I’ve been looking at configuring my CERBO to send a signal based on SOC (when above 90% or something) - so I can put a relay inline with my alternators field excitement circuit to shut down the alternator when the batteries are getting close to full. Otherwise, the alternator triggers the BMS to stop the charge - which itself is hard on the alternator. Seems like the best fix would be to have the CERBO signal when we reach some threshold and then shut off the alternator.
However, when I try to set up the Relay #2 as a SOC triggered relay - I can’t - it only allows Manual or Temperature. Is there some fix for this or what am I doing wrong? (Relay #1 is auto-generator start/stop)
-pete
You could use the Large Firmware Version and use Node-Red to control the relay from SOC.
However, note that if you do not get the battery SOC to 100% from time to time to synchronise the SOC back to 100%, the SOC will drift and become less accurate. SOC is a derived parameter and not 100% accurate.
Your solution is treating the symptoms of the problem, not the cure, you should consider seeing if you can obtain a new lower voltage regulator for the alternator that does not trip the BMS as a minimum. Alternators are not ideal for this service as they do not have float functionality and a lower voltage regulator would still hold absorption for long periods, your proposal does prevent long term charging at absorption voltage. The best solution is to fit an external regulator or add a buffer battery and DC to DC charger.
Hi there, PW - thank you for the response.
I do get the batteries to 100% periodically either via solar or the generator. What I’m looking to do is protect the alternator from sudden BMS disconnect. I’ve got an Balmar Alternator Protector installed - but thought it would be good to shut it down as well when the charge level was approximately high (and let solar top it off). The alternator is regulated by a Balmar MX-614 on the LFP setting - which does have a separate charge/absorb/float (14.3v,13.6v,13.4v) settings that seem reasonably compatible with the batteries’ expectations (though REGO documentation is short). That said, I did notice that while testing the alternator at near 100% battery, the battery BMS signaled on the CAN bus that it shut down charging. I have 3 batteries - so it could have been just one that shut down - not sure of their level of coordination on that sort of thing. I’d rather not add another battery/dc-dc to the system if possible.
The system is 3x Renogy REGO 400ah LiFePo batteries with Victron solar / invertercharger / etc. CERBO is connected to batteries via RV-C CAN compatibility on the VE.Can port.
I certainly could install NodeRed (am familiar) - but it seems like a lot of overhead for a simple feature that is available on the other Relay. Does anyone know the thinking behind why one relay is much more capable than the other in the Venus small software?
Would love to hear any other thoughts / ideas of how best to configure this setup.