- Purpose: This voltage sensitive relay is designed for two battery systems. Suitable for acid-lead batteries, not suitable for lithium batteries. It allows two separate power sources while charging from one alternator, enabling charging and isolation of two battery systems. - VSR operation: The KeyLine Automatic 12V 140 Amp Dual Battery Isolator uses a voltage sensitive relay that engages at 13.3 volts and disengages at 12.8 volts to keep the primary battery charged and ready to start. - Features: The dual power isolator uses an imported power management chip for intelligent automatic management. It offers strong waterproofing, low loss, good heat dissipation, and high efficiency. - Compatibility: Suitable for DC 12V two-battery systems that require isolation and charging. Universal for car, vehicle, RV, ATV, UTV and boat, and other two-battery electrical equipment. - Benefits: Keeps the starting battery charged while powering a secondary circuit, prevents reverse draining, and simplifies charging from a single alternator. - Use scenarios: - In a car or RV, charges a second battery from the alternator while the engine runs, keeping electronics powered without draining the starter battery. - In a boat or off-road vehicle, isolates the auxiliary battery bank from the starter battery while charging both from one alternator. - For ATVs/UTVs or other two-battery equipment, provides reliable isolation and charging from a single source.