Blue Sea Systems Battery Isolators & Voltage Sensitive Relays
Blue Sea Systems Battery Isolators & Voltage Sensitive Relays
When it comes to advanced marine battery management, Blue Sea Systems specializes in battery isolators and automatic charging relays (also called ACRs, combiners, or voltage sensitive relays) designed to keep loads from discharging reserve battery systems. The brand has earned a dominant position in the marine electrical market, with Blue Sea Systems ACRs being easily the number one seller in this class of charge management devices. Whether you're managing dual battery banks on a fishing boat, sailboat, or RV, Blue Sea Systems offers intelligent solutions that eliminate the guesswork from battery isolators and voltage sensitive relays.
Industry-Leading ACR Technology
Blue Sea's automatic charging relays function as automatic switches that close when voltage on either battery rises to 13.2V-13.7V, indicating connection to a charge source, then share charging current with the other battery until voltage drops to 12.4-13.1V and the switch opens. This voltage-sensing intelligence ensures your starting battery remains protected while house loads draw power. The brand offers distinct product lines tailored to different applications and current requirements.
The SI-ACR (model 7610) is programmed to prevent cycling when combining battery banks, remaining closed if system voltage rises to at least 12.35V within ten seconds and 12.75V within 30 seconds. Start Isolation allows temporary isolation of house loads from the engine circuit during cranking to protect sensitive electronics from sags and spikes, making the SI-ACR ideal for vessels with modern electronics that are vulnerable to voltage fluctuations.
Heavy-Duty ML-ACR Series
For high-current applications, Blue Sea's 500-amp magnetic latching (bi-stable) ML-ACR relay automatically combines batteries during charging and isolates them when discharging and starting, with dual sensing on both battery banks. The magnetic latching technology is particularly efficient, as the ML-ACR draws very low current (less than 40mA to monitor terminal voltage) in the ON or OFF states due to continuous passive assistance from the magnet. These relays support high-output alternators and can be configured for both start isolation and engine isolation modes.
Why Blue Sea ACRs Outperform Traditional Isolators
Unlike battery isolators that use one-way electrical check valves called diodes, Blue Sea ACRs use a relay combined with voltage-sensing circuitry, making them more efficient because they create little heat and consume minimal charging energy. The ACR simplifies system design because chargers and regulators that work with a single battery bank will still work with multiple battery banks. This versatility makes Blue Sea voltage sensitive relays compatible with alternators, shore-power chargers, and solar panels without requiring specialized multi-output charging equipment.
Blue Sea Systems products feature ignition-protected, hermetically sealed contacts rated IP67 for marine environments, along with remote LED indicators that display relay status. Whether you need the 120-amp SI-ACR for mid-sized installations or the 500-amp ML-ACR for heavy-duty applications, these voltage sensitive relays deliver the reliability and performance that marine electrical systems demand.