Blue Sea 11003 HD-Series Battery Switch with AFD

The Blue Sea Systems 11003 HD-Series Battery Switch with Alternator Field Disconnect is rated 500A continuous and accepts two 4/0 battery cables on M12 studs.

The alternator field disconnect is the reason to choose this over a plain HD-Series switch. Opening a battery switch while the alternator is charging can destroy the alternator's diodes, since the current has nowhere to go. AFD breaks the field circuit fractionally first, shutting the alternator down before the main contacts open.

This is an On/Off switch rather than a selector, so it isolates one bank rather than choosing between two. The 3003 covers the selector case with the same rating and the same AFD protection.

It accepts two 4/0 cables on M12 tin-plated copper studs, with extended length for multiple terminals. Tactile knob textures identify position by feel in a dark compartment, it mounts surface or rear-panel, and it is ignition protected and meets ABYC requirements. Explore more battery switches.

• AFD shuts the alternator down before the contacts open
• Switching off while charging can destroy the diodes
• On/Off isolation, not a bank selector
• Takes two 4/0 cables on M12 studs