Repeatedly getting "No-data” alarms

Been running a similar setup out here for just over three years now — pair of Multiplus II 5000s in parallel, two Victron SmartSolar 250/100s, Cerbo GX, and a bank of Fogstar Drift 48V cells. Mostly solid, but lately I'm getting these intermittent "No-data" alarms on the Cerbo and it's doing my head in.

It seems to happen overnight mostly, when the system's quiet and the EV's not pulling anything. The VRM dashboard just shows gaps in the logging — sometimes 20 minutes, sometimes a couple of hours. No obvious pattern.

A few things I've already checked:

• LAN cable from Cerbo to router is fine (swapped it out)
• VRM interval is set to 1 minute
• Firmware on Cerbo is up to date

What I haven't done yet is look closely at whether the MPPT comms are dropping on the VE.Direct side. Someone on another thread mentioned a dodgy VE.Direct cable can cause the Cerbo to essentially lose its mind and drop logging altogether, even though the inverters keep running fine.

Anyone else seen this with a parallel Multiplus setup specifically? I'm wondering if the master/slave comms introduce extra load on the Cerbo that makes it more susceptible to going quiet when there's low activity.

Also curious whether anyone's running a Raspberry Pi alongside their Cerbo as a backup logger — starting to think it might be worth it for peace of mind. Would be good to know if the data gaps are actually causing any real-world issues or if it's more of an annoyance than a problem.

@MuddyTrekker had almost identical grief with my Cerbo last winter at the cabin — turned out the VE.Can termination resistors were the culprit. One end of the bus wasn't terminated properly and under cold conditions the resistance drifted enough to cause intermittent dropouts. Classic "works fine in summer, goes daft in January" scenario.

Worth checking both ends of your VE.Can chain have their 120Ω terminators fitted correctly. Victron's own documentation is surprisingly quiet about this being a cold-weather failure point.

Also — what firmware are you running on the Cerbo? There was a particularly troublesome build a while back that caused spurious no-data alarms on parallel Multiplus setups specifically. Dropping back a version sorted it for several people I know.

@MuddyTrekker this happened to me on the narrowboat last spring — drove me absolutely round the bend for a fortnight. Turned out my VE.Direct cables were the culprits; one had a slightly dodgy TX pin that only played up when the bilge temperature dropped overnight. Classic.

Worth checking:

• VE.Direct cable integrity on each SmartSolar individually
• Cerbo GX firmware — I was two versions behind and the no-data alarms were practically a feature at that point
• Pull each device off the network one at a time to isolate which unit's actually misbehaving

The Cerbo logs will tell you which device triggered the alarm if you dig into the Remote Console → Device List. Often people chase the wrong rabbit entirely.

Given you've got two SmartSolars in parallel, my money's on one of them rather than the Multiplus IIs.

@MuddyTrekker worth checking something that catches people out with parallel Multiplus IIs specifically — the VE.Bus cable between the two units. If that's marginal (dodgy crimp, slightly wrong gauge, or just a cheap generic cable rather than genuine Victron), the Cerbo can intermittently lose comms with one or both units under load, triggering exactly these no-data alarms.

Also, on the Cerbo itself: what firmware are you running? There was a particularly nasty bug around v2.8x that caused spurious alarms with parallel inverter configurations. Worth checking Venus OS version and updating if you're behind.

My own setup threw similar wobblies until I replaced a suspiciously flimsy third-party RJ45 on the VE.Bus network — embarrassingly simple fix after three weeks of head-scratching. Sometimes it really is the £2 connector causing £2,000 worth of stress.

@MuddyTrekker my garden office Cerbo pulled the same stunt until I realised the MicroSD card was full of logged data — cleared it down and the "No-data" ghosts vanished like they'd never existed.

@MuddyTrekker had this exact drama with my garden office setup — turned out my Cerbo's ethernet cable had developed a dodgy crimp at the connector end, so it was dropping the network connection just long enough to trigger the alarm before reconnecting like nothing happened, absolute little gremlin 🔌

Worth ruling out by temporarily switching to WiFi (or vice versa) just to see if the alarms stop — if they do, you've found your culprit for the price of a new RJ45 crimp.