Fogstar 16.kWh battery trips out but I don't know why. How to troubleshoot?

DIY
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1

I’ve had my MultiPlus-II 48/15000 and CerboGX working well with my Fogstar battery and solar panel array (with Enphase microinverters) for a few months.

However, in the last month there have been three times I’ve had the battery apparently reporting low voltage warnings/alarms and then the circuit breaker on it tripped so nothing went into or out of the battery until the breaker was reset.

Everything else kept working as normal, just the battery was absent from work.

Fogstar want to inspect the battery in case the breaker is faulty but since I am overseas that would prove awkward in view of my remote location.

Obviously I will arrange return of the battery if that proves necessary but I wonder if there are any troubleshooting tips I could use, working from the Victron side first?

I’d be grateful for any suggestions!

Thanks for reading.

2

On the vrm portal (Advanced tad) you can collect info/errors

If this is empty then you have to install Widgets.

You can export the info to a csv/xlsx file

3

Thank you, Fred.

Just a few minutes ago I got an email alert from the VRM saying there was a “low battery alarm”.

I logged on to the portal and the widget “System - Battery Voltage And Current” shows a dip in voltage to 51.55V - 53.10V.

I suppose my installer must have set the CerboGX to show the low voltage alarm at something like 51.55V.

What would cause a Warning to be issued after an Alarm has been triggered?

4

Low voltage alarms are system basic warning. Can be set up separately as well, but is usually basic system standard.

Which device is sending the low battery alarm?
The battery or the multiplus?

Does it happen around a certain SOC or charge state like absorption? or a certain load size? When/if you are feeding back to grid? Or when inverting?

5

Thank you, LX.

I’m a beginner - what is “bansysten”?

The alarms are sent by the Victron system, presumably a combination of the CerboGX and the MultiPlus.

As I said, the alarm was sounded a short while ago. At that time there was little to no sunshine so no generation, the battery should have been available to power any domestic loads in the house.

What I can see now in the Victron Connect app is that the battery is not fully charged (it says it is idle) and power is being drawn from the grid. The battery appears to be neither charging nor discharging - but it should be discharging (to power the house). The battery gets topped up to 100% overnight at cheap grid rates.

I suspect the circuit breaker has tripped again but I can’t verify that at this time.

6

Yes, the circuit breaker has tripped again!

In your experience, do circuit breakers on 48V batteries trip as a result of parameters set on other equipment (e.g.Cerbo GX) or do they have internal settings I’m not aware of?

7

Is what happens when I don’t check my spelling and autocorrect decided on nonsense. I apologise.

These are over current devices. So either it is undersized or there is something unexpected pulling the amps needed to trip it. Alternatively it is thermal tripping…

The alarm will have a device name before it for example 512 battery monitor or 256 multiplus.
By your explanation though it would be the inverter making the alarm as the battery would be low as it is not connected.

8

Thank you, LX.

It’s a big battery capable of very large in/out currents, far, far above what I would ever draw.

I’ve never seen the battery rise above 35 degrees C.

The alarms are labelled "VE.Bus System [276].

It’s beginning to look like the circuit breaker is too fragile. Bother, I’ll have to ship the whole thing back to base.

Oh, I still don’t know what “bansysten” should have said!

9

Took me a second too. Lol
Basic system…not even sure how…

10

Battery breaker tripping after low-voltage warnings usually points to a weak cell or BMS protection, not the Victron side. Grab the BMS logs before shipping it back.

11

Thank you, Richard.

Forgive me, how do I get the BMS logs, please?