6 MWh SRNE ASF48100U200-H 10kw.

[Zwy]

Can anyone honestly come up with a REAL reason to run comms aka bms connected to the inverter vs non comms?

My batteries cannot do comms and I haven't ever stood in front of my inverter saying "Damn I wish I could connect my batteries bms to my inverter"

The victron shunt has a dead accurate SOC that is what my system uses to know the SOC. BMS's are not accurate at ALL on SOC. So again is there a REAL reason? Any reason?

Is there a reason?

Yes, it is for those people who desire a challenge in life to get it working without failures.

I do not have a reason for inverter/BMS comms, I like life simple.

 

[Badbyte]

Only reason for me would be the ability to monitor, change settings and remote reset the systems no matter where in the world I happen to be.
All from one device with secured remote login capability NOT written by nor designed by chinese and other companies that are prone to include special gift embeded in some of their software....sigh... just my opinion btw.

 

[uslsml]

Is there a reason?

Yes, it is for those people who desire a challenge in life to get it working without failures.

I do not have a reason for inverter/BMS comms, I like life simple.

Using built-in BMS communication does have the benefit of less hardware (doesn't need a smart shunt or external agent reading SOC to get usable SOC-based inverter control). One poster also mentioned a situation where his BMS detected internal hardware fault and was able to quicker alert the inverter to stop charging.

 

[Zwy]

Using built-in BMS communication does have the benefit of less hardware (doesn't need a smart shunt or external agent reading SOC to get usable SOC-based inverter control). One poster also mentioned a situation where his BMS detected internal hardware fault and was able to quicker alert the inverter to stop charging.

BMS SOC is unreliable, that has been shown repeatably in these forums.

Using SA with a Smartshunt allows more accurate SOC monitoring, I know it is accurate because I run a Batrium BMS and it uses a shunt too for SOC monitoring and both shunts agree.

I would not want a BMS to shut down all charging if there was a hardware fault, I would want the BMS to shut down that battery both charging and discharging. I've had critical faults occur with the Batrium and it will trip the shunt trip ABB breaker basically shutting down my whole system unless the charge controllers can supply enough PV power to the DC bus. That has it's risks though.

If you are gone for the day and had not remotely checked on the system, it sucks when you walk in the door and find the system shut down and batteries that won't power thru the night. In winter, a cold house and furnace not running. For that reason, I am adding another battery with a JK BMS so at least one battery or the other is online.

 

[Zwy]

Only reason for me would be the ability to monitor, change settings and remote reset the systems no matter where in the world I happen to be.
All from one device with secured remote login capability NOT written by nor designed by chinese and other companies that are prone to include special gift embeded in some of their software....sigh... just my opinion btw.

SA and use a Smartshunt with it. You can check SOC, load, PV power and change inverter settings with SA from anywhere with web access.

 

[uslsml]

BMS SOC is unreliable, that has been shown repeatably in these forums.

Using SA with a Smartshunt allows more accurate SOC monitoring, I know it is accurate because I run a Batrium BMS and it uses a shunt too for SOC monitoring and both shunts agree.

I would not want a BMS to shut down all charging if there was a hardware fault, I would want the BMS to shut down that battery both charging and discharging. I've had critical faults occur with the Batrium and it will trip the shunt trip ABB breaker basically shutting down my whole system unless the charge controllers can supply enough PV power to the DC bus. That has it's risks though.

If you are gone for the day and had not remotely checked on the system, it sucks when you walk in the door and find the system shut down and batteries that won't power thru the night. In winter, a cold house and furnace not running. For that reason, I am adding another battery with a JK BMS so at least one battery or the other is online.

Using BMS comm between battery and inverter vs. using shunt/SA seems to be a one-or-the-other debate. Do the two options have to be mutually exclusive? The great thing is that we have options to choose from to get the tradeoff we want for our use cases and priorities. BMS SOC isn't the most accurate, but depending on the use case, it could be good enough to be usable (for my use case, it has been good enough).

Letting BMS error shut down the inverter or not also has its pros and cons. If the BMS errors are nuisance errors, that's detrimental. But if a BMS error prevents a fire, that's valuable. With the case I mentioned by another poster being glad that his BMS error shut down the inverter, I think it was a case where the internal hardware protection was compromised, so other than telling the inverter to stop charging, the BMS in that situation might not have been able to properly shut down the battery.

For people who prioritize safety and redundancy really high (rather shut down if anything doesn't look right anywhere), couldn't both approaches be combined? I haven't given this "combo approach" detailed thought, but it seems it could work.

 

[BuffaloTrace]

SA and use a Smartshunt with it. You can check SOC, load, PV power and change inverter settings with SA from anywhere with web access.

Yes to this. Need a shunt myself. The SOC reading is sometimes accurate with heavy useage on my solar hand cart, and other times WAY off due to such a small idle (30w) load or low end of day charging, that the bms is so far off, it can't be relied upon except as an individual cell voltage checking device and last ditch shut down device...which is annoying...but other than that open loop has been working great for me as well. I won't be changing this system, but any other system I build is going to use SA and it's accessories. Pretty awesome stuff, and nice to see it is compatible with SRNE and many others.