The Cyrix-Li-load is a microprocessor-controlled battery isolator and load relay built for lithium battery systems running at 24V or 48V. It connects and disconnects loads based on battery voltage, protecting lithium cells from over-discharge without needing manual intervention. It suits marine, vehicle and off-grid installations where load management matters.

Key features of this battery isolator switch

• Continuous current, rated at 230A, suitable for high-load DC circuits at 24V or 48V.
• Switching logic, microprocessor-controlled, responding to battery voltage thresholds rather than a simple relay timer.
• Battery chemistry, designed for lithium chemistries, with disconnect behaviour matched to Li-ion and LiFePO4 charge profiles.
• Low-voltage protection, disconnects loads automatically once voltage drops to a programmable low threshold, preventing deep discharge.
• Automatic reconnection, loads reconnect once the battery recovers to a safe voltage, with no manual reset needed.
• Weight, 0.3 kg, compact enough for confined spaces.

Product overview

The relay monitors battery voltage and switches a high-current contact to connect or isolate the load circuit. Unlike a standard combiner, it is built around the voltage windows specific to lithium batteries, so it will not reconnect a load prematurely after a low-voltage event, a common cause of repeated deep discharge in lithium systems.

At 230A the relay handles substantial DC loads: inverters, winches, bow thrusters and other high-draw appliances. Dual 24/48V compatibility means one part number covers both voltages. The microprocessor logic filters out brief voltage dips so transient loads do not cause unnecessary disconnections.

This unit belongs to Victron's Cyrix range, used across marine, motorhome and off-grid installations. It is not a BMS replacement. It works alongside a BMS to manage load-side disconnection based on voltage conditions.

Applications

• Load disconnection in 24V or 48V lithium systems on narrowboats, yachts and motorhomes.
• Off-grid cabins and mobile installations needing automatic load shedding.
• Commercial vehicle auxiliary power systems using lithium batteries.
• Any DC system where loads must be isolated to prevent lithium over-discharge.

What's in the box

• 1 x Cyrix-Li-load 24/48V-230A intelligent charge relay unit

Installation notes

Fit this by a qualified electrician or experienced marine or vehicle electrical engineer. Wire the unit in line with the load circuit, not the charge circuit. Size cabling for 230A continuous current and fit suitable fusing on the battery side. This unit is intended for lithium battery systems only; check voltage threshold compatibility before use with lead-acid. Follow applicable wiring regulations for marine and off-grid installations.