Battery Isolator 12V with 16.4ft 7AWG Cable Kit - Smart 140A Split

In this review the Battery Isolator 12V kit is evaluated for people who need a reliable way to keep an auxiliary battery charged while protecting the main battery from discharge. The single biggest reason to consider it is the automatic voltage sensitive relay, which connects or disconnects the auxiliary battery based on main battery voltage so you do not have to manage isolation manually. The included 16.4ft 7AWG cable kit makes routing easier in larger vehicles, and the IP68 waterproof rating means it was designed for outdoor and marine use.

Key Features

• Automatic Voltage Sensing: The relay connects the auxiliary battery when the main battery reaches charging voltage, allowing both batteries to be charged from the alternator simultaneously.
• Built-in Protection: The circuit automatically disconnects if input voltage falls below 11V or rises above 17V to prevent over discharge and overvoltage on the main battery.
• Long Cable Kit: The 16.4ft 7AWG battery cable included in the kit provides length for flexible installation in trucks, RVs, and boats.
• High Current Capacity: The 140AMP split charge relay handles typical alternator charging currents for dual-battery setups without frequent thermal issues.
• Weatherproof Build: The IP68 waterproof rating lets the isolator sit in exposed or damp locations common to marine and offroad installations.

Who It's For

The kit is well suited to vehicle owners who run accessories off an auxiliary battery and want automatic charging without manual switching, including RV users, 4x4 enthusiasts, boat owners, and owners of ATVs or UTVs. The long 16.4ft 7AWG cable and compact isolator body make it a good fit where routing and space are constraints.

It is not appropriate for systems that rely on ternary lithium battery chemistry, as the product is explicitly not compatible with those cells. Buyers needing a battery isolator tailored specifically for advanced lithium battery management or integrated battery management systems should look elsewhere.

Pros & Cons

Pros

• Automatic voltage sensing simplifies dual-battery charging without manual switching.
• IP68 waterproof rating increases suitability for marine and offroad use.
• Long 16.4ft 7AWG cable makes installation easier in larger vehicles.
• Built-in low and high voltage thresholds protect the main battery from damage.

Cons

• Functionality reports are mixed from customers, so some installations may require troubleshooting to achieve expected operation.
• Not compatible with ternary lithium battery chemistries, limiting use with newer lithium systems.

Specifications

Product Type	12V Smart Voltage Sensitive Relay
Current Rating	140AMP split charge relay
Cable Kit	16.4ft 7AWG battery cable included
Voltage Protection Range	Disconnect under 11V or over 17V
Waterproof Rating	IP68
Compatible Vehicles	RVs, cars, ATVs, UTVs, boats, 12V DC systems

Our Verdict

The Battery Isolator 12V kit is a practical, affordable solution for keeping an auxiliary battery charged while protecting the main battery, especially for recreational vehicles, offroad rigs, and marine use. Its automatic voltage sensitive relay, long 16.4ft cable, and IP68 rating deliver good value for most 12V dual-battery setups, though owners of ternary lithium batteries should choose a different product.

Frequently Asked Questions

Will this kit charge both batteries while driving?
Yes, the voltage sensitive relay connects the auxiliary battery to allow simultaneous charging from the alternator when the main battery is at charge voltage.

Can it be installed outdoors or on a boat?
Yes, the isolator has an IP68 waterproof rating designed to withstand wet and harsh conditions.

Is it compatible with ternary lithium batteries?
No, the product is explicitly not compatible with ternary lithium battery chemistries.