12v-isolator-kit
12v-isolator-kit
12v-battery-isolator-switch
True® GMC Sierra Dual Battery Kit 12V 140A Automatic Management - Image 4
True® GMC Sierra Dual Battery Kit 12V 140A Automatic Management - Image 5

True® GMC Sierra Dual Battery Kit 12V 140A Automatic Management

(8 customer reviews)

Price range: $132.95 through $152.95

The True® brand is the best smart battery isolator kit for the GMC series! Made in the USA, the True® – GMC® dual battery kit is a heavy-duty 12v & 14A battery management system known for being compact, easy to install, waterproof, and heat-resistant.

  • Automatic 140A Smart Battery Management
  • Transparent Case with LED Indicator
SKU: DBK12LRG-GMC Category:

Description

Brand Compatibility

Compatibility

This 9th generation 12v heavy-duty GMC Sierra dual battery kit is a superior product that uses a very unique designed and programmed SBI (PEP) when it comes to dealing with the stator charging mechanism.

A TRUE exclusive!

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Here are some of the True® GMC® Sierra dual battery kit advantages:

GMC Sierra

  1. It is assembled in America and delivers through first-class mail.
  2. It has advanced specific internal programming for maximum efficiency with automotive stators. (PEP)
  3. Its new case was introduced last April 2019 specifically designed for automotive application.
  4. It has a superior cable construction with 100 % waterproof shrink tube.
  5. It offers extra flex cables for easy routing.
  6. It assures correct cable ends to custom fit isolator studs.
  7. The new smart GMC Sierra dual battery kit can be left suspended in-line, as long as it is mounted with provided 3M Dual Lock™, or hard mounted with any provided screws.
  8. It is compatible with all battery types like dry cell, flooded lead-acid, AGM, and any hybrid.

With its upgraded features, the TRUE® Smart 12v isolator switch is specifically designed and programmed for automotive and marine application, plus it is  100% American-made.

 

An important note from the designer:

 

“The TRUE® 12v battery isolator switch is the 9th generation I have designed. The first-generation products which I have designed before I figured the proper programming include the QUAD BOSS/AOPEC/Keyline units.

Together with PEP (Propriety Efficiency Programming), the all-new TRUE® isolator kits have added lots of upgrades which include the case design, circuit board design, and the type of cables that should be used in order to avoid insulation and terminal failures from possible corrosion.

 Overall, its main goal is to provide stable and easy installation. The construction of the actual 12v GMC Sierra dual battery kit case has been exclusively redesigned for automotive application which then allows a hassle-free and versatile installation. There are possible cable access slots that need to be “knocked out” because it may cause a breach in the seal protecting the circuit board, which is why the front mounted studs are there to eliminate unnecessary holes.

Now, we made sure to move all our production processes as possible to America. These improvements made huge impacts that are essential for the benefit of all because we only aim to provide the best and most efficient products that fit the standards and demands of a vehicle’s owner. True is a heavy-duty and universal dual battery kit for Sierra, Yukon, Terrain, Canyon, Acadia, Sabana. Yes all GMC® motors are fit for the True® brand. 

Dennis M. Hogan, Ph.D.
TrueAm Inc.

Testimonials from Our Amazon Store

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Frequently Asked Questions

Do I need to run a ground wire from the auxiliary battery to the main battery?
Yes, it is highly recommended. On modern GMC/Chevy trucks with a current sensor on the negative battery terminal (often on the starting battery), you must connect the negative terminal of the auxiliary battery directly to the negative terminal of the starting battery. Failing to do this can cause the truck’s voltage regulator to cut alternator output, leading to undercharging and premature battery failure for both batteries.

Yes. It is a safety precaution to add an extra inline fuse or circuit breaker between the main battery, the isolator, and the auxiliary battery. A common recommendation is a 100-140 amp fuse or breaker on the line coming from the second battery.

The indicator light (often blue or on a separate voltmeter) illuminates when the isolator is engaged, letting you know that the auxiliary battery is currently being charged from the alternator.
The isolator engages (connects both batteries for charging) when the system voltage reaches 13.3V or higher (indicating the alternator is charging). It disengages (isolates the batteries) when the voltage drops to 12.8V or below (when the engine is off).
The technology is generally warranty-friendly and requires NO connection to the alternator or ignition system. It uses a voltage-sensitive relay (VSR) for automatic management.
Yes, the isolator features an IP65 rating for water, dust, and vibration resistance, making it ideal for harsh automotive, marine, or off-road environments.

📦 Kit Inclusions

What’s in the Kit

  • 1 × True® Smart Battery Isolator (SBI) with mounting screws
  • 20 ft × #6 AWG high-flex red cable with tinned copper lugs
  • 3 ft × #6 AWG high-flex black cable with tinned copper lugs
  • 2 × Positive brass alloy battery terminal ends
  • 1 × Negative brass alloy battery terminal end
  • 3 × Loose crimp-on tinned copper cable lugs
  • 2 × Adhesive-lined shrink tubes
  • 5 × Zip ties
  • 1 × Installation instruction booklet

🔋Features

The True® Dual Battery Isolator stands out for its smart design, rugged durability, and ease of use — making it a top choice for off-roaders, campers, and audio enthusiasts. Here are its best features:

 Best Features of the True® Dual Battery Isolator

  1. Automatic Voltage Sensitive Relay (VSR)
    • Engages at 13.3V and disengages at 12.8V, ensuring your main battery stays charged while your auxiliary battery powers accessories.
  2. Solid-State Design
    • No moving parts means greater reliability and longer lifespan — ideal for harsh environments like marine, off-road, or high-vibration setups.
  3. IP65 Rated for Water, Dust, and Vibration Resistance
    • Built to withstand extreme conditions, making it perfect for 4WDs, boats, RVs, and work vehicles.
  4. Compact and Easy to Install
    • Fits neatly into tight spaces and includes clear instructions. Some kits even come with silicone insulators and 3M dual lock fasteners for secure mounting.
  5. LED Voltmeter and Dual Display (on select kits)
    • Lets you monitor battery status at a glance — a handy feature for managing power on the go.
  6. Prevents Battery Drain and No-Start Situations
  • Keeps your starting battery isolated from accessory loads, so you never get stranded due to a dead battery.

📸 Photo & Video

 

(These videos are not endorsed or represented as an “Official Installation video” by True Amalgamated and True Amalgamated accepts no responsibility for its content. It is produced by the end-user as stated. Follow entirely at your own risk.)

      Dual battery setup with isolator kit in RV 2019 GM Truck dual battery setup video

🚚 Shipping

Orders are shipped via USPS First Class or Priority Mail, with up to $100 insurance included.

Most orders are processed within 1–3 business days and come with tracking.

The company aims for same-day shipping if placed before 2:30 PM PT, excluding weekends and U.S. federal holidays.

Best of all, shipping is free—no hidden fees.

Additional information

Location

USA, CANADA, AUSTRALIA

8 reviews for True® GMC Sierra Dual Battery Kit 12V 140A Automatic Management

  1. Noah Johnson –

    This was installed in a full-size 2010 GMC Sierra, along with a marine battery as the backup. It was simple to set up and works perfectly. The package had everything. The only difference was that I soldered the eyelets onto the wire rather than crimping them. That may be accomplished by heating the eyelets with a tiny butane flame and just feeding the solder in until it is bonded. Crimping provides a better electrical contact.

  2. Oliver MIller –

    True battery isolator is a local company in USA, and I was impressed with how easy it is to use and how complete it is.

    The only thing you need to add as a safety precaution, as they propose, is an extra inline fuse coming from the second battery, preferably a 100-140amp fuse.

    Which I obtained after viewing a couple setup videos on YouTube.

    April 5, 2023

  3. Joeseph Florence –

    Every time I go home, I have to turn on the trickle charger for my two series batteries so my truck will start up the following day. My air compressor kicks in most of the time, therefore I have to flick the key multiple times to start the truck.

    I initially believed that I might need to purchase a new starter, but after using the Sierra 1500 battery isolator, the vehicle has been starting for the past three weeks without the trickle charger on. The product functions properly.

  4. EmerTiu –

    This is a great dual battery kit. I put USB ports, an inverter, and a second 100 amp Renogy AGM battery in the back of my GMC Sierra 1500 canopy. Simple wiring with unambiguous directions.

  5. Correy F –

    Arrived with every detail I needed to put a dual battery kit in my Sierra 1500 to power all of my accessories, which made me very happy.

  6. Steve Hoggen –

    This was just what I wanted in order to keep both of the batteries in my truck charged. The cord was adequate to connect my starting battery to the batteries at the back of my extended full-size truck.

    The True smart battery isolator for GMC Sierra 1500 worked beautifully, even after I exhausted my batteries twice and traveled countless rough gravel roads. Solar receives a lot of interest, but this is far more beneficial.

  7. Ryan –

    Really simple to install.
    My only issue is the positive terminal on my main battery. I cut it off to use one of the new battery clamps. Well, the old one is a drop style as it runs over the battery. The ones in the kit don’t allow for this. Long story short. I had to rotate my battery 180 to make it work.

    Other than that, this kit is super easy and quick to install. Works well too.

  8. Ricky Hawker –

    This merchant makes an excellent product. All of the gear and wiring required to install the dual battery isolator. Good instructions. I connected the dual battery isolator to an AGM power box in the passenger floor of my Sierra 1500. I wanted to be able to keep track of the dual battery isolator, so I attached a voltage meter to both the main and supplemental batteries. The wire gauge is correct, and everything is operating well. I’m delighted I purchased this stuff.

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