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

Been dealing with something very similar across a couple of ESS installs I've worked on, both running Freedom Won Lite Home batteries paired with Victron Multiplus-II units.

The intermittent low battery alarms in VRM are genuinely frustrating because they don't always correlate with actual state of charge. What I've found is that the alarm often triggers during high instantaneous load events — particularly when the EV charger ramps up — rather than reflecting a sustained low SOC condition.

A few things worth checking:

• VE.Bus assistant settings — specifically the "sustain voltage" and "dynamic cut-off" curve. If these aren't tuned to Freedom Won's actual discharge profile, the Multiplus can interpret a momentary voltage sag as a low battery condition
• CAN-bus communication — are the Freedom Won units actually talking to the CCGX/Cerbo properly? I've seen cases where the BMS data wasn't being read correctly and the system was falling back to voltage-based decisions rather than SOC-based ones
• DC cable sizing and connections — a poor connection creates resistive drop under load, which the Multiplus sees as low voltage even when the battery is perfectly healthy

On one of my sites, the culprit turned out to be a slightly undersized DC busbar causing voltage drop during EV charging peaks. Tightening up the cable spec sorted it almost entirely.

Freedom Won do publish recommended Victron integration settings in their documentation — worth cross-referencing your current config against that.

Anyone else seeing this pattern specifically during high-load transients rather than genuine low SOC situations? Curious whether it's more prevalent on certain firmware versions too.

Haven't used Freedom Won specifically but had something similar on my shepherd's hut build with a Victron SmartSolar and a pair of Fogstar Drift lithium batteries — turned out the BMS communication lag was causing the Cerbo GX to log phantom low voltage events that weren't actually happening at cell level.

Worth checking whether these alarms correlate with high load spikes rather than genuine SOC drops? On my setup, the kettle firing up would momentarily tank the reported voltage before the BMS could update properly.

@QJ_Builds — are you monitoring via VRM portal? The historical graphs are decent for spotting whether it's a genuine sustained dip or a millisecond spike triggering the threshold. Might also be worth adjusting the low voltage alarm threshold slightly if Freedom Won's default BMS reporting has any latency baked in.

Great thread, @QJ_Builds. I've seen exactly this on a Freedom Won Lite Home 10/8 paired with a Multiplus-II 48/3000. What caught me out was the CVL and CCL values in the DVCC settings not quite matching what Freedom Won recommend in their commissioning guide — even a small mismatch can cause the Multiplus to get confused about actual state of charge, especially under sudden load spikes.

Worth checking your VE.Bus to BMS assistant is configured correctly and that you're running the latest firmware on both the Cerbo and the battery BMS. Freedom Won pushed out an update last year that addressed some communication timing issues.

Also, are you monitoring via VRM? The historical SOC graphs can show whether the alarm events correlate with specific load patterns, which really helps narrow it down rather than just chasing your tail.

Worth checking the DVCC settings in VRM — specifically whether "Limit charge current" or the SVS/STS options are fighting with what the Freedom Won BMS is trying to do. Had a weird one in my shepherd's hut where the Victron kept second-guessing the external BMS signals and triggering phantom low voltage warnings.

Also double-check the CANbus termination resistor if you're running comms between the two. Loose or missing 120Ω terminator caused me no end of grief before I tracked it down.

@Holly1960 curious what firmware your Multiplus-II is on — there were some known quirks with ESS assistant versions that caused exactly this kind of ghost alarm before they patched it. Worth cross-referencing the Freedom Won commissioning doc too, they're pretty specific about the Victron config settings they want.

@Lefty already nabbed the DVCC angle, so I'll add — check your BMS assistant version in the Multiplus-II too, older firmware had a nasty habit of misreading the Freedom Won's CAN comms and throwing phantom low-cell warnings mid-discharge.

My shepherd's hut setup did something similar until I realised the Min cell voltage alarm threshold in VEConfigure was set stupidly low and the BMS was sending conflicting data — basically two alarm sources arguing with each other like a pub quiz team.

Also worth checking: is the VE.Bus BMS actually the active BMS or is it fighting with the Freedom Won's internal one? Double BMS syndrome is a real headache.

Both installs — same symptom?

If yes, probably a config template issue rather than hardware fault.