KiLaHuRtZ

I've been speaking with Josh via email the past few days and am going to try a few things just to be 100% sure it is the computer bucking the voltage down. I will reply back with the tests I did and the results of those tests once they are completed. Although, Josh did tell me something interesting and I wanted to see if anyone else has heard of this. He said this is not related to my current issue, but he said because I will be wiring the amplifies directly to the alternator that over time in the future it would burn the positive stud off of the alternator. Mind you I have one connection off of the alternator going towards the batteries and another off of the alternator going towards the amplifiers. Josh confirmed with me on this, but the only reason I see the positive stud being burned off was if there was a resistance over that connection causing a voltage drop. I am using 100% copper wire (OFC) and 100% copper lugs. I don't think this would be an issue because there is no resistance (or very very small, too small to measure) going over it. I did it this way since the alternator is the primary source of power when the engine is on. However, Josh disagreed in this respect and said the alternator just maintains and replenishes the batteries. I am torn on this one, because I want to believe Josh as he works for Mechman and should know. But, it goes against basic knowledge on how the alternator/battery system works. Now before anyone says it, I know that if the stud on the alternator gets corroded then, obviously, I would have bigger problems and it could indeed burn off. And before anyone mentions ripple current, basic electronics dictates that regardless of where the battery is in the circuit, as long as it is parallel to the ripple producer (the alternator in this case), it will still filter the ripple current. So, with all that said, I am curious what the veterans and the community have to input on how I will have the amplifiers wired to the alternator and Josh's words of wisdom from Mechman? Or am I just worrying about something that is so rare to happen that I shouldn't worry at all? I will only be running about 2800-3000 watts RMS total, nothing crazy.

Thanks!

Here are a couple of photos of the setup. I will be posting all my photos later in the Member Builds forum once it is all done. https://goo.gl/photos/JA31niC46Es4HoCE6

I ran the RVC thing by Richard, from Mechman, and he said he spoke to Josh, also from Mechman, after our call yesterday about it. Richard said that Josh has an '06 and it also does some of the same stuff. The RVC trying to be he most efficient as possible about it, since I have no real load on it and the batteries are fresh. Richard instructed me to let them know how it performs once I get some load on it. So with that said, I will report back with my findings once I get my stuff installed and wired up.

I found this and i think it answers all my questions. http://acdelcotechconnect.com/pdf/imtn_V12I305.pdf I guess this new regulated voltage control system (RVC) is pretty elaborate. From what I know and what I learned, it seems the computer does not disable the alternator but rather steps the charge voltage down in increments (PWM signal) based on various input data it gathers (like an intellicharger). After reading it, I believe with the Mechman alternator spinning at a higher RPM than stock, the computer is kicking down the voltage earlier at around 3000 RPM because, well, I don't need that additional output yet! So it's reading my batteries state and since they are new and not really loaded yet, it is keeping them from being overcharged. I can only assume that once I put some amp load on it, and some big current is moving, I am willing to bet the computer will keep the alternator voltage up more at 3000 RPM. So I'm fairly certain the symptom I am seeing is by design.

This has some sense to it. I only noticed this when accelerating to merge into traffic. The alternator performs fine at idle speed of 500 RPM and cruzing speed of 1500-2500 RPM. So it really is not that big of a deal for me. I just wanted to be sure that it was supposed to behave like this and that I did not have a bad alternator or did something wrong in my setup. So to make sure I understand, this would be my truck's computer telling the alternator to "cutout" to: 1) protect the alternator, 2) make more HP available during acceleration? That being said, I guess I would need to keep an eye on the RPM's when I pull anything with my truck. I think I am going to drive it for a while and see if I accumulate any belt dust before buying another shorter belt. Or wait to put some load on it and see if it slips, etc. Richard, from Mechman, also said the Gates Micro-V was fine, however once I nail down the length I need I will be upgrading to the Gates Green Stripe.

Just spoke on the phone with Richard from Mechman. He recommends going with the shorter belt and said the tensioner being almost maxed out shouldn't be an issue. I should note that the batteries are wired together and then a single ground cable goes through the hall effect load sensor to the alternator negative. I also have a ground cable going from the alternator negative to chassis ground. I did this because it was how things were wired up stock, only difference was in the stock wiring the chassis ground was from engine block to the chassis and the battery ground was from engine block through the load sensor to battery; which for my wiring I used the negative alternator post instead of going through the engine block. Anyway, Richard also mentioned that the additional ground from the alternator to the chassis might be causing the problem. I will try that next after the shorter belt, however after getting off the phone with him, It dawned on me that the ground from the alternator to the chassis should not be a problem as my understanding of the hall effect load sensor was to detect current flow to and from the alternator to the battery. If enough current is flowing from the battery to/through the alternator and the voltage is going down, then the computer should excite the alternator and start charging. If it is the other way around, then the alternator should be charging until the voltage is high again. So my negative wiring goes as follows... Battery 1 -to- Battery 2 Battery 2 -to- Alternator (Through load sensor.) Alternator -to- Engine Block Engine Block -to- Chassis I don't see how that would cause a problem at high RPM. Anyway, I will report back my findings.

I replaced the tensioner when I installed the new alternator. It's brand new as well.

Also the batteries, although Duralast AGM's, are both brand new as well.

Sent the following to Mechman via their online form, but I figured I would post here to see if anyone else has any insight on this for me in the mean time while waiting for their response. "Hello, I purchased one of your alternators, via Sonic Electronix, for my 2008 Chevy Silverado. It has the 5.3L (VIN-J) and the alternator model is the 270A 8302270. I wired it with all 1/0 OFC cable, ensured the ground from the alternator to the battery runs through the Hall Effect sensor, used a 3/8” shorter belt (Gates) and replaced the tensioner for a new one (Gates). All works great except one thing, when the engine gets to about 3000-3500 RPM the voltage drops to battery voltage, then once back to idle the voltage comes back up. I'm not sure if this is by design or if there is some belt slippage at high RPM. If it is the latter, I cannot tell since it is a new install and I see no indication of belt dust yet. I wanted to get your input before I start going out buying anything. I eventually am going to order Gates Green Strip belts since I cannot get them locally, but I want to be sure of the length before I do. Right now, I have brand new Gate Micro-V belts installed since I can get those locally. The stock belt is 94" (K060935). Right now I have the 93-5/8" (K060930) installed, but the 93" (K060923) will fit, however with the 93" installed the tensioner is almost maxed, unsure if that is a factor or not. If you think I need a shorter belt, I will go out and purchase the 93" and if that solves my problem, I will be ordering the 93" Green Strip version (K060923HD). Thanks in advance and I hope to hear from you soon so I can resolve this." I should also mention I did try the 93" but never ran it with it due to the tensioner being almost maxed, so I returned it for the currently installed 93-5/8". I'm doing a new build to, so other than stock components, there are no aftermarket devices (amps, etc.) putting any additional load on the alternator other than a second battery.