{"product_id":"blue-sea-systems-add-a-battery-kit-120a-automatic-dual-bank-marine-battery-manager-corrosion-resistant","title":"Blue Sea Systems Add-A-Battery Kit 120A — Automatic Dual-Bank Marine Battery Manager, Corrosion-Resistant","description":"\u003cp\u003e\u003cstrong\u003eBlue Sea Systems Add-A-Battery Kit, 120A is an automatic dual-bank battery management kit that combines a Dual Circuit Plus switch with an Automatic Charging Relay to charge both starter and house batteries while isolating them at rest.\u003c\/strong\u003e\u003c\/p\u003e\n\n\u003cp\u003eDesigned for inboard engines and larger outboards, this kit provides a straightforward, reliable way to manage two battery banks without external isolators or complex regulators. It senses charging voltage, links batteries while the engine or charger is running, and separates them when voltage falls—protecting electronics and preserving starting power. Built with marine-grade components and a 120 amp continuous rating, the system is meant to handle the demands of harsh, corrosive marine environments.\u003c\/p\u003e\n\n\u003ch3\u003eHow does the Add-A-Battery Kit keep my starter and house batteries properly managed?\u003c\/h3\u003e\n\u003cp\u003eThe kit uses a Dual Circuit Plus switch to let the starter and house banks operate independently while providing a single ON\/OFF control for routine use. An integrated Automatic Charging Relay detects when charging voltage is present and momentarily parallels the banks so both receive charge. When charging stops, it isolates the banks to prevent house loads from depleting the starter battery.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eDual Circuit Plus switch separates starter and house circuits with one simple control\u003c\/li\u003e\n  \u003cli\u003eAutomatic Charging Relay senses voltage and combines banks only during charging\u003c\/li\u003e\n  \u003cli\u003ePrevents parasitic discharge onto the starter battery when at rest\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhat happens if one battery is dead and I need to start the engine?\u003c\/h3\u003e\n\u003cp\u003eThe kit includes an emergency combine or parallel feature that lets you link both batteries temporarily for engine starting if one bank is discharged. This manual combine protects against being stranded while still allowing normal isolation during everyday operation. Use the combine only briefly to start, then return the switch to normal to restore isolation.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eIntegrated emergency combine connects both banks for starting power\u003c\/li\u003e\n  \u003cli\u003eManual operation ensures you control when batteries are paralleled\u003c\/li\u003e\n  \u003cli\u003eReturn to normal position after start to prevent unnecessary battery drain\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eIs this kit durable enough for marine conditions and heavy use?\u003c\/h3\u003e\n\u003cp\u003eYes — the Add-A-Battery Kit is built specifically for marine exposure, using corrosion-resistant tin-plated copper studs and components designed for continuous current up to 120 A. Materials and finishes help reduce corrosion and maintain conductivity in salty, humid environments, so the kit continues to perform reliably season after season. Its construction supports installation on inboards and larger outboards where higher continuous currents are common.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eTin-plated copper studs resist corrosion and maintain good conductivity\u003c\/li\u003e\n  \u003cli\u003e120 A continuous rating suits inboards and larger outboard setups\u003c\/li\u003e\n  \u003cli\u003eRugged design for marine vibration and moisture conditions\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eHow does installation simplify my boat's electrical layout?\u003c\/h3\u003e\n\u003cp\u003eThe Add-A-Battery Kit reduces wiring complexity by combining switching and automatic charging relay functions into a single, coherent kit. Instead of separate isolators or complex regulator wiring, this solution centralizes battery management and provides clear ON\/OFF and emergency combine control. That decreases the chance of switching errors and makes routine operation easier for owners and crew.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003eCombines switch and relay functions to cut down on extra components\u003c\/li\u003e\n  \u003cli\u003eSingle ON\/OFF operation streamlines everyday battery control\u003c\/li\u003e\n  \u003cli\u003eClear manual combine option reduces confusion during emergencies\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eWho this is for: The Blue Sea Systems Add-A-Battery Kit, 120A is ideal for boat owners with separate starter and house banks—especially those with inboard engines or larger outboards who need reliable automatic charging and straightforward emergency paralleling. It suits sailors, cruisers, and powerboat operators seeking a durable, low-complexity way to keep both batteries charged while protecting starting capacity and sensitive electronics.\u003c\/p\u003e\n\u003csection class=\"product-faq-snippet\"\u003e\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Will this kit charge both batteries from my alternator?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes. The Automatic Charging Relay senses alternator voltage and parallels the banks during charging so both batteries receive charge.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"faq-item\"\u003e\n\u003cp class=\"faq-q\"\u003eQ: Can I combine batteries manually if one is flat?\u003c\/p\u003e\n\u003cp class=\"faq-a\"\u003eA: Yes. The kit includes an emergency combine feature to link both banks temporarily for starting.\u003c\/p\u003e\n\u003c\/div\u003e\u003c\/section\u003e","brand":"Blue Sea Systems","offers":[{"title":"Default Title","offer_id":55170371223895,"sku":"B000RZNP5K","price":208.48,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1050\/1524\/7191\/files\/blue-sea-add-a-battery-front.jpg?v=1790428598","url":"https:\/\/britishgarage.co.uk\/products\/blue-sea-systems-add-a-battery-kit-120a-automatic-dual-bank-marine-battery-manager-corrosion-resistant","provider":"British Garage","version":"1.0","type":"link"}