'd like to hear your results from this.. please keep us updated
I've currently got and AGM and a 320 Mechman. My sub amp is a Sundown SIA3500 on 4-8's. But I'm still dropping into the 11's. How in the hell is 320 amp alternator and an AGM not enough for 4-8's? We are about to see if the one bank of lithium solves the problem.
 

Dafaseles

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Nov 12, 2020
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510
Sorry for the late reply's , but I think I'm close to a resolution (I was on DIYMobilAudio.com) with the same question. I got a lot of responses on there too. (And Thank you all for still assisting... I'm not resolved just yet.. still more testing to do).

But in a Nut shell...

I may need more Amp Hours (aka better batteries). But may also need a PCM regulator.

Also, Dafasles, The setup you're talking about with the "Current Sensor Loop" was what had me confused in the very beginning.... Everyone told me I had this .. INCLUDING LITERALLY LIKE 5-7 Installation Shops. ALL for me to find out that they were WRONG. The Chevrolet/GMC 1500's have the setup you mention... but 2500/3500 DO NOT. (I have a 2500).

Also if anyone is interested in the topic Dafasles mentioned, (I SUGGEST YOU READ ON IT IF YOU SO OWN A SILVERADO 1500), because it WILL affect your setup PERIOD. Please visit my thread at this link.. I compiled a lot of links/videos and a fellow poster shared a really good video on GM's RVC / SRVC PCM Controls.

Here's the link: https://www.caraudio.com/threads/do-i-need-an-additional-battery-i-already-have-2-something-isnt-adding-up.608427/


Overall thank you all so far.. I'll give updates soon
I didn't even see it was a 2500. Sorry. I must have just glanced over that (even though it's in the first line lol).
Well, I used to run 4 JX1000.1's and 2 JX400.4's on a mechman 370 and 160 AH of Stinger AGM (2 SPP1500DC's) with no voltage issues. So, if I had to guess, I'm saying it's those Optima batteries just not up for the challenge.
But I've reread your initial post a couple times and it doesn't say how many runs you have between your alternator and your batteries and how many you have between your batteries. (If it does, I'm sorry). If you're only doing 1 run off 1/0 cable between each, it could just be that not enough current is getting to your batteries efficiently or fast enough to keep those batteries fed nicely.
 
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hispls

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How in the hell is 320 amp alternator and an AGM not enough for 4-8's?
The piston diameter of the woofers isn't what determines how much power your amp needs to draw. Your "320A" alternator will very probably never output 320A under real world conditions in a vehicle and AGM is a very poor discharge curve beyond .5C or wherever they rate.

Oh, and if you're only running 5S battery bank you had better hope you never charge over 14.4
 
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Kickstand

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Oh, and if you're only running 5S battery bank you had better hope you never charge over 14.4
Why?
I'm not trying to be a dick
I am however trying to learn as much as I can about lithium as I hope it can solve some problems for me in the not so distant future.
 

hispls

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Why?
I'm not trying to be a dick
I am however trying to learn as much as I can about lithium as I hope it can solve some problems for me in the not so distant future.
Because maximum charge voltage for those is 2.9V and 2.9X5 = 14.5
 

Bobbytwonames

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The piston diameter of the woofers isn't what determines how much power your amp needs to draw. Your "320A" alternator will very probably never output 320A under real world conditions in a vehicle and AGM is a very poor discharge curve beyond .5C or wherever they rate.

Oh, and if you're only running 5S battery bank you had better hope you never charge over 14.4
My truck computer stops the alternator at 14.4.
 

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