Hi All,
Big shout out to REC and Tine for building this as a custom — it started as a specific request but I think it has broader relevance, which is why I'm sharing it here.
MODE 3 is a custom mode included in REC firmware 3.01. Prior to critical error induced BMS shutdown, the relay fires one and only one 400ms DC pulse which can be used to seamlessly connect an emergency battery via an ML-RBS 7700, keeping the system alive through what would otherwise be a hard cutoff. The pulse mimics the remote switch of the ML-RBS 7700 and activates the emergency battery automatically an instant before the LFP cuts out.
Cerbo GX users can also implement a Node-RED flow that manages the software transition to an emergency battery and associated settings — notably DVCC status and VE.Bus reset where necessary.
For anyone running critical installs, uninterrupted power is about safety and is a non-negotiable requirement for a vessel underway offshore or at night.
If interested in details feel free to contact me directly.
Hi Stefano, thanks for sharing this information.
I was looking for a kind of ATC signal to switch of my altenator before BMS shuts down the battery. You mention switching prior tot a critical error. I don't what you call a critical error ? See also my post https://ogm-energy.com/community/ogm-user-forum/topic/214569/protecting-altenator-with-atc-signal-when-main-relay-bms-switch-off . Maybe you can eleaborate on that ? Thx !
Hi Gerard,
for my purposes a critical error is defined as an error that causes the contactor to open.
Based on my research, here's what actually opens the contactor on the REC ABMS (vs. what's just a soft limit):
Contactor-opening conditions (hard shutdown):
HighCellVoltage — OV protectionLowVoltage — UV protectionHighDischargeCurrent / HighChargeCurrent — overcurrent/short circuitHighTemperature — overtemperatureInternalFailure — hardware fault
Soft-limit only (contactor stays closed):
LowChargeTemperature — charge current to 0A, no contactor openHighChargeTemperature — reduces charge currentLowTemperature — discharge limit only
I built a Node-RED failover flow that watches only the alarms that actually open the contactor, since triggering on soft limits would cause unnecessary failovers.
Note that this came from REC's published dbus alarm behavior and community sources, not a direct line from REC's own shutdown-trigger documentation. I would equally welcome info that confirm or dispute and correct my understanding.
That said, I have been told but can't quote any reference, that the ABMS would tell the WS500 to slow down and stop charging prior to an ABMS opening the cotactor. I am not sure about the ARCO and if it addresses your question, but you may be trying to solve a problem that you do not actually have. I hope it helps. Good luck.
