High Output Alternator or 2nd Battery?

[John Doe]

Need advice on what would be the better route. Got a 2019 GMC Sierra Denali. Got a 4K Korean on a DB drive WDX G5, and about 8 mids, & 4 tweeters running off a DB drive A7 125.4. Issue is sub cutting out couple days after getting it back when I turn the Volume on the HU up(OEM headunit running a JL Fix 86). If it’s due to lack of electrical support would I be better off getting a HO Alt even though the max I can get is a 250A, or a lithium? I currently have 2 Duracell 80AH AGMs.

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[audiobaun 5,000+ posts]

Have you done the BIG3 Yet??

 

[John Doe]

Have you done the BIG3 Yet??

Yes. Done the big 3. Mind you I had a shop do it. Good people. Gonna go back this Friday and have them double check and trouble shoot just in case. But I was already planning on going a little bigger with the electrical anyway.

 

[audiobaun 5,000+ posts]

Yes. Done the big 3. Mind you I had a shop do it. Good people. Gonna go back this Friday and have them double check and trouble shoot just in case. But I was already planning on going a little bigger with the electrical anyway.

An HO Alt will deff help the the supply for the demand. My 14 HD I think has like a 140?/ I am about to put a 250 on it. Its for a 5k inverter and a Tommlift I use in that truck and I have another 1000CA AGM that needs go in. An HO alt is always a plus, along with the Big3

 

[audiobaun 5,000+ posts]

Yes. Done the big 3. Mind you I had a shop do it. Good people. Gonna go back this Friday and have them double check and trouble shoot just in case. But I was already planning on going a little bigger with the electrical anyway.

0ga OFC on the Big3?

 

[John Doe]

0ga OFC on the Big3?

Yes sir.

 

[metalheadjoe 10+ year member]

I'd go battery before alternator.

 

[audiobaun 5,000+ posts]

I'd go battery before alternator.

I think he said he already had Two AGMs already? A third would be almost the same price as the 250 amp alt,after installed with no other wiring or cables involved, and would be more beneficial and not wearing out the existing alternator to keep up with the demand. Thats from my experiences hands on

 

[John Doe]

I'd go battery before alternator.

How do I bypass or work around the smart charging system? Shits making my voltage go haywire and that seems to possibly be the problem.

 

[metalheadjoe 10+ year member]

I think he said he already had Two AGMs already? A third would be almost the same price as the 250 amp alt,after installed with no other wiring or cables involved, and would be more beneficial and not wearing out the existing alternator to keep up with the demand. Thats from my experiences hands on

Battery power is instant, whereas alternator power has a delay. Upgrade the alternator if it doesn't keep your batteries charged.

Not saying you are wrong, but my experience is different than yours.

 

[John Doe]

I think he said he already had Two AGMs already? A third would be almost the same price as the 250 amp alt,after installed with no other wiring or cables involved, and would be more beneficial and not wearing out the existing alternator to keep up with the demand. Thats from my experiences hands on

Will a HO alt help bypass the smart charging system making my voltage go all over the place? I think it dropping to 12s was making my amp go into protect mode.

 

[audiobaun 5,000+ posts]

Will a HO alt help bypass the smart charging system making my voltage go all over the place? I think it dropping to 12s was making my amp go into protect mode.

It shouldnt. You can have the truck put on Diagnostic to relearn/program the Voltage.But shouldnt need to. You could very well be correct with the Amp going into Protect in the low 12s. Some amps ive experienced with in the 20+ years in this hobby Ive seen older ones that will not up until the low 10s upper 9s, and some newer ones that state 12.5-16v I have seen them go down to low 11s some more sensitive to 12.5/4 even 12.6 and up to 15.8. Its good that its working for you. Its saving your Amp from roasting for sure. Its doing its job in Protective Mode

 

[audiobaun 5,000+ posts]

Battery power is instant, whereas alternator power has a delay. Upgrade the alternator if it doesn't keep your batteries charged.

Not saying you are wrong, but my experience is different than yours.

Thanks.. I have ran 6 batteries on a 255, and later upgraded to a 320

 

[metalheadjoe 10+ year member]

Thanks.. I have ran 6 batteries on a 255, and later upgraded to a 320

I ran a single battery on a 320a, and adding lithium battery solved my headlight dimming. So we each have our reasoning. Not trying to argue.

OP: i don't know how to get around "smart" electronics. One more reason for me to avoid new vehicles.

 

[HardofWhoring]

An alternator recharges a battery. The older alternators would work at full charge and dissipate the excess to keep it in range. If your alternator wasn't producing enough, you would see your voltage steadily dropping. It might just be going to slow to notice, but I would expect it to take at least a half hour to an hour on full to notice if the alternator is not keeping up.
I know your vehicle has the computer controlled alternator, and I think you do need to upgrade your alt, especially if you fix the upcoming problem.

A battery is going to give you a larger storage bank to pull from. This is on the same principle but you are starting with more stored energy. If your alternator is not keeping up, you will see it drop, it will just take longer to empty. The larger storage bank is really only best if you plan to use a lot of that energy when it WONT be recharged, (because the engine is off). If you use it for work, or outdoors, or need the energy from the vehicle for an extended period of time, then a larger battery is better.

I think you will need to upgrade the alternator when you fix the first problem which is: 0ga wire is nowhere near big enough for a 4K watt amp. 4k watt amp /12v = 333 amps. Add that to your nearly 100 amp vehicle with everything else, and Your Big 3 and your amps main wiring should probably be at least 3/0, and I would probably go 4/0 just because. If you are cranking up a 4k watt amp and have 0ga wire, you are pulling amperage out of your vehicle's electrical system.

It should be the first thing, but I would start with redoing the big 3 you just had done, with larger wire, (My suggestion is 4/0, I've had good results with Knuconceptz, or whatever you choose). Your amp's power and ground wire should be at least 3/0.
After that you should be pulling much more amperage, and If that's the largest alternator you can get, get that one. Ideally an alternator that can produce the amperage of your entire electrical (lets say 333 + 100) would be enough to keep your batteries from draining. It might be worth looking up to see if dual alternators at that size is an option. If someone made em for the previous model it might fit, or you might help show them there is a demand for em. If you have multiple options at that size, you want to know two things about that alternator: what is it's amperage output at (or near) idle, and what rpm is needed to produce max output. Any quality manufacturer can give you at least those numbers, and the better ones can give you a curve to that exact alt when they test it. Compare max output to what RPMs you are usually driving at, and see if you're going to be able to charge.
If after that there is currently not yet a larger option, THEN a battery with a larger starting bank would be the third thing to upgrade. This would probably be somewhere in the range of listening to it at full volume for more than an hour.