Victron Energy SolidSwitch 104 Solid State DC Switch, 70V/4A, Digital Signal Control

Overview

The Victron Energy BMS800200104 is a SolidSwitch 104 solid-state DC switch for controlling DC loads up to 70 V and 4 A from a low-power digital control signal. It is made for low-current switching tasks in a boat DC system, such as controlling an alternator regulator in a Victron lithium installation, switching a small DC load, or expanding the number of chargers connected to a BMS ATC output.

It works with resistive, capacitive, and inductive loads, including contactor coils, when those loads stay within the specified limits. The operating input range is 8 to 70 V DC, the load turns on from a 3.3 V to 70 V remote input, and the minimum input current to switch on is 30 µA.

With an IP20 ABS housing and a 58 x 66 x 23 mm body, this unit belongs in a protected electrical space rather than an exposed cockpit or splash-prone engine room location. It is not reverse polarity protected and not short circuit proof, so wiring polarity and circuit protection need to be checked before power is applied.

Key features

• Switches DC loads up to 70 V and 4 A without using a traditional relay coil.
• Accepts a low-power digital control signal, with load off when the remote input is floating or below 3 V and load on from 3.3 V to 70 V.
• Works with resistive, capacitive, and inductive DC loads, including high-power contactor coils within the specified load limits.
• Very low control-side draw, about 0.04 Ah per month, which helps reduce standby drain in lithium BMS and alternator-control circuits.
• Useful for Victron lithium system tasks such as alternator regulator control or adding charger control points to a BMS ATC output.
• IP20 ABS housing in matt black with a 58 x 66 x 23 mm footprint for installation inside a protected DC distribution area.
• Not reverse polarity protected and not short circuit proof, so correct polarity, overcurrent protection, and careful commissioning are important.

Installation and setup

Mount the unit where it stays dry and protected, such as inside an electrical locker, battery system enclosure, or DC distribution panel with access for inspection. The IP20 rating is not for washdowns or salt spray, so the switch should not be treated as a deck-mounted component.

Before connecting the load, confirm the vessel voltage, the expected continuous current, and the type of load being switched. Capacitive and inductive loads have specific limits, so contactor coils, lights, and control circuits should be checked against the electrical design before energizing the switch.

Electrical and system integration

The SolidSwitch 104 is most useful where a BMS or control output can supply a small signal but should not carry the full load current. In a Victron lithium system, it can sit between a BMS control output and an alternator regulator or another controlled DC load, keeping standby draw low compared with a small relay.

It is not a replacement for a main battery switch, breaker, or high-current contactor. It is a control component for DC loads within its 70 V and 4 A rating, so the rest of the circuit should still use the correct cable sizing, overcurrent protection, and service disconnects for the boat.

Use cases on board

This switch is a good match for vessels using Victron lithium battery management, alternator control, or small controlled DC loads where standby amp-hour draw matters. It also makes sense on cruising boats, workboats, and fishing boats with control panels or automation circuits that need a small signal to control a separate DC load.