Balmar Alternator Protection Module: Solid-State Defence Against Voltage Spikes and Load Dumps

Safeguard Your Alternator from Lithium BMS Disconnects, Switch Interruptions, and Inductive Surges

The Balmar Alternator Protection Module (APM) provides robust, solid-state protection for your alternator’s diodes and internal regulator. Designed to clamp high-energy voltage spikes and absorb sustained over-voltage conditions, the APM is essential for any charging system exposed to lithium battery BMS disconnects, battery switch interruptions, or surges from solenoids, combiners, and starter motors. Without protection, these events can instantly destroy an alternator—the APM eliminates that risk.

Engineered to meet stringent international standards, the APM mounts directly at the rear of the alternator between the B+ and B- terminals, ensuring the shortest possible path for surge diversion. Its compact, sealed design withstands harsh marine and automotive environments, including salt spray and fog, making it ideal for marine alternator protection, RV electrical systems, and off-grid power setups.

How the APM Protects Your Alternator

Voltage spikes occur when a load is suddenly removed from the alternator—such as a lithium battery’s BMS opening under full charge. The resulting load dump can generate spikes well above the alternator’s rating, puncturing diodes and frying regulators. The Balmar APM instantly clamps these transients, absorbing surge currents in excess of 200 A without failure. It also handles sustained over-voltage conditions, shunting excess energy away from sensitive electronics.

Unlike sacrificial devices that fail after a single event, the APM is designed for repeated surges. A green LED indicates active protection; if the module is ever compromised, a red LED and audible alarm alert you to replace it—providing clear, immediate status without guesswork.

Key Features

• Solid-state surge protection clamps voltage spikes and absorbs load-dump energy
• Protects against lithium BMS disconnects, battery switch interruptions, and inductive surges
• Surge absorption in excess of 200 A for repeated events without failure
• Visual and audible failure indication: green LED = protecting; red LED + beep = replace
• Compact, direct-mount design installs at alternator B+ and B- terminals
• Meets ISO 16750-2, ISO 7637-2, SAE J1171, and ASTM B117 for load dump, surge, ignition protection, and salt spray
• Compatible with all alternator brands and isolated or case-grounded configurations

Built for Harsh Environments

The APM’s sealed electronics and corrosion-resistant construction meet ASTM B117 salt spray/fog standards, ensuring reliable operation in coastal and marine applications. SAE J1171 ignition protection makes it safe for installation in engine rooms and other hazardous areas. Whether you’re powering a marine alternator on a bluewater cruiser, a 24V alternator in a mining vehicle, or a 48V alternator in an off-grid solar system, the APM delivers consistent, maintenance-free defence.

Simple Installation, Immediate Protection

Installation is straightforward: connect the red lead to the alternator’s B+ post and the black lead to B- (isolated ground alternators) or to a case mounting bolt (case ground alternators). The module’s small footprint fits neatly behind the alternator, requiring no additional brackets or wiring runs. Once connected, the APM begins protecting immediately—no configuration needed.

Optimised for 48 V systems, clamping high-energy transients to protect high-voltage alternators

Protect Your Investment Today

Don’t leave your alternator vulnerable to a single disconnect event. Install the Balmar Alternator Protection Module and gain peace of mind knowing your charging system is shielded against the most common and destructive electrical faults. Order now to safeguard your alternator and keep your power system running reliably.