Victron miniBMS /smallBMS
Victron miniBMS /smallBMS
Pre-alarm output, load/charge disconnect, 8-70V DC, 106x42x23mm
Highlights:M8 Connectors: Quick-connect M8 circular connectors for easy integration with Victron Lithium Smart batteries,Screw Terminal Block: 7-pin green screw terminal block for load disconnect, charging, and pre-alarm wiring,Status LEDs: Visual indicators for Load ON status and Temperature or Overvoltage protection warnings,Remote Control: Remote L and H terminals for external system on/off control,Pre-alarm Output: Terminal providing an early warning signal before the BMS disconnects loads.

Wiring diagram illustrating the integration of a miniBMS with a 12V lithium battery, MPPT solar controller, and Smart BatteryProtect in a DC off-grid configuration.
Application example for marine or automotive systems, showing the miniBMS controlling an alternator and charging system via a Cyrix-Li-ct relay.
Key features: Operating voltage range from 8 to 70 VDC, Integrated pre-alarm output signal, Remote on/off control terminals, Durable matt black ABS enclosure, IP20 protection rating.
Technical dimensional drawing providing detailed specifications for the smallBMS enclosure, including its 107mm total length and mounting hole positions. 
DESCRIPTION
Victron smallBMS NG: Advanced Battery Management for Victron Smart Lithium Systems
Precision Protection for 12V, 24V, and 48V LiFePO4 Battery Banks
The Victron smallBMS NG (BMS400100000) is a compact, next-generation battery management system engineered to safeguard Victron Smart LiFePO4 batteries in off-grid, marine, and mobile applications. Replacing the earlier miniBMS, this unit delivers reliable cell-level monitoring and control without the complexity or cost of a full VE.Bus BMS. It is purpose-built for systems where a VE.Bus interface is not required, making it an ideal match for standalone inverters, DC-DC converters, and solar charge controllers.
Designed for seamless integration with Victron’s M8 circular connector Smart Lithium batteries, the smallBMS NG actively prevents deep discharge, overcharge, and temperature extremes. Its three independent outputs—Load Disconnect, Charge Disconnect, and Pre-Alarm—provide layered protection that extends battery service life and enhances system safety. Whether you are building a 12V caravan solar setup, a 24V marine power system, or a 48V off-grid energy storage solution, this BMS ensures your lithium investment remains protected under all operating conditions.
Three-Stage Protection Architecture
The smallBMS NG continuously monitors individual cell voltages and battery temperature via the Victron battery’s internal BMS communication. When parameters approach critical thresholds, it initiates a sequenced response:
- Load Disconnect Output: Normally high (Vbat – 0.1V), this output transitions to free floating when any cell drops below the under-voltage threshold (default 2.8V/cell, adjustable 2.6–2.8V). With a 1A source current limit, it can directly drive a high-current relay, contactor, or the remote on/off input of a Victron BatteryProtect, inverter, or DC-DC converter. This prevents irreversible cell damage from over-discharge.
- Pre-Alarm Output: Provides an early warning signal before load disconnect occurs. Normally free floating, it activates (Vbat – 0.1V, 1A max) when cell voltage falls to the pre-alarm threshold (default 3.1V/cell, adjustable 2.85–3.15V). A minimum 30-second delay before load disconnect gives systems time to shed non-critical loads or start a generator, avoiding unexpected shutdowns.
- Charge Disconnect Output: Normally high (Vbat – 0.6V), this output goes free floating to signal an imminent cell over-voltage or over/under-temperature condition. With a 10mA source current limit and short-circuit protection, it is designed to control the remote on/off of chargers, Cyrix-Li-Charge relays, or Cyrix-Li-ct Battery Combiners. This ensures charging stops before cells exceed safe voltage or temperature limits.
Flexible System On/Off Control
The Remote L and H terminals allow straightforward system-wide on/off switching. Three control modes are supported: bridging L and H, pulling L to battery negative (<3.5V), or applying a high signal to H (2.9V to Vbat). This flexibility simplifies integration with external switches, BMS panels, or automated controllers, enabling a single point of control for both loads and chargers.
Built for Harsh Environments
Housed in a matt black ABS enclosure rated IP20, the smallBMS NG measures just 106 x 42 x 23 mm and weighs 0.1 kg. It operates across a wide temperature range of -20 to +50°C and tolerates up to 95% non-condensing humidity. The compact footprint allows installation in tight electrical compartments typical of caravans, boats, and equipment cabinets. Status LEDs provide immediate visual feedback: a blue Load ON indicator confirms active load output, while a red Temp or OVP LED warns of charge disconnect due to temperature or over-voltage events.
Why Choose the Victron smallBMS NG?
- Direct compatibility with Victron Smart LiFePO4 batteries featuring M8 circular connectors—no additional interfaces required.
- Wide operating voltage range of 8–70 VDC supports 12V, 24V, and 48V nominal systems from a single model.
- Ultra-low power consumption: typically 2.2 mA when remote on, minimising parasitic drain on the battery bank.
- Pre-alarm functionality reduces the risk of sudden system shutdowns by providing advance warning of low cell voltage.
- Automotive-grade compliance to UN/ECE-R10 Rev.4, plus safety and EMC standards (EN 60950, EN 61000-6-3, EN 55014-1, EN 61000-6-2, EN 61000-6-1, EN 55014-2), ensuring reliable operation in vehicle and marine environments.
Applications
The smallBMS NG is the preferred battery management solution for Victron lithium systems where a VE.Bus MultiPlus or Quattro inverter/charger is not used. Typical installations include:
- Caravans and camper trailers with standalone inverters and MPPT solar controllers.
- Marine electrical systems using alternator charging via Cyrix-Li-ct relays.
- Remote off-grid cabins and tiny homes with DC-only or non-VE.Bus AC systems.
- Portable power packs and mobile workstation setups.
By offloading critical protection functions to a dedicated BMS, you reduce the risk of cell damage, improve system reliability, and simplify wiring compared to generic or multi-brand solutions. The smallBMS NG is not suitable for use with VE.Bus inverter/chargers; for those applications, consider the VE.Bus BMS.
Protect Your Lithium Investment
Equip your Victron Smart Lithium battery bank with the smallBMS NG and gain confidence that your cells are monitored and protected around the clock. Order the Victron smallBMS NG today and build a safer, longer-lasting energy system for your next adventure or off-grid project.
SPECIFICATIONS
Specifications
| Product | smallBMS with pre-alarm BMS400100000 |
| Operating voltage (Vbat) | 8 – 70 VDC |
| Power supply cable and fuse (not supplied) | Recommended fuse size 0.3 A - 2.5 A, dependent on devices connected to Load disconnect and pre-alarm output |
| Current consumption, remote on | 2.2 mA (excluding Load and Charge disconnect output current) |
| Current consumption, low cell voltage | 1.2 mA |
| Current consumption, remote off | 1.2 mA |
| Load disconnect output | Normally high (Vbat – 0.1 V) Source current limit: 1A (not short circuit protected) Sink current: 0A (output free floating) |
| Charge disconnect output | Normally high (Vbat –0.6 V) Source current limit: 10mA (short circuit protected) Sink current: 0A (output free floating) |
| Pre-alarm output | Normally free floating In case of alarm: output voltage Vbat -0.1 V Maximum output current: 1A (not short circuit protected) |
| Remote on/off | Remote L and Remote H Use modes: 1. ON when the L and H terminal are interconnected 2. ON when the L terminal is pulled to battery minus (V <3.5 V) 3. ON when the H terminal is high (2.9 V <VH <Vbat) 4. OFF in all other conditions |
| GENERAL | |
| Operating temperature range | -20 to +50 °C (0 – 120 °F) |
| Humidity | Max. 95 % (non-condensing) |
| Protection grade | IP20 |
| ENCLOSURE | |
| Material and colour | ABS, matt black |
| Weight | 0.1 kg |
| Dimensions (h x w x d) | 106 x 42 x 23 mm |
| STANDARDS | |
| Safety | EN 60950 |
| Emission | EN 61000-6-3, EN 55014-1 |
| Immunity | EN 61000-6-2, EN 61000-6-1, EN 55014-2 |
| Automotive | Regulation UN/ECE-R10 Rev.4 |
| SKU: | VIC-BMS400100000 |
| Barcode: | 8719076043485 |
| Model #: | BMS400100000 |
| MPN: | BMS400100000 |
WARRANTY
Victron Energy Limited Warranty Policy
Direct Customers
Victron Energy provides the following warranty to any direct customer (OEM, distributor or dealer) in relation to any products that Victron Energy has directly sold to the direct customer. This warranty is not an end-user warranty between Victron Energy and an end-user, and end-users shall not have any rights or remedies under this limited warranty towards Victron Energy directly. The direct customer shall, in turn, ensure that the end-user is provided with a warranty identical to this warranty, subject to applicable local mandatory law.
End-Users
Victron Energy may also provide a warranty directly to end-users, in which case the below warranty conditions equally apply to such warranty. In that case, end-users shall claim their warranty at their place of purchase or through the original direct customer of Victron, which can be found through the support section on Victron’s website https://www.victronenergy.com/support. Hence, the direct customer shall on behalf of Victron Energy deal with any warranty claims made under any warranty that Victron Energy may provide directly to end-users. This support section on Victron’s website https://www.victronenergy.com/support will provide further guidance on the procedure for end-users to make a claim under this limited warranty.
If the end-user is a consumer – a natural person who is acting for purposes which are outside that person's trade, business, craft or profession – the following applies. The rights and remedies granted to the consumer under this limited warranty are without prejudice to the consumer’s statutory rights. Furthermore, the consumer is entitled by law to remedies from the seller free of charge in the event of a lack of conformity of the goods (such as repair, replacement, price reduction or rescission), which remedies are not affected by this limited warranty.
Warranty
Victron Energy warrants its products to be free from defects in workmanship and materials for a period of 5 years from the date of purchase by the original end-user, with a maximum of 66 months from the Victron Energy invoice date. Exceptions on this are: lead-acid batteries: 2 years from date of purchase by the original end-user, with a maximum of 30 months from the Victron Energy invoice date, Lithium batteries: 3 years from date of purchase by the original end-user, with a maximum of 42 months from the Victron Energy invoice date. In addition to this, proof of correct battery usage is required when making a battery warranty claim.
For a 10% surcharge on the current net price for products that came with a 5-year warranty, an additional 5 years of warranty can be purchased by Victron’s direct customers, bringing the total warranty to 10 years. Warranty extensions need to be applied for ultimately one year before the expiration of the original term. Victron may ask proof that the product was still functional at the time of purchase of the extended warranty.
During the warranty period, Victron Energy will, at its discretion, repair, replace or (partly) credit the defective product free of charge. The warranty does not include performing or reimbursing de‐installation, transportation, and re‐installation.
This warranty will be considered void if the unit has suffered any physical damage or alteration, either internally or externally, and does not cover damages arising from improper use like:
- Reversed battery polarity.
- Inadequate connection.
- Mechanical shock or deformation.
- Contact with liquid or oxidation by condensation.
- Use in an inappropriate environment (dust, corrosive vapour, humidity, high temperature, biological infestation, etc.).
- Breakage or damage due to lightning.
- Connection terminals and screws destroyed or other damages, like overheating, due to insufficient tightening.
- For any electronic breakage except due to lightning (reverse polarity, over‐voltage due to external cause), the state of the internal control diode and/or the input/output X and Y capacitors determine the warranty.
This warranty will not apply where the product has been misused, neglected, improperly installed, or repaired by anyone other than Victron Energy or one of its authorized Repair Centres. In order to qualify for the warranty, the product must not be disassembled or modified.
This warranty and our warranty obligations thereunder (repair, replacement or credit) are the direct customer’s and, if applicable, the end-user’s sole rights and remedies and our sole obligations with respect to any defective and/or non-conforming product or breach of warranty and is subject to and without prejudice to the limitations of liability in this warranty.
Victron Energy shall not be liable for damages, whether direct, incidental, special, or consequential, even caused by negligence or fault.
As a product requires service, it must be brought back to the place of purchase. In case no contact can be made with the merchant, or if he is either unable or not allowed to provide service, direct contact should be made with Victron Energy through the support section on Victron’s website.
In case Victron Energy replaces a product, it will own the replaced product. Victron Energy owns all parts removed from repaired products. Victron Energy uses new or reconditioned parts made by various manufacturers when performing warranty repairs or building replacement products.
If Victron Energy repairs or replaces a part of a product, its warranty term is not extended: the warranty will apply for the remaining term of the original warranty term. For example, if Victron Energy replaces a product with a 5-year warranty after 3 years, the warranty of this product will apply for another 2 years, with a minimum of 6 months.
All remedies and the measure for damages are limited to the above. Victron Energy shall in no event be liable for consequential, incidental, contingent or special damages, even if having been advised of the probability of such damages.
The foregoing limited warranty provided by Victron Energy is in lieu of any other warranties, express or implied arising by law, course of dealing, course of performance, usage of trade or otherwise, of any kind whatsoever including, without limitation, warranties of merchantability or fitness for a particular purpose, with respect to any product. The above is without prejudice to the arrangement for consumers detailed above.
Life Support Policy
As a general policy, Victron Energy does not recommend the use of any of its products in life support applications where failure or malfunction of Victron Energy's product can be reasonably expected to cause the failure of the life support device or to significantly affect its safety or effectiveness. Victron Energy does not recommend the use of any of its products in direct patient care. Victron Energy will not knowingly sell its products for use in such applications unless it receives in writing assurances satisfactory to Victron Energy that the risks of injury or damage have been minimized, the customer assumes all such risks, and the liability of Victron Energy is adequately protected under the circumstances.
Warranty on repairs for products outside their warranty period
The warranty period on products that are outside their warranty period and have been repaired by Victron Energy or one of the Victron Energy Repair centres is six (6) months from delivery. The same applies to spare parts and circuit boards that have been supplied or repaired by Victron Energy.
Transport
It is the responsibility of the sender to sufficiently package these products. The transport must be organized in a way to avoid any damage, especially when a single unit or heavy unit is sent.
Severability
If a part of the terms and conditions of this warranty is held invalid, void or unenforceable due to any particular national or international legislation, it shall not affect other parts of the terms and conditions of this warranty.
Applicable law
This warranty is exclusively governed by the laws of the Netherlands, to the exclusion of the UN Convention on Contracts for the International Sale of Goods.
Contact details
Victron Energy B.V. | De Paal 35, 1351 JG Almere, The Netherlands | https://www.victronenergy.com/support



















































