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Sierra 18-6851 Battery Isolator 1-Alternator 2-Battery 130 Amp

Manufacturer

Sierra

<p>For nearly six decades, Sierra has established itself as one of the marine industry's most trusted names in aftermarket engine and drive parts. Founded as a specialized marine parts manufacturer, Sierra has grown into a comprehensive supplier of replacement components, instrumentation, and accessories for both recreational and commercial boating applications. Operating from their 300,000-square-foot distribution center in Litchfield, Illinois, Sierra serves boat owners and marine technicians worldwide with an extensive catalog of parts engineered specifically for the harsh saltwater environment.</p><h3>Marine Engine Excellence</h3><p>Sierra's reputation was built on delivering precision-engineered internal engine components and drive system parts that meet or exceed OEM specifications. Their <a href="/7570-sierra-engine-gasket-set-5404">engine gasket sets</a> provide critical sealing solutions for inboard and outboard motors, while their <a href="/7570-sierra-engine-complete-assembly-15341">engine complete assemblies</a> offer comprehensive replacement options for major overhauls. Each component undergoes rigorous testing to ensure reliability in demanding marine conditions, from corrosion resistance to temperature cycling performance.</p><h3>Instrumentation and Monitoring Systems</h3><p>Accurate instrumentation is essential for boat operators to monitor engine health and prevent costly breakdowns on the water. Sierra's comprehensive line of <a href="/7570-sierra-gauges-200483">gauges</a> includes everything from fuel pressure and temperature indicators to voltmeters and trim gauges, all designed with marine-grade materials that withstand vibration, moisture, and UV exposure. Their <a href="/7570-sierra-tachometer-gauge-1488">tachometer gauges</a> deliver precise RPM readings critical for optimizing engine performance and fuel efficiency. Supporting these instruments, Sierra's <a href="/7570-sierra-gauge-resistor-47908">gauge resistors</a> ensure proper signal conditioning and accurate readings across various sensor types and engine configurations.</p><h3>Expanded Product Portfolio</h3><p>In 2022, Sierra significantly broadened its scope beyond traditional marine engine parts to encompass a wider range of boating accessories and even outdoor power equipment components. This strategic expansion brought established marine brands like Shields and Moeller under the Sierra umbrella, creating a one-stop resource for marine maintenance and replacement parts. The company now offers fuel systems, electrical components, battery charging solutions, and NMEA electronics alongside their traditional engine parts lineup.</p><h3>Quality Backed by Industry-Leading Warranties</h3><p>What sets Sierra apart in the crowded aftermarket marine parts market is their commitment to standing behind every component they manufacture. Their warranty coverage extends beyond simple part replacement—it includes shop labor, haul-out fees, towing charges, and related incidental costs should a warrantied part fail. This comprehensive protection reflects the company's confidence in their manufacturing processes and quality control standards. For boat owners facing repairs far from shore or mechanics working on customer vessels, this peace of mind is invaluable. Whether you're maintaining an outboard motor, rebuilding an inboard engine, or upgrading your boat's instrumentation, Sierra's decades of marine industry experience and commitment to quality make them a reliable choice for keeping your vessel running at peak performance.</p>

Part Number

18-6851
06/21/2036 4:08 PM
Sale Price

$174.67

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Product Details

The Sierra 18-6851 battery isolator enables you to charge two separate battery banks from a single alternator source, making it ideal for marine vessels, RVs, and other applications requiring isolated battery systems. This 130-amp isolator ensures that your starting battery remains fully charged while also maintaining your auxiliary or house battery bank.

Key Features:

  • 130-amp continuous duty rating for reliable performance
  • Charges two battery banks from one alternator source
  • Prevents battery discharge between banks when engine is off
  • Solid-state design with no moving parts for long service life
  • Heat sink construction for efficient thermal management
  • Simple installation with clearly marked terminals

Important Compatibility Note: This isolator is not compatible with Delco "CS" style alternators. Verify your alternator type before installation to ensure proper operation.

Battery isolators are essential for maintaining separate electrical systems, allowing you to run accessories and house loads without risking the depletion of your starting battery. The Sierra 18-6851 provides dependable isolation and charging management for dual-battery configurations.

Products specifications

Amps

130

Application

1 alternator / 2 batteries*

Best prices I've found. Shipping was fast never had any issues bought multiple things from them and do plan on going back.

Great price and fast shipping...took only 2 days to deliver. Very satisfied customer

Didn't see military/LEO discount =(

A few items could have a better description.

easy to find and purchase the item i was looking for

Great!

Website is easy to use.

Easy to navigate, fast shipping and able to get parts that are practically discontinued. Great experience.

Very quick and easy to order. Looking forward to the speedy delivery :)

Not bad price

First time like it so far

Great online experiance

Easy thanks!

Best prices anywhere!!!

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