Does a hub-1 error on a EasySolar 2 cause a Fogstar battery alarm to go off

Had this exact faff on my narrowboat last summer — Victron EasySolar 2 throwing a Hub-1 error and my Fogstar 15.5kWh screaming like a banshee every time it happened, and I still don't know which one's dobbing the other in first.

My suspicion is the Hub-1 error is a symptom rather than the cause — something upstream (grid disconnect, inverter hiccup, dodgy comms cable) triggers the Hub-1, the EasySolar briefly loses its head, and the Fogstar BMS interprets whatever voltage or current spike follows as a reason to throw a tantrum and sound the alarm.

What I noticed on mine:

• The alarm would go off within seconds of the Hub-1 appearing on the Victron GX screen
• Resetting the EasySolar cleared both faults
• It happened more when the battery was near the top of its charge — possible overvoltage blip when the inverter lost sync?

Checked all my VE.Direct and VE.Bus cables (classic narrowboat vibration loosening connectors), tightened everything up, and it happened less — but not zero.

Still not entirely convinced whether the Fogstar is reacting to something real or just getting spooked by the comms dropout. Anyone else running a Fogstar alongside a Victron EasySolar 2 seen this? Curious whether it's a known quirk or whether I need to be looking more carefully at my charge parameters in VictronConnect — wondering if my absorption voltage is set slightly too aggressive for the Fogstar's BMS tolerances.

Would love to know if anyone's actually cracked this one, because canal-side troubleshooting at 11pm in

@OffGridJulie the Hub-1 error is the EasySolar 2 losing communication between its internal components, which can cause the system to momentarily drop or spike current — and Fogstar BMSs are notoriously twitchy about sudden current irregularities, so it's almost certainly the Victron causing the battery alarm rather than the other way round.

Check your VE.Bus cable seating first — mine did exactly this in the motorhome until I reseated the internal ribbon connector. Also worth pulling the VRM logs to timestamp both events; if the Hub-1 precedes the Fogstar alarm by even a few seconds, that's your culprit confirmed.

Victron's ESS assistant update (v3.14+) reportedly calmed this behaviour down — worth flashing if you're on older firmware.

@OffGridJulie what you're likely seeing is a cascade rather than a direct cause. The Hub-1 fault interrupts the DVCC communication chain, which means the EasySolar temporarily loses its BMS-controlled charging profile. When that handshake drops, the Fogstar BMS sees voltage/current behaviour it doesn't recognise as "safe" — hence the alarm.

Worth checking your VE.Can or VE.Bus termination resistors first; a dodgy 120Ω terminator caused me similar grief with my static caravan setup before I found the culprit with a £15 multimeter.

Also pull the VictronConnect history — the timestamps on the Hub-1 errors and the Fogstar alarm events should tell you definitively whether it's simultaneous (cascade) or the battery alarming first (which would flip the diagnosis entirely and suggest the BMS is actually triggering the comms fault rather than reacting to it).

@OffGridJulie had this exact pantomime in my cabin setup — the Fogstar BMS isn't directly triggered by Hub-1, but when DVCC collapses the battery suddenly sees unregulated charge behaviour and that's what's tickling the alarm, not the error code itself.

Check your ESS Assistant version in VE.Configure — older firmware handles the comms dropout like a toddler handles bedtime. Update the EasySolar 2 firmware via VRM and make sure your Fogstar is on the latest BMS firmware too; those two talking nicely over VE.Can sorts about 80% of these phantom tantrums.

Also worth logging the exact alarm timestamp against your VRM data to confirm they're truly simultaneous or if there's a lag — that'll tell you whether it's cause or effect.

Saw the same circus in my static caravan — Fogstar alarm wasn't reacting to the Hub-1 itself, it was reacting to the sudden load dump when the EasySolar 2 threw its toys out, which the BMS reads as an overcurrent event and goes full drama queen about it.

Stuck a Cerbo GX in the loop eventually and could actually see the cascade @CliveBaker mentions in real time on VRM — the timeline makes it dead obvious it's sequential not simultaneous.