Victron SolidSwitch 104 70V 4A Solid State Switch | BMS800200104

Description

The Victron SolidSwitch 104 is a compact solid-state DC switch that switches loads of up to 70 V and 4 A and is controlled by a low-power digital signal. The load can be resistive, capacitive or inductive, such as the coil of a high-power contactor.

What makes it different from an ordinary relay is its very low standby draw: Victron quotes about 0.04 Ah per month, compared with 10 Ah to 22 Ah per month for a small relay. That keeps the parasitic load in the range of the battery bank's own self-discharge, which matters on lithium systems that must not be slowly drained while idle.

Typical uses are controlling an external alternator regulator such as a Balmar or Mastervolt Alpha Pro on a Victron lithium system, switching a DC load such as a light, and adding more chargers to the ATC (allow-to-charge) output of a Victron BMS.

70 V / 4 A

Maximum switched load

8–70 V DC

Operating input voltage

0.04 Ah

Quoted draw per month

30 µA

Minimum input current to switch on

58×66×23 mm

ABS enclosure

IP20

Protection grade

Not Reverse Polarity Protected and Not Short-Circuit Proof

The SolidSwitch 104 has no reverse polarity protection and is not short-circuit proof. Check polarity carefully when wiring and protect the switched circuit with an appropriately rated fuse. Installation should be carried out by a qualified installer.

Observe the Capacitive and Inductive Load Limits

Maximum capacitive load depends on supply voltage: 1000 µF up to 15 V, 400 µF from 15 V to 30 V and 50 µF from 30 V to 70 V. Maximum inductive load depends on current: 1000 mH up to 1 A, 100 mH from 1 A to 2 A and 10 mH above 2 A.

Works With Victron BMS Charge Disconnect Outputs

For alternator charging, the charge disconnect output of a Victron BMS (smallBMS NG or VE.Bus BMS NG) is wired to the SolidSwitch remote input, so the alternator is switched off whenever the BMS gives a charger alarm.

Key Features

70 V / 4 A Solid-State Switching

Switches DC loads of up to 70 V and 4 A with no moving parts, and handles resistive, capacitive and inductive loads including contactor coils.

Ultra-Low Standby Draw

Draws about 0.04 Ah per month against 10 Ah to 22 Ah for a small relay, so control circuits do not add meaningful drain to an idle lithium battery bank.

Low-Power Digital Control

The remote input is off when floating or below 3 V and on between 3.3 V and 70 V, needing only 30 µA to switch on, so it can be driven directly from a BMS output.

Alternator Regulator Control

Switches the control of an external alternator regulator such as a Balmar or Mastervolt Alpha Pro, so the alternator stops charging when the BMS requires it.

Expands Charger Control

Increases the number of chargers that can be connected to the ATC output of a Victron BMS, so one allow-to-charge signal can switch several charge sources.

Compact, Wide-Range Design

A 58 × 66 × 23 mm ABS enclosure that operates from 8 V to 70 V, covering 12 V, 24 V and 48 V systems, from −20 °C to +50 °C.

Load and Control Limits

Load type

Condition

Maximum

Capacitive

Vbat up to 15 V

1000 µF

Capacitive

15 V < Vbat < 30 V

400 µF

Capacitive

30 V < Vbat < 70 V

50 µF

Inductive

Up to 1 A

1000 mH

Inductive

1 A < I < 2 A

100 mH

Inductive

More than 2 A

10 mH

Technical Specifications

Electrical

Operating input voltage range (Vbat)

8 – 70 V DC

Maximum load current

4 A

Remote input (Vin) – load off

Free-floating, or Vin below 3 V

Remote input (Vin) – load on

3.3 V < Vin < 70 V

Minimum input current to switch on

30 µA

Quoted standby draw

0.04 Ah per month

Protection features

Not reverse polarity protected; not short-circuit proof

General and Enclosure

Operating temperature

−20 °C to +50 °C (0 – 120 °F)

Humidity

Max 95 %, non-condensing

Protection grade

IP20

Material and colour

ABS, matt black

Dimensions (h × w × d)

58 × 66 × 23 mm

Part number (MPN)

BMS800200104

Frequently Asked Questions

Why use a SolidSwitch instead of a relay?

A small relay can draw 10 Ah to 22 Ah per month just to stay energised, while the SolidSwitch 104 draws about 0.04 Ah per month, which is likely below the self-discharge of the battery bank. That makes it a better fit for lithium systems that must avoid parasitic drain.

Is it protected against reverse polarity or short circuits?

No. The SolidSwitch 104 is not reverse polarity protected and not short-circuit proof, so wire it carefully and fuse the switched circuit.

What signal switches it on?

The load is off when the remote input is floating or below 3 V, and on when the input is between 3.3 V and 70 V. It needs a minimum of 30 µA to switch on.

Can it control an alternator?

Yes. It can control an external alternator regulator, such as a Balmar or Mastervolt Alpha Pro, on a Victron lithium system. The BMS charge disconnect output drives the SolidSwitch remote input, so the alternator is switched off on a BMS charger alarm.

Can it switch inductive loads such as a contactor coil?

Yes, within limits. Inductive loads up to 1 A can be up to 1000 mH, from 1 A to 2 A up to 100 mH, and above 2 A up to 10 mH. Check your contactor coil against these figures.

BTU Calculator

BTU & WATT Calculator

Room Dimensions

Length (in m):

Width (in m):

Height (in m):

Room Type

Living Room

Bedroom

Kitchen

Bathroom

Conservatory

Hallway

Glazing Type

Single Glazed

Double Glazed

Triple Glazed

External Walls

0 Wall

1 Wall

2 Walls

3 Walls

4 Walls

Insulation Level

Poor

Average

Good (New Build)

Calculate

Required Heating

0

Watts

0

BTUs