Voltage gauge normal reading

[bdbake01]

Right now my main 2/0 ground is going back to the first battery I was told by GM that if it was going to the trucks frame it would bypass the voltage computer that controls the altanator. They said it was on the negative ground of the main battery lead.

Gotcha. To be fair, I haven't chased the neg cable. While possible that GM placed an ammeter in the neg lead, I find it questionable. That said, it would work.

 

One concern I would have with connecting the two neg posts together is that now ALL of the current produced by both batteries now has to share the factory neg lead, which is now most likely undersized. In a perfect, albeit unlikely scenario, this could cause a fire.

[sunryz76]

Hello, all. I believe I may have a more serious issue. I very rarely see my gauge in any position but either full charge or off. As a result, I believe it is causing the same issues people are seeing with regards to vibration and transmission shift point and firmness. As they're all electronically controlled, they are all related. I have nearly had my pickup die as I pulled out into a fairly heavy traffic situation, and sure enough, once I was out of danger of being t-boned by a gravel truck, my gauge was sitting almost level with the low "acceptable" needle. When it's on the low level, the truck idles rough, the transmission is sluggish and slippery, shifts too soon or too late, and vibrates more at highway speed than it does when I'm rolling along at the full charge. This is my very first new anything, but I've worked on electronics for the US Navy and several other civilian contractors; I am no engineer. But I can say that in my experience, a voltage shift of this nature would explain a lot. I personally would prefer the voltage "shifting" would be eliminated, charge my battery at a regulated 13.8 volts level, and let my truck run like it should. I am willing to replace a battery a year sooner to have consistent performance. I seriously doubt the load from the alternator is costing much in the way of fuel efficiency, but again, I am no engineer.

 

I also would like to ask if anyone else's truck gets so low when sitting in the driveway idling that their headlights and dash lights dim just because you press the brake pedal? I have a factory stock 79 Z-28 that idles at 750 rpm that doesn't do that, and neither does my 04 Jeep Rubicon. I had a 1966 Dodge Charger that did though. We won't talk about how big and pretty that pile of crap was.....

 

Anyway, before I drop my truck off at the dealership with all this info, I wanted to ask finer minds than mine. I'm sure they'll have it in their possession for at least one payment period scratching their heads rather than listening to what a "stupid customer" said..... lol!! (Jk of course; not all techs are arrogant in this fashion).

[sunryz76]

 

One condition; I should add it doesn't matter what accessories, lights, chargers, climate settings, etc. I use. It's either full charge or no charge (assumed, of course, but never a middle ground)

[sunryz76]

any help is appreciated. Thanks!!

[silveradosid]

i believe the low end voltage is 12.8, which is why even with upgrade to the headlights they suck at night when the voltage drops this low. my truck does this even with the blower on high, which is why i have hid headlights

[bakerk2]

Kind of an old thread but I just traded my '15 LT for a '17 Z71. I noticed the Volt gauge was reading over 14 and my radar detector voltage was pinging 16.1 at times causing it to shut off. Through the break in period (first 500) this was constantly the case. I'd start up the truck at 15.3-15.5 and it would rise to 16 eventually. No lights no warning messages. I hit 500 miles and key cycled the truck but the volts didn't change. At 512 miles I key cycled again and the truck started to modulate the voltage and cycle the battery after the 2 minutes of being at 15.3v. Kind of weird it was keyed to 500 miles .......independent of the 30 degree temperature swings we had today in NY.

[sdeeter19555]

I've seen as high as 15.1V on my insight, never gotten close to 16V.

 

Sent from my SAMSUNG-SM-G900A using Tapatalk

[bakerk2]

Kind of why I was freaking out. You'd never know by looking at the dash. 15.3 (where my 15 would run) and 16 look pretty similar. IT was the radar detector that was losing its mind. The computer is now modulating the voltage over 501 miles (with key cycle). Just adding more info to this thread. I'm super relieved!

[Coby7]

One concern I would have with connecting the two neg posts together is that now ALL of the current produced by both batteries now has to share the factory neg lead, which is now most likely undersized. In a perfect, albeit unlikely scenario, this could cause a fire.

Why would current increase, all your doing is sharing the load between the 2 batteries. The only way the ECM can monitor the load is by connecting the 2 negatives of the batteries together with the shortest and biggest lead possible.

[bdbake01]

Why would current increase, all your doing is sharing the load between the 2 batteries. The only way the ECM can monitor the load is by connecting the 2 negatives of the batteries together with the shortest and biggest lead possible.

 

Simply having two batteries doesn't increase the current. You're absolutely correct, you'll just share the load between the two, all things being equal. But...then I wonder why are you doing this again?

 

Increasing the load along with additional battery capacity (two batteries) will increase the current on the factory ground if you only connect the two neg posts together leaving the factory negative lead on the original battery.

 

The OEM lead is only sized to handle the maximum continuous current of the single OEM battery plus the infrequent overload of activities such as starting the engine. If you connect two batteries in parallel by their posts and keep the OEM negative lead to the chassis AND increase the continuous load on the battery system (by adding, say, a microwave) then you'll likely exceed the maximum continuous rating of the negative lead and run into problems. Such as fire. You'll make fire.

[Coby7]

That ground wire is 3/8" around, it's going to take a lot of juice for it to catch fire. The most current it's going to see is on start-up and that hasn't changed.

[Colby_in_AZ]

On ‎10‎/‎3‎/‎2016 at 11:20 AM, sunryz76 said:

any help is appreciated. Thanks!!

Did you ever get resolution on this topic?  My wife's 2015 Suburban SLT is doing the same thing.  Voltage drops and causes the blower to drop out, shift strangely.  Dealership couldn't find anything wrong with it.

[IASilverado]

Any updates on this? My 17 is going as low as 12.6 volts and is causing issues with the fuel pump. It keeps setting a p2635 code when it drops this low.