what type of power runs continuously from the start battery to auxiliary to charge it through the cable???

When the isolator reads the need to charge the second battery it will be charged with the alternator of the vehicle

Does this item have an internal fuse? Do I only need to fuse my auxiliary battery?

No it does not. I highly recommend installing a re-settable 150A fuse between your main battery and the isolator.

Can I use this to connect 2 RV batteries in parallel with differet amperage so that the leisure battery only kicks in when the primary battery low?

So they are connected in parallel when charging. The batteries can be of different amperages. However if the non stater battery drops below 12.8 volts it will disconnect from the system so your starter battery does not discharge. Starter and non-starter battery connections are labeled. The yellow wire coming out of the controller can be connected to a switch with the other side connected to ground. If you move the switch so yellow wire goes to ground it will bypass the disconnect and connect both batteries in parallel regardless of the voltage of either battery. Hope this helps.

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MaySpare Dual Battery Isolator Kit 12V 140Amp Voltage Sensitive Relay VSR Double Battery Automatic Charger & Wiring Cable Kit

MaySpare Dual Battery Isolator Kit 12V 140Amp Voltage Sensitive Relay VSR Double Battery Automatic Charger & Wiring Cable Kit

Product ID: 173975296

Details

Connector Type
Screw
Contact Material
Silver
Contact Type
Normally Open
Current Rating
140 Amps
Mounting Type
Panel Mount

⚡140A high current capacity

🔋12V power system

🔌Auto voltage-sensitive relay

HK$772

Duties & taxes included

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Description

🔋 Power up your adventures with flawless dual battery control!

VERSATILE COMPATIBILITY - Compact design fits perfectly in ATVs, UTVs, boats, RVs, trucks, and caravans.
COMPLETE INSTALLATION KIT - Includes all wiring and connectors for a hassle-free, professional-grade setup.
SMART VOLTAGE SENSITIVITY - Engages at 13.3V and disengages at 12.8V to optimize battery health and prevent power drain.
SEAMLESS DUAL BATTERY MANAGEMENT - Automatically isolates and charges two batteries, ensuring your main battery is always ready to start.
RELIABLE HIGH CURRENT PERFORMANCE - Handles up to 140 amps with silver contacts for durable, efficient power transfer.

The MaySpare Dual Battery Isolator Kit is a 12V, 140A automatic voltage-sensitive relay system designed to manage two batteries efficiently. It ensures your main battery remains charged and ready by isolating it from auxiliary batteries, activating at 13.3V and disengaging at 12.8V. The kit includes all necessary wiring for easy installation and is compatible with a wide range of vehicles including ATVs, boats, RVs, and trucks.

Specifications

ASIN	B081JL6ZXP
Best Sellers Rank	#158,590 in Automotive ( See Top 100 in Automotive ) #14 in Automotive Replacement Battery Relocation Kits
Brand Name	MaySpare
Coil Voltage	12 Volts
Connector Type	Screw
Contact Current Rating	140 Amps
Contact Material	Silver
Contact Type	Normally Open
Current Rating	140 Amps
Customer Reviews	4.4 4.4 out of 5 stars (370)
Manufacturer	MaySpare
Minimum Switching Voltage	13.3 Volts
Mounting Type	Panel Mount, Surface Mount
Number of Terminals	3
Operation Mode	Automatic
Part Interchange Info	Voltage Sensitive Relay
Part Number	US-Battery kit
UPC	742089521075

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Our prices include the product cost, international shipping, import duties, customs clearance, and local delivery charges. We handle all customs and import procedures, ensuring there are no hidden fees upon delivery. PRO members receive additional benefits including free shipping.

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HK$772

Duties & taxes included

In stock

Sold byAmazon Hong KongDelivered byDesertcartCustomer service byDesertcartReturns14 days · 30 with PRO

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TrustScore 4.5 | 7,300+ reviews

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