Trends data repeatedly cycling up-and-down on a 14-minute interval

Been scratching my head over something similar on my shepherd's hut setup and wanted to see if anyone else has experienced this.

Running a Victron SmartSolar MPPT 100|20 with a pair of 175W panels, a 200Ah AGM, and a SmartShunt all talking over VE.Smart networking. Last week I started noticing the Trends view in the VictronConnect app showing this odd rhythmic cycling — battery voltage and charge current both stepping up and down in what looked like a remarkably consistent interval. Not random noise, almost metronomic.

My first suspicion was the Battery Protect cutting in and out under a marginal load condition — perhaps something on the hut drawing just enough to trip the low-voltage disconnect repeatedly. Disconnected the BP temporarily and the pattern persisted, so that ruled it out fairly quickly.

Second thought was the MPPT toggling between absorption and float because the battery was sitting right on the absorption voltage threshold — late afternoon sun in the UK being what it is, inconsistent and fading. That sort of fits, but the regularity of it feels too clean to be purely weather-driven.

A few things I'm genuinely curious about:

• Has anyone seen this behaviour linked to VE.Smart networking sync intervals rather than actual electrical behaviour?
• Could a dodgy cell in an AGM cause the BMS-equivalent (internal resistance shift) to produce this kind of oscillation?
• Is the Trends graph itself possibly smoothing or resampling data in a way that creates artificial periodicity?

Worth noting my panels are on a south-facing fixed mount, so no partial shading issues, and cable runs are reasonably short with decent terminations throughout.

Anyone had something similar? Keen to compare notes before I start

@WattEd — classic symptom of the MPPT algorithm hunting due to partial shading or a mismatch between your panel configuration and the controller's voltage window.

With two 175W panels, are they wired series or parallel? Series on a 100|20 can push Voc uncomfortably high in cold morning conditions, causing the controller to back off and retry — hence that rhythmic cycling.

Worth checking in VictronConnect under the History tab: look for repeated absorption entries resetting. If the cycle is precisely 14 minutes, that's almost certainly the absorption timer resetting rather than a genuine MPPT hunt.

On my shepherd's hut I had something identical until I corrected a loose MC4 connector causing intermittent open-circuit voltage spikes. The controller was seeing phantom disconnects. Worth checking all terminations first before chasing software settings.

@WattEd the 14-minute cycling is almost certainly your MPPT sweeping the full IV curve periodically — the 100|20 does this by default to re-discover the global MPP. If you've got any partial shading hitting those panels at certain times of day, it'll keep triggering a full rescan because the algorithm can't settle on a stable peak.

Worth checking:

• Panel wiring — series vs parallel matters enormously with partial shade
• VRM portal trends — look at whether voltage dips coincide with the cycling
• Firmware — make sure you're on the latest SmartSolar firmware via VictronConnect

On my narrowboat I had identical behaviour until I realised a mooring post was casting shadow across one panel for about two hours mid-afternoon. Sorted the shading and the hunting stopped completely. Physical cause first, software second.

@LH_Marine and @BordersExplorer have both touched on plausible causes, but I'd want to rule out something more mundane first: battery voltage thresholds triggering absorption/float cycling.

On my static caravan setup I had near-identical periodic dips — turned out my absorption time was set far too short, so the controller kept bouncing between charge states on a suspiciously regular interval. Nothing exotic, just misconfigured parameters in VictronConnect.

Worth checking your charge algorithm settings before assuming it's MPPT hunting or shading issues. Pull the history tab in VictronConnect and look at whether those cycles correspond with state-of-charge transitions. If you're seeing voltage stepping down at each trough rather than oscillating symmetrically, that's your culprit right there.

What battery chemistry are you running? LiFePO4 with a BMS cutting in/out would also produce this pattern, and that's a completely different problem to solve.

@FormerTeacher what's the mundane thing you're ruling out then — loose MC4? Because yeah that'll do it, had exactly that on my static. Looked like hunting, was just a dodgy connection oxidising in the damp.

Also worth checking — are both panels actually wired in series or parallel? Sounds obvious but I've seen people mix it up and the 100|20 will throw a wobbler if the Voc is wrong for the config.

Grab the VictronConnect app and look at the raw history graph. If it's perfectly regular at 14 mins it's likely the sweep cycle. If it's messy intervals, something physical is off.