Troubleshooting intermittent low battery alarms on Victron systems with Freedom Won batteries

Q&A and troubleshooting
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1

Hi everyone,

We’re seeing an intermittent issue across multiple Victron ESS sites and are hoping someone may have experienced something similar.

The VRM portal is logging “VE.Bus System – Low battery: Alarm” events. However, when we review the historical data around the time of the alarm, we can’t find any evidence that the batteries were actually in a low battery condition.

Some observations:

  • The alarms are intermittent and clear automatically.
  • The sites continue operating normally before and after the alarm.
  • Battery SOC remains well above the configured minimum (one example never dropped below 40% SOC).
  • Battery voltage remains stable (approximately 51.5–53.5V on a 48V lithium system), with no significant voltage sag.
  • There were no grid outages or load shedding events at the time of the alarms.
  • The VE.Bus state appears normal, with the system cycling between Bulk, Inverting, and Passthru as expected.
  • PV production continues normally throughout the event.

We’ve now observed this on multiple sites with different hardware configurations:

Site 1

  • MultiPlus-II GX (v3.72)
  • MultiPlus-II 48/5000/70-50 (2623556)
  • Freedom Won Lite 5/4 battery (v6.8)
  • BlueSolar MPPT 150/60 (v1.74)

Site 2

  • Cerbo GX (v3.75)
  • MultiPlus-II 48/5000/70-50 (2623490)
  • Freedom Won battery (v6.8)
  • SmartSolar MPPT VE.Can 250/100 Rev2 (v3.10)

The common denominator appears to be the MultiPlus-II inverter/charger and Freedom Won battery, although the GX devices and MPPTs differ between the sites.

Has anyone else experienced these intermittent “Low battery” alarms where the battery voltage and SOC remain healthy?

We’re trying to determine whether this could be related to:

  • Freedom Won BMS communication,
  • VE.Bus firmware,
  • GX firmware,
  • ESS configuration,
  • Or another known issue.

If anyone has experienced this or has suggestions on additional logs or settings we should investigate, we’d really appreciate your advice.

Thanks in advance!

2

You sure it’s a Lite? They usually started at a 10/8.
5kWh was an etower.
One of those is pretty low power and it wouldn’t surprise me that you are getting those alarms with a single pack attached to a 5kVA inverter.

Edit. Ok Lite 2 starts at 10, the older models had a 5.

Check cell differences and see if you have any imbalances. Also what are your inverter settings? Did you follow the config guide?
Lite’s tend to behave, unless there is a config or install issue.

Maybe add some charts showing cell min/max, soc, battery voltage and current etc.

3

I don’t like their dynamic cut offs in ess personally.

Check the low battery warning Vs those setting and the load at the time.