Would it make any sense to install a 1-2-BOTH-OFF switch for a dual batt setup?

[5StarCustmSolutns]

Aside from being able to disconnect all in the event of an off-road accident, is there a practical use for one?

Ask because in looking for info on this over the weekend, I came across this doc.

https://www.gmupfitter.com/wp-content/uploads/2021/05/2011_LD_ElectricalPickupsChassisCabs_100813.pdf

At first I wasn't sure if it even applied to our vehicles, but after looking over diagram on A-11 I changed my mind. Then again on A-27 > A-33 put to rest my lingering doubts...

But what I found fascinating was the info on batteries, grounds, and aftermarket accessories from A-13 > A-22. On A-22 the Auxillary Batt charging, to me, reads like there is an onboard relay if use STUD 1 Fuse 68 for accessories? as described on A-16(?)....


I feel like @swathdiver has read this and could pull out the physical copy, when properly staged, faster than my LC9 can pass a 1/4mi strip of pavement....

Part of me still thinks that only certain pages pertain to the GMT900 (poorly indicated/marked if so), and that the bulk of this pertains only 3500 dsl's? Fascinating if it does apply though..

And if it does, and it is that intricate, could not a dumb battery swith have a role? If both batt have a constant digital Voltage reading, just switch to the batt in need or to BOTH while running and let the onboard regulate the rest?

 

[5StarCustmSolutns]

@swathdiver Does this apply to the 07-13 GMT900?

Any thoughts on the 1-2-1+2-OFF switch?

 

[mikez71]

For camping type use where you might have a slow draw that might deplete one battery, I think a switch would be great.

My thinking is, the parallel setup is simpler, and will be gentler on the batteries by spreading the load and not running one battery all the way down. BUT you lose reserve capacity..

 

[5StarCustmSolutns]

For camping type use where you might have a slow draw that might deplete one battery, I think a switch would be great.

My thinking is, the parallel setup is simpler, and will be gentler on the batteries by spreading the load and not running one battery all the way down. BUT you lose reserve capacity..

thank you for the insight...

it is camping im concerned about... have 2nd yellow top mounted but not connected, not until I figure switch situation out? have the marine 4pos and a VSR to choose from, and really just dont want another smart anything in my life...

off-road lights and KL5 fan draws mostly only happen when its running...

sleep in it for the HVAC, but it idles until hot or frozen inside then off

reserve starting is what Im hoping to preserve... kind of feel like with the dual voltage gauge I can be SURE i have reserve w/manual switch?

 

[pronstar]

An off switch might be nice to have for theft deterrence.

 

[RST Dana]

This is old school manual battery connectivity from my years of EMS in the 70’s. Our ambulances had dual batteries and we had the option of 1 or both and off. We usually turned the switch to off when at the firehall,parked, etc. Occasionally, some times we our ”friends” would engage the lights and siren equipment while in the off mode, expecting us to power up and get surprised. It only took once! But payback was fun!

 

[5StarCustmSolutns]

An off switch might be nice to have for theft deterrence.

View attachment 486451

a bonus perk.. lol

I really just want to hear someone say it's too old of tech. or It wont work w/this charging system?



side note: How you like youre trutrac??

I put 35" Kenda MT2's on and thought "man....these tires incredible I hardly ever use 4x4 anymore", and like 3 offroad events later I was like "....duhhh you put trutrac into a 14bolt rearend and put them both under the back of this this thing right before deciding to make an off road extreme truck out of it". Be willing to wager MTZ's or STT Pro's or KM3's or just about any good tire would seem extraordinary flanking a 9.5" trutrac

 

[Joseph Garcia]

a bonus perk.. lol

I really just want to hear someone say it's too old of tech. or It wont work w/this charging system?



side note: How you like youre trutrac??

I put 35" Kenda MT2's on and thought "man....these tires incredible I hardly ever use 4x4 anymore", and like 3 offroad events later I was like "....duhhh you put trutrac into a 14bolt rearend and put them both under the back of this this thing right before deciding to make an off road extreme truck out of it". Be willing to wager MTZ's or STT Pro's or KM3's or just about any good tire would seem extraordinary flanking a 9.5" trutrac

Before going to TrueTrac on my truck, I did a bit of research and consulting with gear builders, and they came back with answers similar to what Dr. Google says. It all depends on your intended use of the truck. For me, my truck is a street machine, so I chose TrueTrac.

When choosing between the Detroit Truetrac and the Eaton G80 for off-roading, the Truetrac is the superior choice for predictable handling, seamless daily driving, and durability on varied terrain. The G80 (often called the "Gov-lock") is better suited for low-speed, straight-line mud and snow, but is prone to jarring engagements and high-stress failures.

Detroit Truetrac

• How it Works: It is a helical gear-style, limited-slip differential (LSD). Instead of clutches, it uses worm gears to seamlessly transfer torque to the wheel with the most grip.
• Off-Road Performance: Excellent in dirt, gravel, sand, and deep snow. Because it is "always on" and proactive, it doesn't wait for a wheel to spin before working.
• The Catch: If you lift a tire completely off the ground (e.g., rock crawling), it acts like an open differential and the lifted tire will just spin. Applying slight brake pressure forces the gears to engage and send torque to the grounded wheel.
• On-Road Manners: Nearly invisible. It has perfect daily-driving manners without the chirping or tire-hopping of a traditional auto-locker.
• Durability: Extremely reliable since it contains no wearable clutch packs or electronic solenoids.

Eaton G80

• How it Works: It is a centrifugal, automatic-locking differential used as a factory option on many GM trucks (e.g., Silverado, Sierra). It functions as a standard LSD until one wheel loses traction and spins about 100 RPM faster than the other. This triggers a flyweight mechanism that physically locks both axles together.
• Off-Road Performance: Incredible in a straight line through mud or deep snow. Once it locks, you get 100% of the power to both wheels, which is great for getting unstuck.
• The Catch: The violent, "surprise" lockup can cause the vehicle to lurch sideways on slick or icy pavement. It also disengages at higher speeds or when you let off the gas.
• On-Road Manners/Reliability: Generally fine for normal driving, but often referred to as the "Gov-bomb" in the off-roading community. The sudden shock of engagement under heavy throttle can cause the internal components to break, sometimes destroying the axle housing.

 

[pronstar]

The G80 (often called the "Gov-lock")

AKA “Grenady”
I’m not a fan at all.

Trutrac is a great alternative. Even for Offroad, where a true locker isn’t always the answer.

I put a Trutrac in our Suburban when I regeared it to 3.73 from the factory 3.08. My Silverado will get one + 4.10s when I decide to put 35s on it…came with 3.42 from factory so not terrible. Both trucks run 33s

 

[mikez71]

Coming from a lot of open diff vehicles, I like the G80 for what it is, a cheap locker!

But I do frequently feel the little sideways kick of the G80 in grass and wet roads. Never felt it in my torsen bmw diff..

 

[5StarCustmSolutns]

Before going to TrueTrac on my truck, I did a bit of research and consulting with gear builders, and they came back with answers similar to what Dr. Google says. It all depends on your intended use of the truck. For me, my truck is a street machine, so I chose TrueTrac.

Text book reply [perthenorm] Mr Garcia I didnt know you had a Truetrac..

If I remember correctly there were 6 helical --I guess this wayyy of topic....but it's my OP which was getting zero traction, so who gonna complain, right?-- pinion gears that clamp down on the ends of the axles when in need of traction assistance? Even the c-clip hole "cover" is a beast. It was a hardened tempered steel hockey puck. Just impressive
I read and was slightly concerned about the propensity to act like an open diff when there was no resistance at all from one wheel, as in: if one wheel was airborn when crossing an obstacle diagonally? I have yet to be able to create this scenario.. Actually I have yet to be able to create this outcome.. Ive intentionally created the situation to feel for the loss of traction in prep to apply mild brakes, but not had it manifest yet??

The only thing I would change in the way they describe the ol G80 "GovBomb" would be adding this verbage "when one wheel spins -at a rate of- 100 RPM faster than the other.. The -at a rate of- clarifies that it can happen essentially when sitting still.. Because it only takes half a tire rotation. Mine blew up in a total travel distance length of around 10"... Right foot heavy, tire went from concrete > soft dirt > asphalt at the corner of my driveway. G80 weight swung out, engaged spider gears, tried to make the other side co-operate, and it said Ha! Nope! cant defy laws of physics and boom...
Its a brilliiant system, springs weights and good ol american ingenuity! But it's calulated for normal driving conditions with oe tire weights etc...

 

[5StarCustmSolutns]

I’m not a fan at all.

Its better than no locker, if you know you have it and how it works and play to that? Which I had just learned .... and its impossible to not drive instinctually really.. lol

Trutrac is a great alternative. Even for Offroad, where a true locker isn’t always the answer

My personal exp it is better than a true lock/unlock

regeared it to 3.73 from the factory 3.08

i regear from 308 to 342 thinking to save mpg... hahahahhaahaa

when I decide to put 35s on it

couple makes offer 10.5 and 11" width's. that the route i went. much easier fitment. mine were new LT34.9" x 11.1" R17

 

[pronstar]

Its better than no locker, if you know you have it and how it works and play to that? Which I had just learned .... and its impossible to not drive instinctually really.. lol

Yeah I don’t think there’s a good way to eliminate the harsh activation when the pawl engages.

 

[5StarCustmSolutns]

Coming from a lot of open diff vehicles, I like the G80 for what it is, a cheap locker!

But I do frequently feel the little sideways kick of the G80 in grass and wet roads. Never felt it in my torsen bmw diff..

agree... ive never felt anything but: reassuring smooth forward traction....no matter how hard I put my foot down it just goes

does kind of take away from playtime in the snow and mud. youve got to REALLY commit to do mud donuts, snow takes more steering input to throw the rear out there...cant do it w/throttle only very comfortably...meaning you have to give an almost uncomfortable amount of throttle to drift corners on a country road imho

 

[5StarCustmSolutns]

Yeah I don’t think there’s a good way to eliminate the harsh activation when the pawl engages.

agree... and what i did a poor job of describing was: I had just learned about the G80, and was pumped I had one! I even inferred that easy does it aceleraton would be best... But its just hard to not drive instinctually, and some scenarios warrant stabs of the pedal, etc etc

 

[Fless]

Let's get back on topic, please.

 

[Foggy]

Before going to TrueTrac on my truck, I did a bit of research and consulting with gear builders, and they came back with answers similar to what Dr. Google says. It all depends on your intended use of the truck. For me, my truck is a street machine, so I chose TrueTrac.

When choosing between the Detroit Truetrac and the Eaton G80 for off-roading, the Truetrac is the superior choice for predictable handling, seamless daily driving, and durability on varied terrain. The G80 (often called the "Gov-lock") is better suited for low-speed, straight-line mud and snow, but is prone to jarring engagements and high-stress failures.

Detroit Truetrac

• How it Works: It is a helical gear-style, limited-slip differential (LSD). Instead of clutches, it uses worm gears to seamlessly transfer torque to the wheel with the most grip.
• Off-Road Performance: Excellent in dirt, gravel, sand, and deep snow. Because it is "always on" and proactive, it doesn't wait for a wheel to spin before working.
• The Catch: If you lift a tire completely off the ground (e.g., rock crawling), it acts like an open differential and the lifted tire will just spin. Applying slight brake pressure forces the gears to engage and send torque to the grounded wheel.
• On-Road Manners: Nearly invisible. It has perfect daily-driving manners without the chirping or tire-hopping of a traditional auto-locker.
• Durability: Extremely reliable since it contains no wearable clutch packs or electronic solenoids.

Eaton G80

• How it Works: It is a centrifugal, automatic-locking differential used as a factory option on many GM trucks (e.g., Silverado, Sierra). It functions as a standard LSD until one wheel loses traction and spins about 100 RPM faster than the other. This triggers a flyweight mechanism that physically locks both axles together.
• Off-Road Performance: Incredible in a straight line through mud or deep snow. Once it locks, you get 100% of the power to both wheels, which is great for getting unstuck.
• The Catch: The violent, "surprise" lockup can cause the vehicle to lurch sideways on slick or icy pavement. It also disengages at higher speeds or when you let off the gas.
• On-Road Manners/Reliability: Generally fine for normal driving, but often referred to as the "Gov-bomb" in the off-roading community. The sudden shock of engagement under heavy throttle can cause the internal components to break, sometimes destroying the axle housing.

The one note about the Detroit TrueTrac that I don't like is that you can't use
synthetic gear oil. The synthetic additive act like a "posi additive" and screw
it up. You have to use old fashioned 80-90w mineral gear oil without any additive.
I own 3 detroits in my ford aftermarket built rears. I love it !!!
Great street manners and total lockup at the dragstrip