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Orion BMS 2 · Operations Guide

How the Orion BMS 2 actually behaves - current limits, state of charge, balancing, protection and failsafes - distilled from Ewert's operation manual into searchable topics. A companion for understanding and configuring the BMS; always follow the full manual and software manual for exact settings.

Cell V resolution
0.1 mV
Voltage sample
30 ms
Current sample
8 ms
Balancing
200 mA/cell
CAN interfaces
2
Failsafe modes
5
02

How the Orion BMS 2 works

The BMS is a monitor-and-instruct device: it measures, calculates limits, and tells external hardware what to do. It has no internal contactors, so the installed system must respect its outputs.

What it measures
  • Individual cell voltages (0.1 mV, ~30 ms)
  • Pack current via dual-range hall sensor (~8 ms)
  • Up to 8 on-board thermistors (800+ via expansion)
  • Total pack voltage (summed from cells)
  • Isolation to chassis, and the three power modes
What it controls
  • Charge / discharge current limits (CAN or 0–5 V)
  • Charge Enable, Discharge Enable, Charger Safety relays
  • Cell balancing (passive, in CHARGE mode)
  • Fan / thermal management
  • Multi-purpose outputs, J1772 & CHAdeMO charging
03

Topics

Search or filter, then tap a card to expand the key points. Each links back to its page in the full manual.

04

Failsafe modes

The BMS prioritises protecting the pack. These are the five failsafe modes it can enter - three keep operating in a degraded/latched way, two are non-operating.

Voltage failsafenon operating

Triggered when accurate cell/pack voltage is lost - an open tap wire, a cell reading below 0.09 V or above 5 V, or a remote-module comms loss. Both current limits gradually de-rate to 0 (so a vehicle can stop safely); relays turn off after the de-rate. Always investigate before clearing.

Current-sensor failsafedegraded

Triggered when the current sensor is unplugged, inaccurate, or absent. The BMS runs on voltage alone: internal-resistance, open-circuit-voltage, SOC and over-current protection are disabled or unreliable - but min/max cell-voltage protection still works.

Relay failsafelatching

Triggered when current still flows more than ~500 ms after an on/off output was told to turn off. All on/off outputs latch off until the fault is cleared or the unit is power-cycled.

12/24 V supply failsafedegraded

Triggered when input voltage stays below 8 V for more than 8 s. Enable outputs turn off and limits go to 0 (a contactor on the same supply may be unreliable). Recovers automatically when voltage returns.

Internal memory failsafenon operating

Triggered by damage to the profile memory. The BMS loads the factory-default profile with all inputs and outputs disabled to protect the pack, and sets a fault code.

05

Diagnostic trouble codes

Every Orion BMS 2 fault code, from Ewert's troubleshooting library. Search or filter, then click a code to open its detailed troubleshooting PDF on orionbms.com.

SourceCodes and detail pages are maintained by Ewert Energy at orionbms.com/troubleshooting - always check there for the latest guidance.
06

Documents & downloads

The full manual and the related interactive guides. Links open in a new tab.

SOFTWAREOrion BMS 2 UtilityConfigure & program the BMS · needs a CANdapterWindowsLinuxZIPBeta
PDFOperations manualThis guide (original PDF)DownloadLINKSoftware utility manualHow to program the BMSOpenGUIDEWiring & installationInteractive wiring guideOpenGUIDEQuick-start guide8-step interactive setupOpenGUIDEOrion BMS 2 guideInteractive system builderOpenLINKTroubleshooting (Ewert)Full fault-code listOpen