Best dual battery isolators
Researched by Deal.ai's shopping agent across stores on November 3, 2026. Prices below are today's.
Top pick: REDARC SBI12. It's the one to buy if you want a fit-and-forget isolator: solid-state, no moving contacts to weld shut, low standby draw, and an LED that tells you it's working. Rated 100A continuous, which covers most alternators on 4x4s, vans and boats.
Who the others suit:
- Blue Sea Add-A-Battery 7650 — boats and marine setups; a proper dual-circuit switch plus ACR, ignition protected.
- Stinger SGP35 — big-draw audio or winch systems that want a high-current relay.
- Vevor / MaySpare VSR kits — budget builds and ATVs/UTVs where a simple voltage-sensing relay and wiring kit is enough.
- WirthCo — plain, basic isolation on a small vehicle.
Match the isolator's amp rating to your alternator, and use cable sized for the full charging current.
The picks
- #1
REDARC Electronic Dual Battery Isolator (SBI12)
- Voltage: 12V DC
- Continuous current: 100A
- Standby current draw: low standby current draw
- Fault indication: LED indication of operation
- Surge protection: Fully surge protected
- Contact material: Silver contacts
