Bypassing battery?

[2023 LTZ]

I’m still looking to remedy this voltage fluctuation. Big 5-7, ho alternator, flooded mtx 34, theoretical 1900rms fused w cap. Not the best looking install bc of additional additions but it’s clean and functional.
I removed 4/0 from alt and ground to chassis. This reduced the voltage to what I’d consider normal. +\-13.5-15.1.
If I bypass the battery w my fused feed for the amps directly to the alternator will this change it’s performance? I’ve ordered a replacement voltage sensor which is a key component in voltage regulation and intend to have it on the replacement 4/0 chassis ground by the headlight. The sensor originally and currently encompasses the starter and alternator ground. Previously having the 4/0 to the chassis and sensor in oe location I believed too much ground was occurring outside the sensor loop causing my perceived overcharging. So if I hook the amp lead directly to alternator and ground to chassis w sensor maybe I’ll overcome the fluctuations.
Now reading this it seems like a dumb idea. I’ll just ground to chassis w sensor and try that.

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[Dafaseles]

I'm sure you heard this before, but incase you haven't....
What I did was purchase a HO alternator with the old 4 pin plug (2005 and older I think) then ran the wire from the pin to a switched 12v source to tell the alternator to start working. GM hasn't changed their mounting setup since 1986 i believe, so they fit right in. I get a solid 15v at startup, then 14.7 after warmup. Swinging from the low 13's to a little above 15v is normal when not bypassing the RVC sensor, and really, unless your competing, it's really not going to effect your listening too much. Unfortunately, to remedy the voltage fluctuation, the only solution I know of is to bypass the RVC sensor, and to do that, you'd have to purchase an alternator with the 4 pin plug.
I don't know if this helps you, but if rather say something and not have to, then not say something and should have. I went through the same thing.

 

[2023 LTZ]

Hey I appreciate this insight. The folks on a body specific forum have circled around this issue when I bring it up. Meaning it’s my alternator or battery or one time they had a similar issue that was not the same. You have put your finger exactly on my issue and offered a solution.. Do you believe this is a part of my battery killing and possibly agree w my deduction thats it’s the periodic huge draw on the system which excites the alternator to do it’s job there by introducing a lot of voltage which essentially just transfers through the battery? If this fluctuation is normal it has to be the replacement of lost/dedicated voltage to my system.

 

[Dafaseles]

Honestly, your truck would be behaving like this without the system as well. That's how the voltage regulation system is designed. When it needs to charge, and upon initial startup, it'll push 15.3 ish and after warmup and when not needed, to "save fuel" it'll drop to the low 13's.

I've read bypassing the RVC ring (grounding something straight to the engine block without first passing through the ring) can confuse the system, and cause minor/ major electrical gremlins within the system, though I didn't ever test this myself.

Grounding for us (unless you bypass the 2 pin plug as I have done) requires us to ground everything to the negative battery terminal, then from the battery terminal, through the ring, then to the engine block. My last system, before I bypassed the system, I got the stock cable, and a 1/0 awg cable through that ring for grounding. I didn't even notice the voltage fluctuations. Really the only reason I bypassed the system now is because I'm planning on running lithium.

 

[hispls 5,000+ posts]

If I bypass the battery w my fused feed for the amps directly to the alternator will this change it’s performance?

The only sure "fix" I can think of is to add a second alternator and battery for just your audio/accessories. I too believe this variation you see is by design of your vehicle. It is possible that just buying an internally regulated aftermarket alternator or otherwise bypassing the ECU to externally regulate your alternator will sort you out but I wouldn't begin to try to guess if your ECU might get angry if it keeps telling the car to charge at one voltage but keeps reading something different.

IMO your best bet is to just buy amplifier(s) that are known to function without issue within the 13.0 to 15.2V range. If you leave a couple hundred watts on the table for not having 15V all the time it will likely be inaudible and I don't believe any modern amplifier is going to give you trouble, fail, or protect if you can keep it above 12V and below 15.5V. There's some that can get into trouble above 15.0V but only in extreme (competition type) applications. I don't believe you're going to have any issues for just a normal system that you use for playing music.

 

[2023 LTZ]

Thank you
These amps are tolerant to 16v
It seems weird that w headlights, fan on medium and volume off it has occasionally stayed at 15v. I have a couple batteries but am hesitant to buy a decent isolator to find it didn’t change. Maybe the audio system is irrelevant to charging or doesn’t play a role in this. The oe alternator did the same thing. Maybe I’ve created in my mind this is a problem. The battery or cel have never come on.
I appreciate the insight enthusiasts.

 

[2023 LTZ]

Oddly enough after I disconnect then reconnect the battery it misbehaves more frequently. I can trick it by turning on rear defrost, seat heat on high, high beams and auxiliary lights while parked and it seems to snap back to under 15 and play nice.

 

[hispls 5,000+ posts]

Maybe the audio system is irrelevant to charging or doesn’t play a role in this.

This is because the issue comes from the car's ECU which is trying to be "smart" about how high to charge based on several variables to try to squeeze a tiny bit more fuel efficiency out of the car by not loading down when it isn't necessary. I'd be willing to bet the exact formula of what it measures and when it decides to charge where is a mystery to everybody besides the engineers who figured out how to save 0.1MPG or whatever.

Safe to say outside temperature, current load draw and possibly some sort of average engine RPM would come into play but possibly also something that considers battery health somehow. That's the first things I'd be looking to monitor if I'm trying to figure out a charging system intended to fluctuate.

 

[2023 LTZ]

Ok
While my hair grows back should I consider utilizing a large deep cycle battery and an isolator? The theory of that being to protect the passing of considerable voltage through my start battery?
At idle listening to say “tech nine- crazy” voltage dips to 11 briefly while the charge system which monitors the negative side, activates and makes up for the difference. I believe is the cause of my batteries failure. I’d it’d help I guess I’m in but between the jy2k farad, isolator and retail of this monster deep cycle I may as well have bought a couple batteries.
1st world problems..

 

[HardofWhoring]

11volts is normal for those 2005+ alternators. The older style with the internal regulators charged at full, constantly, and dissipated the excess. The new style is trying to only charge as needed so there is less drag on the belt.

I'm sure it's more than .1 for this. The GM/Chevy full size, (since the start of the Gen III)/ over the last 20 years has increased power by about 15%, and doubled highway mpg for the same size engine.

 

[hispls 5,000+ posts]

Ok
While my hair grows back should I consider utilizing a large deep cycle battery and an isolator? The theory of that being to protect the passing of considerable voltage through my start battery?
At idle listening to say “tech nine- crazy” voltage dips to 11 briefly while the charge system which monitors the negative side, activates and makes up for the difference. I believe is the cause of my batteries failure. I’d it’d help I guess I’m in but between the jy2k farad, isolator and retail of this monster deep cycle I may as well have bought a couple batteries.
1st world problems..

I'd say additional battery yes, isolator, no. By my estimation there are very few car audio applications where an isolator would be appropriate. Get the biggest parts store "premium" branded AGM battery you can bear the size and weight of and chose the one with the longest warranty. Pep boys used to sell Bosch brand with 3 year warranty which was pretty nice. Before getting into lithium (I wouldn't recommend lithium for 2KW audio system) I used to do that and parts store batteries are always no-******** exchange if you kill them within warranty. Drive to the local parts store and the kid behind the counter checks your receipt and hands you a new one, easy peasy compared to the cost/hassle of having to return one to some boutique battery brand on the other side of the country.

 

[2023 LTZ]

I appreciate your thoughts. What of the battery manufacturer recommendation not to mix types of batteries? Is that not a concern?
I live in the same town as the interstate North American distribution center and I’m black listed there, well at all interstate retailers bc they believe something w my car is responsible for the killing of these batteries. I spoke with a local installer who had a very similar vehicle in w stock alternator, no cap and a second battery in place but that vehicle didn’t go below 13.5v. The proprietor said that persons system was 3k where mine is 2. His recommendation was have the auto parts store check the ho alternator bc in his experience the alternator should instantaneously respond to this demand placed on the system. I’m inclined to disagree with that.
So, having two batteries of different types is ok and they don’t feed off each other?