Every commercial lithium pack has a battery management system. The BMS does the non-negotiable work: cell-level voltage monitoring, over-current and over-temperature cut-off, charge control, and balancing the cells in a series string.
Telemetry is different. Telemetry is the BMS telling something outside the pack what it knows. Whether you specify it, and which protocol you specify, determines whether a degrading cell becomes a scheduled maintenance item or an unscheduled roadside failure.
The protocols, and what each is for
UART. A simple point-to-point serial link. Cheap, universally supported, and entirely adequate when the only thing that needs to read the BMS is a display or a diagnostic tool connected directly to the pack. It does not address multiple devices and it was never designed for electrically noisy environments.
Specify UART when the pack reports to a local display and nothing else.
CAN 2.0B. The automotive standard, and the right answer when the pack must talk to the vehicle. CAN is a multi-master bus with built-in arbitration and error detection, designed from the outset for the electrical noise of a vehicle harness. It is what a motor controller, a dashboard and a telematics unit expect to find.
Specify CAN when the battery is part of a vehicle system rather than a standalone block.
RS485. A differential, multi-drop bus that runs reliably over long cable distances and tolerates industrial noise. Where CAN is the vehicle answer, RS485 is the installation answer: several packs in a rack, a monitoring controller at the end of a long run, a building management system.
Specify RS485 for energy storage installations and multi-pack configurations.
Modbus. Strictly a protocol rather than a physical layer, usually carried over RS485. It matters because industrial monitoring equipment, inverters and SCADA systems speak it natively. If the pack must integrate with existing plant equipment, Modbus support is often the deciding factor.
What our range provides
Across the commercial catalogue you will see combinations including CAN 2.0B with RS485 telemetry, CAN 2.0B with RS485 and Modbus, and integrated smart BMS configurations on the simpler packs. Raw cell supply for B2B integrators ships without a BMS by design — the integrator fits their own.
The right specification depends entirely on what sits on the other end of the wire.
What telemetry actually buys a fleet
A BMS without telemetry protects the pack but tells you nothing until something has already gone wrong. With telemetry you can see:
- Per-cell voltage divergence. The single most useful early warning. Cells in a series string should track closely; one drifting consistently low is failing, usually weeks before it strands a vehicle.
- Temperature by sensor position. A hot spot in one region of the pack indicates a connection problem or a thermal path issue, not necessarily a cell problem.
- Cumulative cycle count and depth history. What the pack has actually experienced, which is what determines its remaining life — rather than what the duty cycle was assumed to be.
- Charge and discharge current profiles. Whether the vehicle is being operated and charged the way the specification assumed.
For a fleet of any size, the value is not in watching dashboards. It is in converting unplanned failures into planned maintenance, because a vehicle off the road unexpectedly costs considerably more than a battery.
A practical selection path
- Does the pack talk only to a local display? UART is sufficient.
- Is the pack part of a vehicle with a controller or telematics unit? Specify CAN 2.0B.
- Is it one of several packs in a fixed installation? Specify RS485.
- Must it integrate with existing industrial monitoring? Specify RS485 with Modbus.
- Are you integrating your own BMS? Specify raw cells and take responsibility for protection yourself.
The expensive mistake is specifying a pack with no usable telemetry for a fleet that will later need it. Retrofitting communication onto a sealed pack is not a practical option — the interface has to be designed in.
If you are specifying for a fleet and are not certain which protocol your telematics or charging infrastructure expects, send the details to the application engineering desk before the pack is built.