True® Marine Battery Isolators 12V 140A Automatic Voltage Sensitive Relay

⚓ True® Marine Battery Isolator — Core Features

• 🔋 Smart Dual Battery Management
  Automatically manages charging between starting and auxiliary batteries, ensuring your engine battery stays protected while accessories stay powered.
• ⚡ Voltage-Sensing Technology
  Detects battery voltage levels and connects/disconnects batteries without manual switches—fully automatic operation.
• 🌊 Marine-Grade Durability
  Waterproof and corrosion-resistant housing built to withstand harsh marine environments, from salt spray to engine heat.
• 🛠️ Compact & Easy Installation
  Designed for tight compartments with simplified wiring and multi-angle stud placement for flexible cable routing.
• 🔒 Ignition Spike Protection
  Shields sensitive electronics from voltage surges during engine start-up or shutdown.
• 💡 LED Status Indicators
  Provides visual feedback on battery connection status for quick diagnostics and peace of mind.
• 🔄 Universal Compatibility
  Works with lithium, AGM, and lead-acid batteries across all 12V marine charging systems.
• 12V / 140A Output — Consistent, high-capacity performance
•  Surge Protection Built-In — Defends against ignition-related voltage spikes
• PEP® Technology – Peak Efficiency Performance for unmatched power delivery in lithium dual setups
• Compact & Tough Design — Reinforced housing with strategically placed studs for hassle-free cable connections from any angle
• Fully Automatic Operation — No manual switching, just smart, effortless control
• Zero Voltage Drop — Delivers full power with no compromise
• Lifetime Flat-Fee Replacement — Adventure boldly, we’ve got you covered
• Maintenance-Free Operation — More exploring, less tinkering

These isolators are ideal for boats with trolling motors, navigation systems, lighting, and other onboard electronics—keeping everything charged and protected without draining your starter battery.

Standard kit composition

•  1 (SBI) Smart Battery Isolator install kit with mounting screws
•  #6 high flex red cable with tinned copper cable lugs
•  #6 high flex black cable with tinned copper cable lugs
•  2 positive brass alloy battery terminal ends
•  1 negative brass alloy battery terminal end
•  3 loose crimp-on tinned copper cable lugs
•  2 sections of adhesive lined shrink tube
•  5 zip ties
•  1 – 2nd battery kit installation booklet
• 12v dual battery wiring kit diagram included
• Official retailer of True® dual battery relay kit
• Delivery: USPS first class or priority mail

How do I install a marine battery isolator?

To lessen voltage drop, install the isolator close to the batteries.
Use fuses and wiring that are gauged correctly (for high-current setups, use 150A fuses and 4 AWG cables, for example).
Before installation, turn off shore power to prevent short circuits.

Manual vs. Automatic isolators—what’s the difference?

Switching between batteries with a manual isolator requires user intervention.
Boats with variable engine runtime benefit greatly from automatic isolators, which, like voltage-sensitive relays, activate when the charging voltage surpasses a threshold (for example, 13.2V).

Unlike traditional diode-based isolators, True® Smart Isolators use advanced MOSFET technology for near-zero voltage drop, maximizing charge efficiency and battery lifespan. Whether you’re outfitting a weekend cruiser or a commercial vessel, True® delivers peace of mind with every charge.

🌟 Key Benefits of True® Marine Battery Isolators

• 🔋 Protects Your Starter Battery
  Prevents auxiliary loads (like lights, radios, and pumps) from draining your engine-starting battery, ensuring reliable starts every time.
• ⚡ Automatic Voltage Sensing
  No need for manual switches—these isolators detect voltage levels and connect/disconnect batteries automatically.
• 🌊 Built for Marine Conditions
  Waterproof and corrosion-resistant housing stands up to saltwater, humidity, and engine heat.
• 🔄 Efficient Dual Battery Charging
  Charges both batteries from a single alternator without rerouting ignition wiring, saving time and complexity.
• 🔒 Ignition Spike Protection
  Shields sensitive electronics from voltage surges during engine start-up or shutdown.
• 🧠 Smart Power Management
  Keeps your onboard systems powered while isolating batteries during discharge, extending battery life and improving safety.

Whether you’re running a trolling motor, GPS, or a full suite of electronics, these isolators keep your power flowing smoothly while protecting your gear. Want help choosing the right kit for your boat size or battery type?