What do CAN bus and RS485 on a lithium forklift battery do, and does your charger need them?

Direct answer: They are data links, not power connections. CAN bus and RS485 let the battery’s BMS share information such as voltage, current, temperature, state of charge and allowed charge current with a charger, the truck or a monitoring tool. Whether your charger needs them depends on how it is designed to charge a lithium pack; a link only works if both sides use the same protocol. Confirm the protocol, connector and pin-out with Redway and the charger maker before ordering.

What the pages say: the 48V 280Ah, 48V 420Ah and 80V 400Ah tables list “Communication: RS485 / CAN bus / 4G”, a charger entry of “0.5C @ CC / CV” and a Forklift Cloud Monitoring System. Maximum continuous charge current is 150A (10–45 °C) on the 280Ah page and 200A on the 420Ah and 80V 400Ah pages. The pages do not publish the protocol, message list, baud rate or pin-out.

What each link is for. CAN bus is a two-wire network widely used in vehicles; several devices can share it, and it is often how a lithium BMS tells a charger what current it may accept and when to stop. RS485 is a robust serial link often used for monitoring and service tools. 4G sends data to the cloud for remote monitoring. A physical port is only the start: the battery and the charger must agree on the protocol (the meaning of each message), the speed and the wiring.

Does the charger need it? There are broadly two ways to charge a lithium forklift pack. A charger can follow a fixed lithium CC/CV profile set to the battery limits, with the BMS acting as a safety cut-off. Or the charger can take live instructions from the BMS over CAN and adjust current as the battery requests. Which approach is acceptable for a given Redway pack is a question for Redway; do not assume a lead-acid charger with a “lithium mode” is enough.

The truck side: some truck controllers read battery state of charge or fault signals so they can limit lift or travel. If your truck expects a signal from the original battery, ask whether the lithium pack can provide it, or whether the gauge and cut-out need setting up.

Questions to settle in writing: which protocol and version the BMS uses on CAN and on RS485; whether the battery must be on CAN for charging; which charger models Redway has tested with your exact pack; the connector and pin-out; what happens if communication is lost during a charge; and who supplies the cable. Our earlier post on what a forklift charger must support covers voltage and current limits.