Is there any need for BMS / Charger / Inverter comms?

[dRdoS7]

Hi,

Interested in whether there is a need for communication between these devices.

I have no comms, and my system works.

As far as I can see the comms tells the other devices what the battery is doing so they can terminate charging or discharging.

Is there another function?

dRdoS7

 

[Philtao]

Usually the "comm" you mention is done via CANbus. The BMS is the equipment that is closest to the battery and knows best what is required to optimize and protect it. It instructs the chargers with charge voltage / current, and the inverter on max discharge voltage / current. A few situations that come to mind where this can be useful:

• reduce charge current when a cell voltage reaches lets say 3.45 v so that the balancer has enough time to balance before either the charger goes into float or the BMS shuts down the charge bus
• reduce the charge progressively as the cell temperature drops below 10°C, and stop charge entirely at 0°C

If all you need are on/off commands, you probably do not need that "comm", and the associated expense. Just use the BMS outputs (if it has more than 2) to remote command the chargers and inverters (either directly or with relays)

 

[jtvt]

Tying into the inverter and charger is useful if those devices don't handle an abrupt battery disconnect well.

The degree of communication probably depends on use case.