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alan asked

Synchronize VE.Bus SOC with battery? Select on loss of communication source for genset

Synchronize VE.Bus SOC with battery

Has this item been rolled into dvcc? After some digging here it seems its been removed yet its still in the manual. The last mention of it in the changelog is in the v2.02 – 30 January 2017 Venus Os

Are you guys working on an update to the manual to remove redundant settings to avoid confusion?


loss of communication source for genset

I have a few systems I setup and support with auto start gensets, after a couple of weeks of bad weather one went into LVD during a sustained load at a low SOC. Voltage start timing settings were a bit too long to catch the voltage crash. LA batteries.

I had set start on loss of communication as a third fail safe to start the genset, and had the BMV as the source for genset SOC. However the genset didn't start as the BMV was still active yet the multi had shutdown. I had assumed that it would start on loss of comms to anything on the VE.bus. After rereading the manual, it's loss of communication to the SOC source.

Normally I disable the battery monitor in the multi to avoid the user accidentally changing the source.

I have now reenabled the monitor in the multi, which seems to be tracking the BMV and set the genset SOC source to the multi.

However Synchronize VE.Bus SOC with battery is completely missing so the only indication the SOC is being read by the BMV to the system is that its the same as the BMV.


Seems a rather complicated method, could we simply have this changed so we could select the loss of communication source?


This now raised another question, when performing remote configs through the portal the multi/quattro drops communications to the venus device for a moment. Will this cause a genset start?


BMV Battery MonitorVenus OSCCGX Color ControlGeneratorSOC
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JohnC avatar image
JohnC answered ·

Hi @Alan

I'm rusty on this, but I think that 'Synchronize..' function changed with a (VE.Bus?) firmware upgrade. It was only an advisory anyway. So even though you mightn't see it now, it may still be relevant to those on older firmware. So don't be too harsh on the manual maintainers..

Where the SOC is coming from is shown in the GX's 'System Setup'.

But you don't actually say where you auto-start the genny from, as there's options for that. And a "shutdown" Multi seems like a serious issue, as it's the gizmo that accepts the genny usually.

If you're worried about 'loss of comms' between the kit then you need to determine why. I find it ultra-reliable normally, but I only use wires. Wifi for internet.

Consider setting alarm rules in VRM, so you'll get emailed from the server if something is amiss.



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alan avatar image alan commented ·

The multi will restart a couple of seconds after it gets AC from the genset and the relay engages. I have seen this many times.


the system SOC source is set to the bmv. I have now set the SOC source for genset start to the multi and it seems to be receiving the SOC from the BMV.

Genset starts are set by SOC first, at the customer’s requested settings. Then battery voltage as a second fail safe. (This the start timing was a little bit too long, combined with a moderate LVD in the multi to reduce battery damage from low discharge.) Then loss of communication was a 3rd fail safe so that the genset kicked in and restarted the multi/system and allow the fronius PV to help bring the batteries up faster than just the MPPT alone.

I was thinking if you could simply select the loss of comms device then you don’t have to enable the battery monitor in the multi and hope it is in sync with the BMV (for accuracy reasons).


Having two different SOC sources for two different functions just seems overly complicated

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JohnC avatar image JohnC ♦ alan commented ·

I'm sorry, I can't follow this. Maybe someone else?..

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alan avatar image alan JohnC ♦ commented ·

See, for something simple its rather complicated.

For the system you select a soc source

For the genset start/stop you also select a soc source, this can be different to the system SOC source.


If you select the BMV for the genset start/stop source, then all the options work well except the loss of comms, if the multi shuts down due to hitting LVD, the bmv will still be running so the venus device hasn't lost comms and wont kick the genset in to bring the system back up.

So to get this working, the battery monitor in the multi needs to be enabled, then the genset start/stop source needs to be set to the multi. Which is relying on it being constantly synced to the BMV to be accurate, then when/if the multi goes in LVD the venus kicks the genet in as it lost comms.



It would be simpler (maybe depending on the code etc..) to be just able to select a loss of comms device.

Ie, if comms lost to multi/bmv/mppt/whatever start genset

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JohnC avatar image JohnC ♦ alan commented ·

@Alan

I guess it's the complexity in your method that has me confused.

Why couldn't you just start the genny from the Multi (Assistant) before it shuts down? Paralleled in to the GX start signal.

Then a 4th level - have VRM email the client when the genny doesn't start? He might even forget to fuel it, hey..



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