True® Car Second Battery Kit , Trucks, RVs, Automatic Isolator & Heavy-Duty 12V 140A

(1 customer review)


True® 12V 140A automatic second battery isolator kit for 4-wheel vehicles is designed for heavy-duty performance and known for durability, waterproof cables, 360-degree heat resistance, anti-vibration casing, and an easy-to-install isolator kit.

  • Priority charging for starting battery
  • 140 Amp Voltage Sensitive Relay (VSR)
  • Automatic Battery Management
SKU: DBK12LARGE2 Category:


Second Battery Kit Inclusion:

    • 1 (SBI) True Smart Second Battery Isolator complete with mounting screws
    • 20 feet #6 high flex red cable with tinned copper cable lugs
    • 3 feet #6 high flex black cable with tinned copper cable lugs
    • 2 positive brass & 1 negative brass alloy battery terminal ends
    • 3 loose crimp-on tinned copper cable lugs
    • 2 sections of adhesive lined shrink tube
    • 5 zip ties &  1 manual for installation
    • FREE Shipping for the US and Canada.
    • Delivery: USPS first class or priority mail
    • 1 Year Manufacturer’s Warranty
    • 1-day dispatch

True® Secondary Car Battery Kit is Easy to Install

Years in research and innovation enable us to design a complete second battery install kit for any type of vehicles  The long cable and anti-corrosion brass allows you to conveniently position the secondary battery isolator inside the engine compartment.  Each second battery wiring kit has a printed wiring diagram and instruction manual which is also downloadable here.

(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.)


Truck Camper Shell Inverter Install and Dual Battery Setup
Truck Camper Shell Inverter Install and 2nd Battery Isolator Kit for Car Audio


The True® smart second battery isolator wiring kit is unique in that it is truly “smart.” When there is more power available beyond the required amount by the primary electrical system and its function, it knows exactly when to connect and detach to provide for the charge of the secondary battery.

True® Secondary Battery Isolator Auto Detection (VSR)

The True® second battery kit for car audio ability to operate in a dual battery management system for vehicles boils down to the unit reading the mind of the available charging source and using that power to charge your second battery for all those accessories while disconnecting and isolating the batteries from each other when too much energy is being used. True® car second battery isolator guarantees that your starting battery has enough energy to perform its primary function of starting the engine at all times.

2nd battery for car audio and other accessories
2nd battery for car audio and other accessories

Our Expert is You

Rather than trusting an engineer to design something that suits a conceptual setting, the people at True® have spent more than 8 years listening to the very users of these car second battery kit  for car audio to truly determine what is needed in practical applications. The development and testing laboratory has been back roads, forests, mountains, deserts, sand dunes, jungles, rain forests, and wherever else you travel.

True® altered, modified, rebuilt, and most importantly, listened to the feedback gathered to create items that are “appropriate” for the application of the best second battery kit for car audio.




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Additional information



1 review for True® Car Second Battery Kit , Trucks, RVs, Automatic Isolator & Heavy-Duty 12V 140A

  1. jkru617

    I am using this on my 2020 F150 to put an extra battery in the bed. I had heard mixed reviews on if it would work with the type of alternator I have but it worked great. I ran a fridge off my battery in the back and it charged up every time I went somewhere with the truck. Truck battery stayed full too. Im an idiot with electricity but the instructions are straight forward.

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