Blue Sea Systems DC Analog Ammeter 0-100A with Shunt

The Blue Sea Systems DC Analog Ammeter gives a classic, traditional dial display of DC current from 0 to 100A, sensing current through an included external shunt rather than a clip-on coil — the standard approach for accurate DC current measurement on a marine electrical system.

Key features

• 0-100A DC display range on a 2-3/4in dial face
• Simple 4-wire connection from the included external shunt
• Meter senses and powers itself entirely from the shunt connection
• Backlit face with separate 12V and 24V DC backlight wiring connections

The shunt installs in the negative circuit between the battery and its load, and the meter reads the small voltage drop across it to calculate current — this is the standard, accurate method for DC ammeters, quite different from how AC current transformers work. Because the backlight wiring is separate from the sensing circuit, this same meter works cleanly on either a 12V or 24V system by simply choosing the correct backlight leads for the installation.

This is a practical, no-frills way to monitor battery charge or discharge current on a boat that doesn't need the programmability of a digital multimeter — a windlass, winch, or inverter circuit are common places to add this kind of at-a-glance current monitoring.

Route the shunt's sense leads carefully and avoid using them as current-carrying connections — their integrity is absolutely critical to accurate readings, and using them to carry load current instead of just sensing current will introduce measurement error into every reading the meter subsequently displays.