2007LTZ

Hey fellow members. I'm new to the forums but not new to my Tahoe. I'm finally starting to upgrade things and have a question about the RVC (Regulated Voltage Control) on the ground. From my research there is a sensor around the ground wiring coming from the engine ground up the battery.

Now I just installed 2 brand new AGM batteries that are oversized. I have a Mechman 370 amp alternator I am about to install once I can get this figured out I would like for the batteries to get a continuous 14.5-15.0 volts. Now I am going to do the Big 3 of course, with 0 gauge wire. Should I keep the sensor, bypass the sensor, or install the 0 gauge ground wire through the sensor? I want that 14.5 volts but is there any added benefit from letting the BCM control the charging system? Can I just run a bigger wire through the sensor to have it be more stable?

I know I can enable tow/haul mode to enter into "Charge Mode" at idle but I want to drive and have it charge. I also understand charging the batteries while driving will lower my MPG.

I greatly appreciate and replies and I look forward to being a member of this forum and helping out others based on my 12 years of owing a Tahoe!

mountainmanjoe

It's a bad idea to have your alternator crank out 14.5 - 15.0 V all the time. It's wasted energy that will just be turned into heat in the battery, cooking it, and reducing its usable life. Not to mention being harder on your alternator and fuel economy. Even AGM batteries are float charged at 13.5V. Read the charging instructions on your battery datasheet.

RVC is intended to adapt charging and loads to changing situations to prolong the life of the electrical system so why mess with it? Do not bypass the sensor. That will just confuse the system, leading to unpredictable results, and maybe even set off the trouble light. Running a fatter ground cable through the sensor will make absolutely no difference.

Do not do "Big 3". What for? The manufacturer has sized the wires appropriately for your vehicle. Just make sure the existing ones are clean and tight. Often when people do "Big 3", they are bypassing fusible links making the whole thing a bigger fire hazard.

Tow haul mode is for towing. It changes the shifting. Where did you hear it affects charging?

I don't understand. Does your battery not usually charge while you drive?

2007LTZ

Tow haul mode entered charge mode because people were complaining their trailer batteries were dying while driving so they made it where the Tow haul mode entered charging mode.
https://www.silveradosierra.com/towi...20or%20trailer.

I can also confirm that Tow/Haul mode does enable charging mode since when I enable it I do see more voltage on a voltmeter.

Alternators have been putting out 14.5v since this RVC technology and everything has been perfectly fine. I have a lot of accessories onboard and will use every tenth of a volt and turn it into usable power.

Running a bigger wire through the sensor when you change all other wiring size does in fact level out the charge. I did some research and found a youtube video in which he just did the Big 3, not even a bigger alternator and explained how when your vehicle enters charging mode it won't charge very fast and rapidly. It keeps the output a higher voltage and doesn't push a harsh charge on the battery so quickly.

​​​​​

73shark

2007LTZ, welcome to the forum. I had both a 2007 LTZ and a 2010 LTZ and was initially dismayed when I saw the voltmeter consistently below 13 1/2 volts. But then I did little study and found out about the way they were supposedly achieving improved mileage was by cutting the alternator output when it wasn't needed.

I do recall that the RV I owned had two AGM batteries that required a special four phase charging profile. Not sure what happens if you just use a regular alternator that supplies a constant voltage. But you seem to be fairly knowledgeable about that so you'll probably figure it out.

2007LTZ

Thank you for your kind words! I appreciate it.

mountainmanjoe

Thanks for the link. I was able to locate this GM bulletin #07-06-03-009
https://static.nhtsa.gov/odi/tsbs/20...39409-9999.pdf
Since the current sensor is on the primary starting battery, the computer cannot sense the state of charge of the trailer battery , and it wasn't being properly charged. It doesn't apply to you.

I don't understand what "leveling out the charge" means. Charging is supposed to have different levels. The guy in the video is a goof. The sensor simply measures current through a wire. It doesn't care if it's a 2 AWG wire or 1/0 AWG wire.

This doesn't make any sense. Higher voltage = more current.

It doesn't take long to fully charge a battery after starting the engine. Put a multimeter on it when you get home. If your battery voltage is at least 12.7V then there's nothing to worry about.