Ampper Side-Post Knife Blade Battery Disconnect Switch 12V–24V — Brass, 200A Continuous

Ampper's side post knife-blade battery disconnect is a compact, brass master switch that cuts DC 12V–24V power fast to prevent parasitic drain and isolate GM-style side post batteries.

This compact switch mounts to GM-compatible side post batteries with a 3/8" hole and provides a clear on/off knife-blade action for instantly disconnecting the battery. Built from solid brass for corrosion resistance and supplied as a complete kit, it’s sized for cars, boats, RVs, ATVs and other 12–24V electrical systems where you need a reliable, serviceable cutoff that withstands heavy currents.

How does this switch stop battery drain when a vehicle sits unused?

The knife-blade design gives a true physical break in the battery circuit. Lifting the blade interrupts all connected loads so accessories and control modules can’t draw power while the vehicle or boat is parked.

• Two-position on/off blade provides a visible and tactile disconnect.
• Recommended mounting on the negative side to isolate the system.
• Designed for GM-style side post terminals with a 3/8" hole.
• Comes with short and long terminal bolts, spacers and washers for a secure fit.

Will it handle starting currents and heavy loads?

The Ampper switch is rated for continuous 200A and a momentary 600A surge at 12V, giving it the capacity to tolerate cranking and larger accessory draws without damage. Solid brass construction helps manage heat and resists corrosion in marine and automotive environments.

• 200A continuous rating for sustained loads.
• 600A momentary rating to accept engine starter surges at 12V.
• Solid brass terminals reduce resistance and chemical corrosion.
• Knife-blade design minimizes arcing during operation.

How simple is installation and what hardware is included?

Installation is straightforward for anyone familiar with side-post battery hardware. The kit includes multiple bolt lengths and mounting washers so you can fit common GM-style posts without fabricating extra parts.

• Includes one switch, one short bolt and two pairs of 3/8" terminal bolts (short and long).
• Two spacers and two washers are supplied to ensure proper spacing and tight connections.
• Recommended for batteries with a 3/8" side-post hole only.
• Can be used standalone or ganged with other switches for system control.

Is this safe for marine use and outdoor exposure?

Yes — the brass body and hardware resist rust and corrosion better than many plated components, making the switch suitable for boats and other moisture-prone settings when installed correctly. It’s meant to be mounted securely and checked periodically for tightness and cleanliness.

• Solid brass material reduces corrosion and maintains conductivity.
• Knife-blade removal provides a clear open circuit for safety and storage.
• Check connections regularly in salted or wet environments.
• Compact footprint fits tight battery compartments and trays.

Who is this for: mechanics, boat owners, RV and off-road vehicle enthusiasts, fleet managers and anyone who needs a dependable way to isolate a GM-style side post battery. If you want a straightforward, durable master cutoff that tolerates starting surges and eliminates parasitic drain while offering easy serviceability, this Ampper kit is engineered for those uses.